2018 Vol. 43, No. 5
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2018, 43(5): 1367-1383.
doi: 10.3799/dqkx.2018.400
Abstract:
Nanogeoscience is a highly comprehensive and overlapping subject, with combination of nanotechnology and geoscience. It is hard to partition nanogeoscience into single discipline of the classical sense. Its research objects mainly include nanomaterials and nanopores, which are widely distributed on the earth and have diverse causes and obvious scale effects. To nanomaterials, researchers use various image analysis methods to observe their shape, size and aggregation model, also investigate the crystal structure and molecular structure through all kinds of spectroscopy methods. To nanopores, researchers use image analysis, fluid invasion combined with numerical simulation methods, to characterize pore morphology, pore size distribution, connectivity and other characteristics. On the basis and framework of traditional geoscience research, the systematic research of nanogeoscience as a discipline is to solve the scientific problems about nanomaterials and nanopores in each sphere of the earth, such as formation, migration, aggregation and existence form of nanomaterials, as well as formation and evolution of nanopores. Consequently, it deepens the cognition of nanoscale characteristics of branches like mineralogy, petrology, structural geology, geochemistry as well as resources, disasters and environment. The emergence and development of nanogeoscience have brought human beings into a new level in understanding and transforming nature. It is the inevitable way for the development of the earth and planetary sciences. Related research has provided new theoretical basis for mineral deposit exploration, resource development, new energy utilization, prevention and treatment of environmental pollution and geological disaster, etc. It has immeasurable scientific significance and application values.
Nanogeoscience is a highly comprehensive and overlapping subject, with combination of nanotechnology and geoscience. It is hard to partition nanogeoscience into single discipline of the classical sense. Its research objects mainly include nanomaterials and nanopores, which are widely distributed on the earth and have diverse causes and obvious scale effects. To nanomaterials, researchers use various image analysis methods to observe their shape, size and aggregation model, also investigate the crystal structure and molecular structure through all kinds of spectroscopy methods. To nanopores, researchers use image analysis, fluid invasion combined with numerical simulation methods, to characterize pore morphology, pore size distribution, connectivity and other characteristics. On the basis and framework of traditional geoscience research, the systematic research of nanogeoscience as a discipline is to solve the scientific problems about nanomaterials and nanopores in each sphere of the earth, such as formation, migration, aggregation and existence form of nanomaterials, as well as formation and evolution of nanopores. Consequently, it deepens the cognition of nanoscale characteristics of branches like mineralogy, petrology, structural geology, geochemistry as well as resources, disasters and environment. The emergence and development of nanogeoscience have brought human beings into a new level in understanding and transforming nature. It is the inevitable way for the development of the earth and planetary sciences. Related research has provided new theoretical basis for mineral deposit exploration, resource development, new energy utilization, prevention and treatment of environmental pollution and geological disaster, etc. It has immeasurable scientific significance and application values.
2018, 43(5): 1384-1407.
doi: 10.3799/dqkx.2018.533
Abstract:
Research on naturally occurring nanosized minerals is a central domain of Nanogeoscience. However, the use of the concept "Nanominerals" is acutally not as strict as it is supposed, i.e., sometimes the use of the concept is inconsistent with the classical definition of "Nanominerals". In this paper, the concept "Nanostructured Minerals" is proposed to replace the concept "Nanominerals", and a brief description on the suggested concept, as well as a related discussion, is given. A definition of the term nanostructured minerals is proposed and discussed. Exemplified by the tubular nanostructured minerals (halloysite and imogolite), the globular nanostructured mineral (allophane) and the porous nanostructured mineral (diatomaceous opal-A), the unique structure and surface-interface reactivity of nanostructured minerals are comprehensively discussed. The role of the above-mentioned uniqueness in the applications of the nanostructured minerals is summarized. In addition, the functions of the interlayer nanostructure exhibited by some nanostructured minerals such as montmorillonite on the earth matter circle (hydrocarbon generation and shale gas storage) are discussed.
Research on naturally occurring nanosized minerals is a central domain of Nanogeoscience. However, the use of the concept "Nanominerals" is acutally not as strict as it is supposed, i.e., sometimes the use of the concept is inconsistent with the classical definition of "Nanominerals". In this paper, the concept "Nanostructured Minerals" is proposed to replace the concept "Nanominerals", and a brief description on the suggested concept, as well as a related discussion, is given. A definition of the term nanostructured minerals is proposed and discussed. Exemplified by the tubular nanostructured minerals (halloysite and imogolite), the globular nanostructured mineral (allophane) and the porous nanostructured mineral (diatomaceous opal-A), the unique structure and surface-interface reactivity of nanostructured minerals are comprehensively discussed. The role of the above-mentioned uniqueness in the applications of the nanostructured minerals is summarized. In addition, the functions of the interlayer nanostructure exhibited by some nanostructured minerals such as montmorillonite on the earth matter circle (hydrocarbon generation and shale gas storage) are discussed.
2018, 43(5): 1408-1424.
doi: 10.3799/dqkx.2018.401
Abstract:
Nanomineral-aqueous solution interface is ubiquitous in the earth environment, and is of critical importance to many fundamental geochemical processes. The study on nanomineral-aqueons interfaces is therefore at the forefront of nanogeochemistry. In this paper, it briefly introduces the basic concepts and recent research progresses in the field of nanomineral-aqueons interfaces, and specifically illustrates major interfacial processes including aggregation, adsorption, dissolution and chemical reaction of nanominerals. The effects and microscopic mechanisms of nanomineral characteristics (such as composition, structure, size, morphology, surface protection layer, etc.) and environmental media conditions (including pH, ionic strength, chemical reaction substances, NOM concentration and composition, microorganism, light radiation, etc.) on the interfacial processes are discussed in detail. In view of the opportunities and challenges presented in this field, some suggestions for future research directions are put forward.
Nanomineral-aqueous solution interface is ubiquitous in the earth environment, and is of critical importance to many fundamental geochemical processes. The study on nanomineral-aqueons interfaces is therefore at the forefront of nanogeochemistry. In this paper, it briefly introduces the basic concepts and recent research progresses in the field of nanomineral-aqueons interfaces, and specifically illustrates major interfacial processes including aggregation, adsorption, dissolution and chemical reaction of nanominerals. The effects and microscopic mechanisms of nanomineral characteristics (such as composition, structure, size, morphology, surface protection layer, etc.) and environmental media conditions (including pH, ionic strength, chemical reaction substances, NOM concentration and composition, microorganism, light radiation, etc.) on the interfacial processes are discussed in detail. In view of the opportunities and challenges presented in this field, some suggestions for future research directions are put forward.
2018, 43(5): 1425-1438.
doi: 10.3799/dqkx.2018.402
Abstract:
The rise and development of nanogeology lead to exploration of the solid earth materials at the nanoscale, exerting extensive and profound impact on various fields of earth science. As an important branch of nanogeology, nanomineralogy also explores the structure and properties of the minerals including biominerals at the nanoscale, eliminating the limitations of traditional mineralogy which only regards the mineral as ideal crystal lattice, of which mesocrystal is one breakthrough. Mesocrystals represent a class of crystalline nanostructured materials drawing increasing attention from physicists and chemists especially material chemists in recent years. Mesocrystals are the products of non-classical crystallization process with nanoparticles as the basic subunits, sharing the properties of nanoparticles with order on the macroscopic length scale. It has been found that a number of biominerals including vertebrate bones and teeth, nacre, egg shells, sea urchin spines, foraminifera, and corals have the mesocrystals structure. Therefore, re-understanding the biomineralization at the nanoscale and the perspective of mesocrystals will undoubtedly help to reveal the formation mechanisms of hierarchical nanostructures in biominerals and expand the scientific connotation of nanomineralogy. Firstly, the basic concepts of biomineralization and biominerals are introduced. Then, the concept and structural feature of mesocrystals are expounded. Finally, the mesocrystal structure in biominerals and the mechanisms of mesocrystal formation are clarified in detail, referring to several physical and chemical processes such as alignment by the organic matrix, alignment by physical forces, connection by mineral bridges or organic bridges, alignment by spatial constraints, alignment by oriented attachment and alignment by face selective molecules. It is expected that this study may promote the further development of nanomineralogy.
The rise and development of nanogeology lead to exploration of the solid earth materials at the nanoscale, exerting extensive and profound impact on various fields of earth science. As an important branch of nanogeology, nanomineralogy also explores the structure and properties of the minerals including biominerals at the nanoscale, eliminating the limitations of traditional mineralogy which only regards the mineral as ideal crystal lattice, of which mesocrystal is one breakthrough. Mesocrystals represent a class of crystalline nanostructured materials drawing increasing attention from physicists and chemists especially material chemists in recent years. Mesocrystals are the products of non-classical crystallization process with nanoparticles as the basic subunits, sharing the properties of nanoparticles with order on the macroscopic length scale. It has been found that a number of biominerals including vertebrate bones and teeth, nacre, egg shells, sea urchin spines, foraminifera, and corals have the mesocrystals structure. Therefore, re-understanding the biomineralization at the nanoscale and the perspective of mesocrystals will undoubtedly help to reveal the formation mechanisms of hierarchical nanostructures in biominerals and expand the scientific connotation of nanomineralogy. Firstly, the basic concepts of biomineralization and biominerals are introduced. Then, the concept and structural feature of mesocrystals are expounded. Finally, the mesocrystal structure in biominerals and the mechanisms of mesocrystal formation are clarified in detail, referring to several physical and chemical processes such as alignment by the organic matrix, alignment by physical forces, connection by mineral bridges or organic bridges, alignment by spatial constraints, alignment by oriented attachment and alignment by face selective molecules. It is expected that this study may promote the further development of nanomineralogy.
2018, 43(5): 1439-1449.
doi: 10.3799/dqkx.2018.403
Abstract:
To promote the understanding, further research, and exploration and application of nano-minerals and nan-mineral resources, the narrow and broad conception of mineral nano-particle and nano-mineral as well as the types of nano-minerals and their morphological types are elaborated in this paper. Then, the nature of the formation and stability of nano-minerals in terms of crystal structure and crystal chemistry are discussed. It is found that formation of nano-minerals and mineral nano-particles are controlled by intrinsic factors and extrinsic factors. In addition, this paper presents the research field of nano-mineralogy and its importance in the research of critical zone. Finally, it proposes the conception and properties of nano-mineral resources and its potential applications.
To promote the understanding, further research, and exploration and application of nano-minerals and nan-mineral resources, the narrow and broad conception of mineral nano-particle and nano-mineral as well as the types of nano-minerals and their morphological types are elaborated in this paper. Then, the nature of the formation and stability of nano-minerals in terms of crystal structure and crystal chemistry are discussed. It is found that formation of nano-minerals and mineral nano-particles are controlled by intrinsic factors and extrinsic factors. In addition, this paper presents the research field of nano-mineralogy and its importance in the research of critical zone. Finally, it proposes the conception and properties of nano-mineral resources and its potential applications.
2018, 43(5): 1450-1463.
doi: 10.3799/dqkx.2018.404
Abstract:
Nanominerals are the bridge to link atoms/molecules to bulk materials and therefore important for investigating microscopic mechanisms of macroscopic phenomena involving minerals. With rapid development of nanogeosciences, more and more studies have been made on the origin, distribution, and reactivity of nanominerals in natural environment. In this paper, the origin, size-dependent properties, aggregation behavior, biotic and abiotic interfacial reactions of common naturally occurring nanominerals, as well as their impacts on biogeochemical cycles of elements, are summarized. Specifically, the special adsorption capacity, dissolution rate, aggregation state, catalytic activity, and redox reactivity of environmental related nanominerals are discussed in detail. It is of particular importance to study the different properties and relativities between nanominerals and their bulk counterparts for completely understanding the roles of minerals in various geological processes, which can promote the studies in geosciences at molecular scale.
Nanominerals are the bridge to link atoms/molecules to bulk materials and therefore important for investigating microscopic mechanisms of macroscopic phenomena involving minerals. With rapid development of nanogeosciences, more and more studies have been made on the origin, distribution, and reactivity of nanominerals in natural environment. In this paper, the origin, size-dependent properties, aggregation behavior, biotic and abiotic interfacial reactions of common naturally occurring nanominerals, as well as their impacts on biogeochemical cycles of elements, are summarized. Specifically, the special adsorption capacity, dissolution rate, aggregation state, catalytic activity, and redox reactivity of environmental related nanominerals are discussed in detail. It is of particular importance to study the different properties and relativities between nanominerals and their bulk counterparts for completely understanding the roles of minerals in various geological processes, which can promote the studies in geosciences at molecular scale.
2018, 43(5): 1464-1473.
doi: 10.3799/dqkx.2018.405
Abstract:
Cinopyroxene and spinel (magnetite) occur as oriented intergrowths within olivine of the dunite in the Bulqiza ophiolite, Albania. The size of the inclusion minerals is 1-10 μm, and some of them are nanoscale in 200-500 nm. The fresh dunite has a mineral assemblage of olivine, spinel and cinopyroxene. The Fo content of its olivine is 94.7-96.0, and the Cr# of spinel is about 76.5-82.4, higher than that in the spinel in common dunite from ophiolite mantle (Cr#>60). Thus it is proposed that previously depleted mantle harzburgite reacted with the melt containing Ti, Cr, Fe, and produced an olivine solid solution added with Ti4+, Al3+, Ca2+, Fe3+, and some of Cr3+ entered interstitial chromite. Due to the fast cooling rate of the rock or rapid tectonic emplacement, the exsolution textures in olivine and compositional zones of chromite are preserved. Based on the mineral compositions of chromian spinel-olivine, it is found that the relatively low partial melting degree of the harzburgite is 30%-40%, and the degree of partial melting of dunite is about 40%, indicating a significant difference of tectonic setting. It is suggested that the Bulqiza ophiolite had multi-stage evolution processes.When oceanic crustal slabs were trapped in mid ocean ridge, they were modified by tholeiitic magmas or partial melting, which occurred interaction or metasomatism, then later reaction with boninitic magma in suprasubduction zones (SSZ) generated more Mg, Si and Cr melt, resulting in high degree of partial melting for the mantle peridotite and dunite.
Cinopyroxene and spinel (magnetite) occur as oriented intergrowths within olivine of the dunite in the Bulqiza ophiolite, Albania. The size of the inclusion minerals is 1-10 μm, and some of them are nanoscale in 200-500 nm. The fresh dunite has a mineral assemblage of olivine, spinel and cinopyroxene. The Fo content of its olivine is 94.7-96.0, and the Cr# of spinel is about 76.5-82.4, higher than that in the spinel in common dunite from ophiolite mantle (Cr#>60). Thus it is proposed that previously depleted mantle harzburgite reacted with the melt containing Ti, Cr, Fe, and produced an olivine solid solution added with Ti4+, Al3+, Ca2+, Fe3+, and some of Cr3+ entered interstitial chromite. Due to the fast cooling rate of the rock or rapid tectonic emplacement, the exsolution textures in olivine and compositional zones of chromite are preserved. Based on the mineral compositions of chromian spinel-olivine, it is found that the relatively low partial melting degree of the harzburgite is 30%-40%, and the degree of partial melting of dunite is about 40%, indicating a significant difference of tectonic setting. It is suggested that the Bulqiza ophiolite had multi-stage evolution processes.When oceanic crustal slabs were trapped in mid ocean ridge, they were modified by tholeiitic magmas or partial melting, which occurred interaction or metasomatism, then later reaction with boninitic magma in suprasubduction zones (SSZ) generated more Mg, Si and Cr melt, resulting in high degree of partial melting for the mantle peridotite and dunite.
2018, 43(5): 1474-1480.
doi: 10.3799/dqkx.2018.406
Abstract:
The study of the distribution of structural water at microscopic scale can provide important evidences for the formation environment and tectonic evolution dynamics of UHP metamorphic rocks.In order to investigate the distribution characteristics and the relationship between occurrence state and microstructure defects of "nominal anhydrous minerals" (NAMs) structure water in ultrahigh pressure metamorphic rocks from Dabie Mountains, the NAMs such as coesite in eclogites of the Shima area from Dabie Mountains were studied by FTIR analysis and first-principle calculations. FTIR studies show that the main absorption peaks of coesite are (Ⅰ) 3 561-3 580 cm-1, (Ⅱ) 3 433-3 462 cm-1 and (Ⅲ) 3 412-3 425 cm-1 respectively. The structural water content of the coesites in Shima is 15×10-6-52×10-6, with an average of 32×10-6. The vacancy formation energies of the (4H)Si and (AlH)Si complex defect coesite supercells (2×1×1) calculated by the first principle are -4.92 eV and -3.10 eV respectively. The Raman peaks at 3 526 and 3 198 cm-1 in the hydrogen-containing defect models of coesite are consistent with the experimental results. The vacancy defect formation energy of the (4H)Si complex defect model is lower, which is the more stable structure than (AlH)Si. Moreover, the (OH)4\begin{document}$ \Leftrightarrow $\end{document}
The study of the distribution of structural water at microscopic scale can provide important evidences for the formation environment and tectonic evolution dynamics of UHP metamorphic rocks.In order to investigate the distribution characteristics and the relationship between occurrence state and microstructure defects of "nominal anhydrous minerals" (NAMs) structure water in ultrahigh pressure metamorphic rocks from Dabie Mountains, the NAMs such as coesite in eclogites of the Shima area from Dabie Mountains were studied by FTIR analysis and first-principle calculations. FTIR studies show that the main absorption peaks of coesite are (Ⅰ) 3 561-3 580 cm-1, (Ⅱ) 3 433-3 462 cm-1 and (Ⅲ) 3 412-3 425 cm-1 respectively. The structural water content of the coesites in Shima is 15×10-6-52×10-6, with an average of 32×10-6. The vacancy formation energies of the (4H)Si and (AlH)Si complex defect coesite supercells (2×1×1) calculated by the first principle are -4.92 eV and -3.10 eV respectively. The Raman peaks at 3 526 and 3 198 cm-1 in the hydrogen-containing defect models of coesite are consistent with the experimental results. The vacancy defect formation energy of the (4H)Si complex defect model is lower, which is the more stable structure than (AlH)Si. Moreover, the (OH)4
2018, 43(5): 1481-1488.
doi: 10.3799/dqkx.2018.407
Abstract:
In order to reveal the structure changes of microcrystalline graphite in the process of oxidation and expansion, the products were characterized by means of SEM-EDS, XRD, Raman and FTIR in this study. The results show that the interlayer distance of microcrystalline graphite oxide is enlarged and many functional groups including hydroxyl, carboxyl and epoxy groups are bonded on the graphene layer in the oxidation process. In addition, with the increase of oxidant (KMnO4), the space distance, structural defects and disorder of oxidized product increased gradually. After being expanded with high temperature, some of the oxygen-containing functional groups in the structure were removed, and the oxidized microcrystalline graphite was reduced partly. In addition, the structural defects and disorder degrees of expanded microcrystalline graphite reduced, and local sp2 regions were recovered. The expanded microcrystalline graphite particles contained abundant network pore structures with pore sizes of 2-5 nm.
In order to reveal the structure changes of microcrystalline graphite in the process of oxidation and expansion, the products were characterized by means of SEM-EDS, XRD, Raman and FTIR in this study. The results show that the interlayer distance of microcrystalline graphite oxide is enlarged and many functional groups including hydroxyl, carboxyl and epoxy groups are bonded on the graphene layer in the oxidation process. In addition, with the increase of oxidant (KMnO4), the space distance, structural defects and disorder of oxidized product increased gradually. After being expanded with high temperature, some of the oxygen-containing functional groups in the structure were removed, and the oxidized microcrystalline graphite was reduced partly. In addition, the structural defects and disorder degrees of expanded microcrystalline graphite reduced, and local sp2 regions were recovered. The expanded microcrystalline graphite particles contained abundant network pore structures with pore sizes of 2-5 nm.
2018, 43(5): 1489-1502.
doi: 10.3799/dqkx.2018.408
Abstract:
With at least one dimension less than 100 nm, nanoparticles have been naturally synthesized through biogeochemistry processes in the earth system for billions of years.These nanoparticles have unique properties, and they can participate and thus play distinguished role in various geochemistry processes. From the geochemistry perspective, this paper elaborates the definition and classification of nanoparticles occurring in the environment, emphasizing naturally occurring nanoparticles and incidental nanoparticles in aquatic and weathering crust system, on basis of which nano-minerals are further distinguished from mineral nanoparticles. In addition, origin and formation of nanoparticles in atmosphere and related environmental impact are discussed. In this paper, it also presents current techniques and methods for the characterization and identification of environmental nanoparticles. Furthermore, the geochemistry functions of nanoparticles and their environmental implications are discussed and elucidated, and the frontier issues in this field are summarized.
With at least one dimension less than 100 nm, nanoparticles have been naturally synthesized through biogeochemistry processes in the earth system for billions of years.These nanoparticles have unique properties, and they can participate and thus play distinguished role in various geochemistry processes. From the geochemistry perspective, this paper elaborates the definition and classification of nanoparticles occurring in the environment, emphasizing naturally occurring nanoparticles and incidental nanoparticles in aquatic and weathering crust system, on basis of which nano-minerals are further distinguished from mineral nanoparticles. In addition, origin and formation of nanoparticles in atmosphere and related environmental impact are discussed. In this paper, it also presents current techniques and methods for the characterization and identification of environmental nanoparticles. Furthermore, the geochemistry functions of nanoparticles and their environmental implications are discussed and elucidated, and the frontier issues in this field are summarized.
2018, 43(5): 1503-1517.
doi: 10.3799/dqkx.2018.409
Abstract:
Nanogeochemistry can help humans to understand and explore the geological and geochemical processes on the earth from microcosmic point of view, which have a significant impact on the research and application in the resources and environmental issues. Nanogeochemistry has made important progress in the field of mineral exploration. Based on the summarization of previous academic achievements and combined with this study. In this paper, it presents metallic nanoparticels from the formation process, migration patterns, occurrences in supergenic medium, and capture approaches and further states the theory of nanogeochemistry for mineral exploration and its application significance. The migration mechanism of nanoparticles can be summarized as follows:nanoparticles of ore-forming elements or minerals formed in the metallogenic process, released from the orebody of deposits by weathering, formed active metallic nanoparticles, can be adsorbed onto surface of gas molecular because of their tremendous surface energies and then be migrated to the earth surface through covers by their ascending geogas carrier or their gas-like phases, with part of them remained in geogases and other parts trapped into soil geochemical barriers and creature. The migration mechanism has been proven by lots of in-situ observation cases of metallic nanoparticles occurred in supergenic medium. Some successful cases show that separation of nanoparticles of mobile metals could be effectively applied to prospect concealed ore deposits under covers.
Nanogeochemistry can help humans to understand and explore the geological and geochemical processes on the earth from microcosmic point of view, which have a significant impact on the research and application in the resources and environmental issues. Nanogeochemistry has made important progress in the field of mineral exploration. Based on the summarization of previous academic achievements and combined with this study. In this paper, it presents metallic nanoparticels from the formation process, migration patterns, occurrences in supergenic medium, and capture approaches and further states the theory of nanogeochemistry for mineral exploration and its application significance. The migration mechanism of nanoparticles can be summarized as follows:nanoparticles of ore-forming elements or minerals formed in the metallogenic process, released from the orebody of deposits by weathering, formed active metallic nanoparticles, can be adsorbed onto surface of gas molecular because of their tremendous surface energies and then be migrated to the earth surface through covers by their ascending geogas carrier or their gas-like phases, with part of them remained in geogases and other parts trapped into soil geochemical barriers and creature. The migration mechanism has been proven by lots of in-situ observation cases of metallic nanoparticles occurred in supergenic medium. Some successful cases show that separation of nanoparticles of mobile metals could be effectively applied to prospect concealed ore deposits under covers.
2018, 43(5): 1518-1523.
doi: 10.3799/dqkx.2018.410
Abstract:
Generally speaking, a rock is broken by shearing action or tensile force, in that case, why can we find some fracture structures perpendicular to the pressure direction? It can be solved through H Odé shear deformation theory. In plastic (or viscous-elastic) deformation, there is a velocity discontinuity which may be gained from a yield condition due to a medium differentiation, and thus the medium can just shear slip along the characteristic planes with an equal velocity. This theory is also called the plastic shearing criteria, and it was firstly verified from a macroscopic-mesoscopic mechanics representation, including the fracture planes in compressive zone, extreme point rupture of Griffith crack under normal press, and cataclastic flow in vertical pressure. Furthermore, high temperature and high pressure (HT/HP) experiment to granite samples was carried out, and the thin shells of crack surfaces, which are perpendicular to the axle load, were taken for the SEM determination. Then the micro/nanosized phenomena observed in crack surfaces with H Odé mechanics representation are compared with the textures of general shearing yield function from three aspects. (1) Viscous-elastic deformation:the experimental specimens passed HT/HP are more likely to produce a plastic compactive volumetric flow, invloving not only viscous deformation but also elastic one. Consequently, the specimens can exhibit effects of nano-coating and nano-layering. (2) Nanosized texture:nanosized grain (with diameter 60-80 nm) can turn into single nanoparticle-nanoline-nanolayer texture, and aggregate grains may be subdivided into granular, linear granular and schistose granular textures, etc. (3) Ordered fabrication:though preferred orientations of the granular flow and streak flow in H Odé shear fractures belong to a weaker scale than common shearing, their yield characteristics are entirely corresponding with the latter from comprehensive analysis. It is suggested that H Odé shear theory can be applied to research some few unconventional deformation phenomena, and it can offer a new perspective for nanogeology researches.
Generally speaking, a rock is broken by shearing action or tensile force, in that case, why can we find some fracture structures perpendicular to the pressure direction? It can be solved through H Odé shear deformation theory. In plastic (or viscous-elastic) deformation, there is a velocity discontinuity which may be gained from a yield condition due to a medium differentiation, and thus the medium can just shear slip along the characteristic planes with an equal velocity. This theory is also called the plastic shearing criteria, and it was firstly verified from a macroscopic-mesoscopic mechanics representation, including the fracture planes in compressive zone, extreme point rupture of Griffith crack under normal press, and cataclastic flow in vertical pressure. Furthermore, high temperature and high pressure (HT/HP) experiment to granite samples was carried out, and the thin shells of crack surfaces, which are perpendicular to the axle load, were taken for the SEM determination. Then the micro/nanosized phenomena observed in crack surfaces with H Odé mechanics representation are compared with the textures of general shearing yield function from three aspects. (1) Viscous-elastic deformation:the experimental specimens passed HT/HP are more likely to produce a plastic compactive volumetric flow, invloving not only viscous deformation but also elastic one. Consequently, the specimens can exhibit effects of nano-coating and nano-layering. (2) Nanosized texture:nanosized grain (with diameter 60-80 nm) can turn into single nanoparticle-nanoline-nanolayer texture, and aggregate grains may be subdivided into granular, linear granular and schistose granular textures, etc. (3) Ordered fabrication:though preferred orientations of the granular flow and streak flow in H Odé shear fractures belong to a weaker scale than common shearing, their yield characteristics are entirely corresponding with the latter from comprehensive analysis. It is suggested that H Odé shear theory can be applied to research some few unconventional deformation phenomena, and it can offer a new perspective for nanogeology researches.
2018, 43(5): 1524-1531.
doi: 10.3799/dqkx.2018.411
Abstract:
Nanoparticles are widely found in the ductile shear zone, and their development characteristics are closely related to the fault shear deformation. To better understand the morphological characteristics of nanoparticles in the ductile shear zone of Red River Fault, the formation law and the relationship with Red River fault activity, we have traversed the ductile shear zone of Red River Fault three times in different sections, collecting almost 100 samples including mylonite, gneiss and schist. One type of nano monomers was found by the scanning electron microscopy (SEM), which show unique morphology features, including spherulitic monomer. These monomers are scattered over the mineral surface. At the same time, twelve kinds of nanoparticles aggregations were found, with different aggregations showing obvious differences in their morphology features and development stages, reflecting different tectonic stress, temperature and pressure conditions that different areas have experienced in the shear process of the ductile shear zone of Red River Fault.
Nanoparticles are widely found in the ductile shear zone, and their development characteristics are closely related to the fault shear deformation. To better understand the morphological characteristics of nanoparticles in the ductile shear zone of Red River Fault, the formation law and the relationship with Red River fault activity, we have traversed the ductile shear zone of Red River Fault three times in different sections, collecting almost 100 samples including mylonite, gneiss and schist. One type of nano monomers was found by the scanning electron microscopy (SEM), which show unique morphology features, including spherulitic monomer. These monomers are scattered over the mineral surface. At the same time, twelve kinds of nanoparticles aggregations were found, with different aggregations showing obvious differences in their morphology features and development stages, reflecting different tectonic stress, temperature and pressure conditions that different areas have experienced in the shear process of the ductile shear zone of Red River Fault.
2018, 43(5): 1532-1541.
doi: 10.3799/dqkx.2017.540
Abstract:
In order to investigate the development process and formation mechanism of nanoparticles in ductile shear zone, three types of rocks were sampled from the Xiaomei ductile shear zone on Hainan island, including granite, granitic gneiss and quartz schist. And the morphology of the nanoparticles was observed by scanning electron microscope (SEM). The results show that there are two kinds of basic forms of nanoparticles:spherical and columnar, and the nanoparticles (nanograins) are widely developed in all three kinds of rocks. The nanoparticles (nanorods) in granite gneiss are most developed. The aggregated morphology of nanoparticles indicates that the development can be divided into three stages including granulation, alienation and stratification accumulation. The second phase of activity starts with the activation stage which forms complex-nanoparticles, and then repeats the above stage. Combined with the morphological changes of nanoparticles, it is concluded that the formation mechanism is probably brittle-ductile deformation.
In order to investigate the development process and formation mechanism of nanoparticles in ductile shear zone, three types of rocks were sampled from the Xiaomei ductile shear zone on Hainan island, including granite, granitic gneiss and quartz schist. And the morphology of the nanoparticles was observed by scanning electron microscope (SEM). The results show that there are two kinds of basic forms of nanoparticles:spherical and columnar, and the nanoparticles (nanograins) are widely developed in all three kinds of rocks. The nanoparticles (nanorods) in granite gneiss are most developed. The aggregated morphology of nanoparticles indicates that the development can be divided into three stages including granulation, alienation and stratification accumulation. The second phase of activity starts with the activation stage which forms complex-nanoparticles, and then repeats the above stage. Combined with the morphological changes of nanoparticles, it is concluded that the formation mechanism is probably brittle-ductile deformation.
2018, 43(5): 1542-1548.
doi: 10.3799/dqkx.2018.412
Abstract:
Natural gas hydrate is a kind of clean energy with potential huge reserves. Hydrate researches gradually extend to nano-and micro-scale recently. Nano science has been a part of hydrate researches, including occurrence, gas production and hydrate based technologies of downstream such as gas storage and separation. The common key is heat and mass transfer of hydrate formation and dissociation on the surface, inside and between nanomaterials. From 9th international conference on gas hydrates (ICGH9) as point of penetration in this paper, it reviews nano-scale studies on occurrence and gas production of marine gas hydrates, as well as downstream utilizations of gas hydrate technology.The results show that study of heat and mass transfer inside nanomaterial during hydrate formation and dissociation is needed to be developed. There is a blank area that accumulative effect of micro-nanomaterial during hydrate formation and dissociation. These questions have become bottleneck of gas hydrate occurrence and production. In the future, researches should focus on heat and mass transfer inside nanomaterial during hydrate formation and dissociation and use this as a link to systematively study occurrence and production of natural gas hydrates.
Natural gas hydrate is a kind of clean energy with potential huge reserves. Hydrate researches gradually extend to nano-and micro-scale recently. Nano science has been a part of hydrate researches, including occurrence, gas production and hydrate based technologies of downstream such as gas storage and separation. The common key is heat and mass transfer of hydrate formation and dissociation on the surface, inside and between nanomaterials. From 9th international conference on gas hydrates (ICGH9) as point of penetration in this paper, it reviews nano-scale studies on occurrence and gas production of marine gas hydrates, as well as downstream utilizations of gas hydrate technology.The results show that study of heat and mass transfer inside nanomaterial during hydrate formation and dissociation is needed to be developed. There is a blank area that accumulative effect of micro-nanomaterial during hydrate formation and dissociation. These questions have become bottleneck of gas hydrate occurrence and production. In the future, researches should focus on heat and mass transfer inside nanomaterial during hydrate formation and dissociation and use this as a link to systematively study occurrence and production of natural gas hydrates.
2018, 43(5): 1549-1561.
doi: 10.3799/dqkx.2018.413
Abstract:
The Kueishantao shallow-water hydrothermal system, offshore northeast Taiwan, discharges large amounts of native sulfur. In order to unveil the distribution of trace elements in the native sulfur, we analyzed the elemental contents of sulfur matrix and microscopic inclusions in the KST native sulfur by laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS). The results indicate that the sulfur matrix only contains volatile chalcophile elements such as As, Se, and Te, which are mainly originated from magma degassing. The siderophile elements including Fe, Mn, Co, and Ni are mainly contributed by the andesite host rock of the KST system. These elements are enriched in the Fe-rich and/or Si-bearing inclusions as various sulfides. Al, Zn, Ba, Pb, La, Ce, Au, and Ag were significantly enriched in Si-bearing inclusions, suggesting that the occurrence of these elements was mainly controlled by silicate particles.The Cu-rich inclusions contain higher per unit chalcophile elements (Hg, Pb, and Zn) than Fe-rich inclusions. The distribution of trace elements is analyzed in-situ in the KST native sulfur for the first time. This study will help to better understand the geochemical behaviors of trace elements during hydrothermal processes.
The Kueishantao shallow-water hydrothermal system, offshore northeast Taiwan, discharges large amounts of native sulfur. In order to unveil the distribution of trace elements in the native sulfur, we analyzed the elemental contents of sulfur matrix and microscopic inclusions in the KST native sulfur by laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS). The results indicate that the sulfur matrix only contains volatile chalcophile elements such as As, Se, and Te, which are mainly originated from magma degassing. The siderophile elements including Fe, Mn, Co, and Ni are mainly contributed by the andesite host rock of the KST system. These elements are enriched in the Fe-rich and/or Si-bearing inclusions as various sulfides. Al, Zn, Ba, Pb, La, Ce, Au, and Ag were significantly enriched in Si-bearing inclusions, suggesting that the occurrence of these elements was mainly controlled by silicate particles.The Cu-rich inclusions contain higher per unit chalcophile elements (Hg, Pb, and Zn) than Fe-rich inclusions. The distribution of trace elements is analyzed in-situ in the KST native sulfur for the first time. This study will help to better understand the geochemical behaviors of trace elements during hydrothermal processes.
2018, 43(5): 1562-1573.
doi: 10.3799/dqkx.2018.414
Abstract:
The variety of morphology and compositions of pyrite in the Logatchev hydrothermal area of North Atlantic is particular and representative. In this paper, it analyzes the mineralogical characteristics of pyrite systematically by scanning electron microscopy (SEM) and electron probe microanalysis(EPMA). It is found that the size of granular pyrite is inhomogeneous with high contents of Fe and S and low contents of trace elements. There are three types of pyrite framboids in this area:loosely arranged framboids, spherical framboids and framboids with enhedral crystal structure. The content of Cu in framboids is large, and the different framboid crystals have different chemical compositions. Part of colloidal pyrite develops multilayer girdles, and it is formed by the polymerization of nano-micro pyrite crystals. From the core to the girdles, the contents of S/Fe and Zn show a decreasing trend, while the As content shows an increasing tendency. The analyses show that the earlier granular pyrite is formed directly in a hydrothermal system at higher temperatures, the formation of pyrite is mainly composed of nano and micro pyrite crystals with the attenuation of hydrothermal action. The loosely nano and micro pyrite crystals have a tendency to aggregate framboids. The size and accumulation of framboids vary with the change of the super saturation of solution. The growth of polycrystalline aggregation is from inside girdle to outside girdle, and the difference of aggregation of girdles indicates the alternation of metallogenic environment. Multi-morphologies of pyrite in the area have a complete evolution series from dispersed microcrystals to polycrystalline aggregate to euhedral crystal, which is significant to the understanding of the ways and characteristics of modern seafloor hydrothermal activity and the exploration of the evolution process of the nano crystalline crystal.
The variety of morphology and compositions of pyrite in the Logatchev hydrothermal area of North Atlantic is particular and representative. In this paper, it analyzes the mineralogical characteristics of pyrite systematically by scanning electron microscopy (SEM) and electron probe microanalysis(EPMA). It is found that the size of granular pyrite is inhomogeneous with high contents of Fe and S and low contents of trace elements. There are three types of pyrite framboids in this area:loosely arranged framboids, spherical framboids and framboids with enhedral crystal structure. The content of Cu in framboids is large, and the different framboid crystals have different chemical compositions. Part of colloidal pyrite develops multilayer girdles, and it is formed by the polymerization of nano-micro pyrite crystals. From the core to the girdles, the contents of S/Fe and Zn show a decreasing trend, while the As content shows an increasing tendency. The analyses show that the earlier granular pyrite is formed directly in a hydrothermal system at higher temperatures, the formation of pyrite is mainly composed of nano and micro pyrite crystals with the attenuation of hydrothermal action. The loosely nano and micro pyrite crystals have a tendency to aggregate framboids. The size and accumulation of framboids vary with the change of the super saturation of solution. The growth of polycrystalline aggregation is from inside girdle to outside girdle, and the difference of aggregation of girdles indicates the alternation of metallogenic environment. Multi-morphologies of pyrite in the area have a complete evolution series from dispersed microcrystals to polycrystalline aggregate to euhedral crystal, which is significant to the understanding of the ways and characteristics of modern seafloor hydrothermal activity and the exploration of the evolution process of the nano crystalline crystal.
2018, 43(5): 1574-1586.
doi: 10.3799/dqkx.2017.593
Abstract:
Sandy on conglomerate gas prospecting in Shahezi Formation of Xujiaweizi depression has achieved initial success after several industrial gas flow wells had been drilled in reservoir space of nano-micron size. It is of great importance to determine the relationship between tight reservoir formation and natural gas charge for the exploration plan and "sweet spot" prediction. Based on the analysis of reservoir petrology, reservoir space and diagenetic evolution sequence, principal reasons and formation mechanism of nano-micron pores were determined through calculating the porosity changed by various diagenesis events. It is concluded that the quick subsidence and the huge mechanical compaction in the early diagenetic stage accelerated the damage of primary pores, resulting in the compacting of 'super-tight sandy conglomerates' which are rich in clay and plastic lithic fragments. 'Tight sandy conglomerates' which are rich in rigid components reached the tight grade in the later diagenetic process mainly due to the filling of carbonate cements, thus the formation of later carbonate cements corresponding to the densification threshold, after which the original pores reduced into nano-micron pores greatly. According to analysis of the homogeneous temperature of hydrocarbon inclusion in the calcite cement and burial-thermal history of Shahezi Formation, the compacting of sandy conglomerates happened around 2 500 m in depth and before 100 Ma. According to the comprehensive study of pore evolution history, hydrocarbon generation history and hydrocarbon filling history, gas accumulation occurred both before and after the compacting of sandy conglomerates. Before the compacting of sandy conglomerates, gas generated at a low speed and filled into the reservoir with a weak strength, forming some structural gas pools at the boundary of the depression, and therefore the upward direction of slope where micro amplitude structure developed is the favorable area for prospecting. The peak of gas accumulation occurred after reservoir compacting, characterized by high gas injection strength, forming widely distributed lithologic gas reservoirs, and thus the downdip direction of the slop where distributary channel sandbody developed and closely contact with main source rocks is the potential area for exploration.The comprehensive analysis indicates that the gas pool mainly formed after the reservoir tight with some formed before the reservoir compacting.
Sandy on conglomerate gas prospecting in Shahezi Formation of Xujiaweizi depression has achieved initial success after several industrial gas flow wells had been drilled in reservoir space of nano-micron size. It is of great importance to determine the relationship between tight reservoir formation and natural gas charge for the exploration plan and "sweet spot" prediction. Based on the analysis of reservoir petrology, reservoir space and diagenetic evolution sequence, principal reasons and formation mechanism of nano-micron pores were determined through calculating the porosity changed by various diagenesis events. It is concluded that the quick subsidence and the huge mechanical compaction in the early diagenetic stage accelerated the damage of primary pores, resulting in the compacting of 'super-tight sandy conglomerates' which are rich in clay and plastic lithic fragments. 'Tight sandy conglomerates' which are rich in rigid components reached the tight grade in the later diagenetic process mainly due to the filling of carbonate cements, thus the formation of later carbonate cements corresponding to the densification threshold, after which the original pores reduced into nano-micron pores greatly. According to analysis of the homogeneous temperature of hydrocarbon inclusion in the calcite cement and burial-thermal history of Shahezi Formation, the compacting of sandy conglomerates happened around 2 500 m in depth and before 100 Ma. According to the comprehensive study of pore evolution history, hydrocarbon generation history and hydrocarbon filling history, gas accumulation occurred both before and after the compacting of sandy conglomerates. Before the compacting of sandy conglomerates, gas generated at a low speed and filled into the reservoir with a weak strength, forming some structural gas pools at the boundary of the depression, and therefore the upward direction of slope where micro amplitude structure developed is the favorable area for prospecting. The peak of gas accumulation occurred after reservoir compacting, characterized by high gas injection strength, forming widely distributed lithologic gas reservoirs, and thus the downdip direction of the slop where distributary channel sandbody developed and closely contact with main source rocks is the potential area for exploration.The comprehensive analysis indicates that the gas pool mainly formed after the reservoir tight with some formed before the reservoir compacting.
2018, 43(5): 1587-1593.
doi: 10.3799/dqkx.2017.560
Abstract:
The study of the size and fluidity of tight oil is of great significance for the evaluation and development of tight reservoirs. In order to determine the molecular size and its influence on mobility of tight oil of Lucaogou Formation in Jimusar depression, the average structure parameters of different fractions of Ji 174 tight oil were calculated on the basis of 1H-NMR, IR, elemental analysis and molecular weight measurement. According to the parameters, the molecular structures of several fractions from Ji 174 tight oil were simulated by using the Chemoffice software. The results show that the components of the tight oil are mainly concentrated in the fraction from 350 to 500℃, and there are polycyclic naphthene and polycyclic aromatic structures in the average molecules with the sizes of 1.232-4.026 nm. It is the large molecular scale that leads to high shares of oil molecules in nano-pore-throat and affects the pore throat flow limit of the reservoir.
The study of the size and fluidity of tight oil is of great significance for the evaluation and development of tight reservoirs. In order to determine the molecular size and its influence on mobility of tight oil of Lucaogou Formation in Jimusar depression, the average structure parameters of different fractions of Ji 174 tight oil were calculated on the basis of 1H-NMR, IR, elemental analysis and molecular weight measurement. According to the parameters, the molecular structures of several fractions from Ji 174 tight oil were simulated by using the Chemoffice software. The results show that the components of the tight oil are mainly concentrated in the fraction from 350 to 500℃, and there are polycyclic naphthene and polycyclic aromatic structures in the average molecules with the sizes of 1.232-4.026 nm. It is the large molecular scale that leads to high shares of oil molecules in nano-pore-throat and affects the pore throat flow limit of the reservoir.
2018, 43(5): 1594-1601.
doi: 10.3799/dqkx.2018.415
Abstract:
Nanotechnology plays an important role in the study of microscopic pore structure characterization and hydrocarbon accumulation in unconventional oil and gas tight reservoirs. This paper takes the tight oil reservoir of Permian Lucaogou Formation Jimsar sag in eastern Junggar basin as an example, comprehensively using high pressure mercury analysis, field emission scanning electron microscope (SEM) and nano CT scanning analysis technology to study micronano pore characteristics and structure of Lucaogou Formation tight oil reservoir in Jimsar sag. In addition, the occurrence state of crude in nanopores is analyzed combined with macro and micro characteristics. The results show that nanopore space is one of the main reservoir spaces in the Permian Lucaogou Formation tight oil reservoir in Jimsar sag of Junggar basin. On the whole, the main reservoir pore structure is micron and nano level, showing the characteristics of micron and nano pore throat. Nanopores are generally oil-bearing, and exist mostly in the adsorption state, which changes the traditiongal cognition that micron pore is the only microscopic pore in reservoir. It is the development direction of the future petroleum industry.
Nanotechnology plays an important role in the study of microscopic pore structure characterization and hydrocarbon accumulation in unconventional oil and gas tight reservoirs. This paper takes the tight oil reservoir of Permian Lucaogou Formation Jimsar sag in eastern Junggar basin as an example, comprehensively using high pressure mercury analysis, field emission scanning electron microscope (SEM) and nano CT scanning analysis technology to study micronano pore characteristics and structure of Lucaogou Formation tight oil reservoir in Jimsar sag. In addition, the occurrence state of crude in nanopores is analyzed combined with macro and micro characteristics. The results show that nanopore space is one of the main reservoir spaces in the Permian Lucaogou Formation tight oil reservoir in Jimsar sag of Junggar basin. On the whole, the main reservoir pore structure is micron and nano level, showing the characteristics of micron and nano pore throat. Nanopores are generally oil-bearing, and exist mostly in the adsorption state, which changes the traditiongal cognition that micron pore is the only microscopic pore in reservoir. It is the development direction of the future petroleum industry.
2018, 43(5): 1602-1610.
doi: 10.3799/dqkx.2017.525
Abstract:
Shale pore characteristics are important part of shale reservoir research. Based on the shale samples from Taiyuan Formation and Shanxi Formation in the S-1 well of Qinshui basin, the morphology of the pores was analyzed by argon ion polishing scanning electron microscope (Ar-SEM), and the pores of the Ar-SEM micrographs were quantitatively characterized by pores and cracks analysis system (PCAS). The results show that the pore types of the samples are mainly organic matter pores, intergranular pores, and intragranular pores. The pore sizes are mostly less than 100 nm, accounting for 72.70%-82.13%, and the mesopore ratios are 39.76%-45.48%, which is favorable for pore connectivity and gas migration. The pore structure becomes increasingly more complex with the increase of depth; but the deeper the layer, the more slowly the structural complexity increases with the increase of pore area.There is an inflection point in the vicinity of Ro, max=2 for the pore structure complexity. In the high maturity stage, the complexity of the pore structure gets increasingly lower with the increase of the maturity, and the structure complexity is lower as the pore area is larger; in the over mature stage, pore structure is increasingly more complex with the increase of maturity, and the larger the pore area, the greater the structural complexity.
Shale pore characteristics are important part of shale reservoir research. Based on the shale samples from Taiyuan Formation and Shanxi Formation in the S-1 well of Qinshui basin, the morphology of the pores was analyzed by argon ion polishing scanning electron microscope (Ar-SEM), and the pores of the Ar-SEM micrographs were quantitatively characterized by pores and cracks analysis system (PCAS). The results show that the pore types of the samples are mainly organic matter pores, intergranular pores, and intragranular pores. The pore sizes are mostly less than 100 nm, accounting for 72.70%-82.13%, and the mesopore ratios are 39.76%-45.48%, which is favorable for pore connectivity and gas migration. The pore structure becomes increasingly more complex with the increase of depth; but the deeper the layer, the more slowly the structural complexity increases with the increase of pore area.There is an inflection point in the vicinity of Ro, max=2 for the pore structure complexity. In the high maturity stage, the complexity of the pore structure gets increasingly lower with the increase of the maturity, and the structure complexity is lower as the pore area is larger; in the over mature stage, pore structure is increasingly more complex with the increase of maturity, and the larger the pore area, the greater the structural complexity.
2018, 43(5): 1611-1622.
doi: 10.3799/dqkx.2017.566
Abstract:
The investigations of nanopore heterogeneity in tectonically deformed coals are of significance for the study of occurrence state and transmission characteristics of coalbed methane (CBM). The low-middle rank tectonic deformed coals were screened out firstly in this study and then the matrix compressibility and the applicabilities of Menger, thermodynamics, Sierpinski, and FHH of tectonic deformed coals, as well as the fractal characteristics, were analyzed based on high-pressure mercury intrusion and low-pressure gas adsorption.The fractal curves of Menger model for mylonitic coals can be divided into three stages. However, for primary coals, cataclastic coals, schistose coals, scaly coals, and wrinkle coals, the fractal curves of Sierpinski, Menger, thermodynamics, and FHH can be obviously divided into two stages and the piecewise points locates at 100 nm, 72 nm, 72 596 nm, and 8 nm respectively. The fractal dimensions of Menger model are >3 and have a fitting deviation, so it is not suitable to characterize the pore heterogeneity. The Sierpinski model is suitable to characterize the fractal characteristics of the nanopore of the tectonic deformed coals whereas the FHH model is for the pores of 8-100 nm in primary coals and various tectonic deformed coals. The fractal dimension (Ds1) of micron pores at Sierpinski fractal curve (>100 nm) increases firstly and then decreases with the increase of tectonic deformation, reaching the highest values in schistose coals. The heterogeneity of both nanopores at Sierpinski fractal curve (< 100 nm, Ds2c) and that of pores of 8-100 nm at FHH fractal curve increase with the enhancement of the tectonic deformation. In primary coals and brittle deformed coals, Ds1 > Ds2c, indicating that the heterogeneity of micron pores are stronger than that of nanopores. In scaly coals, Ds1 is close to Ds2c. In wrinkle coals, Ds1 < Ds2c, indicating that the heterogeneity of nanopores is stronger than that of micron pores.
The investigations of nanopore heterogeneity in tectonically deformed coals are of significance for the study of occurrence state and transmission characteristics of coalbed methane (CBM). The low-middle rank tectonic deformed coals were screened out firstly in this study and then the matrix compressibility and the applicabilities of Menger, thermodynamics, Sierpinski, and FHH of tectonic deformed coals, as well as the fractal characteristics, were analyzed based on high-pressure mercury intrusion and low-pressure gas adsorption.The fractal curves of Menger model for mylonitic coals can be divided into three stages. However, for primary coals, cataclastic coals, schistose coals, scaly coals, and wrinkle coals, the fractal curves of Sierpinski, Menger, thermodynamics, and FHH can be obviously divided into two stages and the piecewise points locates at 100 nm, 72 nm, 72 596 nm, and 8 nm respectively. The fractal dimensions of Menger model are >3 and have a fitting deviation, so it is not suitable to characterize the pore heterogeneity. The Sierpinski model is suitable to characterize the fractal characteristics of the nanopore of the tectonic deformed coals whereas the FHH model is for the pores of 8-100 nm in primary coals and various tectonic deformed coals. The fractal dimension (Ds1) of micron pores at Sierpinski fractal curve (>100 nm) increases firstly and then decreases with the increase of tectonic deformation, reaching the highest values in schistose coals. The heterogeneity of both nanopores at Sierpinski fractal curve (< 100 nm, Ds2c) and that of pores of 8-100 nm at FHH fractal curve increase with the enhancement of the tectonic deformation. In primary coals and brittle deformed coals, Ds1 > Ds2c, indicating that the heterogeneity of micron pores are stronger than that of nanopores. In scaly coals, Ds1 is close to Ds2c. In wrinkle coals, Ds1 < Ds2c, indicating that the heterogeneity of nanopores is stronger than that of micron pores.
2018, 43(5): 1623-1634.
doi: 10.3799/dqkx.2018.416
Abstract:
Birnessite is a group of manganese oxide minerals widely found in nature. However, its ion exchange behavior and structural transformation have not been fully understood, and the characterization techniques are limited. To study the ion exchange behavior of birnessite and the reflection of structural transformation in Raman spectroscopy, triclinic Na-birnessite was synthesized using MnSO4 and NaOH, and ion exchange experiments on NH4+, K+, Mg2+, Ca2+, Ba2+, Co2+, and Zn2+ were carried out. Ion exchange birnessite samples were characterized using ICP-OES, XRD, and Raman spectroscopy. Raman study shows the relative strength of two stretching vibration modes in[MnO6] octahedra around 570-585 cm-1 and 640-655 cm-1 and the band location of the mode around 570-585 cm-1 are indicators of the symmetry of birnessite. High strength and frequency of the mode around 570-585 cm-1 are signs of triclinic symmetry. Raman bands around 280 cm-1 and 500 cm-1 are indicators of interlayer cations. If alkalis and alkaline-earth metals (i.e., Na+, K+, Mg2+, Ca2+, Ba2+, etc.) are in the interlayer of birnessite, a band around 280 cm-1 and two separate bands around 500 cm-1 will appear; whereas other interlayer cations only give rise to one single band at 500 cm-1, indicating disorder in the interlayer.
Birnessite is a group of manganese oxide minerals widely found in nature. However, its ion exchange behavior and structural transformation have not been fully understood, and the characterization techniques are limited. To study the ion exchange behavior of birnessite and the reflection of structural transformation in Raman spectroscopy, triclinic Na-birnessite was synthesized using MnSO4 and NaOH, and ion exchange experiments on NH4+, K+, Mg2+, Ca2+, Ba2+, Co2+, and Zn2+ were carried out. Ion exchange birnessite samples were characterized using ICP-OES, XRD, and Raman spectroscopy. Raman study shows the relative strength of two stretching vibration modes in[MnO6] octahedra around 570-585 cm-1 and 640-655 cm-1 and the band location of the mode around 570-585 cm-1 are indicators of the symmetry of birnessite. High strength and frequency of the mode around 570-585 cm-1 are signs of triclinic symmetry. Raman bands around 280 cm-1 and 500 cm-1 are indicators of interlayer cations. If alkalis and alkaline-earth metals (i.e., Na+, K+, Mg2+, Ca2+, Ba2+, etc.) are in the interlayer of birnessite, a band around 280 cm-1 and two separate bands around 500 cm-1 will appear; whereas other interlayer cations only give rise to one single band at 500 cm-1, indicating disorder in the interlayer.
2018, 43(5): 1635-1649.
doi: 10.3799/dqkx.2018.417
Abstract:
Detailed characterization and formation mechanism of the spinel exsolution in titanomagnetite is crucial for reconstructing the composition of magnetite solid solution precursor and for application to the Fe-Ti oxide oxythermometer. The chemical composition, topographic characteristics and crystallographic relationships of spinel exsolution were studied systematically to probe into its sequence and genetic mechanism through petrographic observation and the integrated use of in-situ microanalysis methods. The results show that there are three output forms of the spinel exsolution. One spinel exsolution is on the edge of the titanomagnetite with Mg# range from 60-70. Another is granular spinel exsolution distributing dispersedly with big particle-size, with Mg# range from 71-77. The third spinel exsolution is present as lamellae parallelling to the {100} of the titanomagnetite with Mg# range from 75-77. Three different types of spinel exsolution are all the magnesia-alumina spinel and have close-packed oxygen planes and directions parallel to those in the host magnetite with {111}Mag//{111}Spl, {110}Mag//{110}Spl and {100}Mag//{100}Spl respectively. Analysis suggests that three different types of spinel exsolution are all the product of the magnetite solid solution in the process of slow cooling with different sequence and genetic significance. The granular spinel exsolution in the titanomagnetite and the spinel exsolution on the edge of the titanomagnetite are related to some crystallographic defects in titanomagnetite and exsolved at the early stages of exsolution. The spinel lamellae exsolved in the way of spinodal decomposition parallelling to {l00}.
Detailed characterization and formation mechanism of the spinel exsolution in titanomagnetite is crucial for reconstructing the composition of magnetite solid solution precursor and for application to the Fe-Ti oxide oxythermometer. The chemical composition, topographic characteristics and crystallographic relationships of spinel exsolution were studied systematically to probe into its sequence and genetic mechanism through petrographic observation and the integrated use of in-situ microanalysis methods. The results show that there are three output forms of the spinel exsolution. One spinel exsolution is on the edge of the titanomagnetite with Mg# range from 60-70. Another is granular spinel exsolution distributing dispersedly with big particle-size, with Mg# range from 71-77. The third spinel exsolution is present as lamellae parallelling to the {100} of the titanomagnetite with Mg# range from 75-77. Three different types of spinel exsolution are all the magnesia-alumina spinel and have close-packed oxygen planes and directions parallel to those in the host magnetite with {111}Mag//{111}Spl, {110}Mag//{110}Spl and {100}Mag//{100}Spl respectively. Analysis suggests that three different types of spinel exsolution are all the product of the magnetite solid solution in the process of slow cooling with different sequence and genetic significance. The granular spinel exsolution in the titanomagnetite and the spinel exsolution on the edge of the titanomagnetite are related to some crystallographic defects in titanomagnetite and exsolved at the early stages of exsolution. The spinel lamellae exsolved in the way of spinodal decomposition parallelling to {l00}.
2018, 43(5): 1650-1662.
doi: 10.3799/dqkx.2018.418
Abstract:
In order to get a better understanding of the deep orebody information of Kaxiutata deposit in the Inner Mongolia, the groundwater particles were collected near the mining area. To have a contrast, the well water particles away from the mining area were also collected. It is found that the samples of groundwater in the mining area contain metal particles, and a high resolution transmission electron microscope was used to study these metal-bearing nanoparticles. The anomalous metal particles in the groundwater of this deposit are mainly Fe, Cu and Zn particles. The contents of Zn and Cu particles in the groundwater of the deposit are up to 80.3% and 22.7% respectively, and there are no Ag, Cu particles in the well samples in the background area, and the metal elements in the mining area are much higher than those in the well water. Metal-bearing nanoparticles and deep orebody (magnetite, pyrite, sphalerite, yellow copper ore, etc.) have a good correspondence. It is also proved that the groundwater containing metal particles from the deep orebody can carry the information of the deep orebody, which provides both a new perspective for the exploration of the deep concealed orebody and reference for the future exploration of the same type of deposit as well. In addition, the study also shows that the groundwater near the mining area may be affected by ore-forming particles, which may also affect the quality of underground drinking water, and the research method of groundwater containing metal particles can also be used to detect contamination of underground drinking water.
In order to get a better understanding of the deep orebody information of Kaxiutata deposit in the Inner Mongolia, the groundwater particles were collected near the mining area. To have a contrast, the well water particles away from the mining area were also collected. It is found that the samples of groundwater in the mining area contain metal particles, and a high resolution transmission electron microscope was used to study these metal-bearing nanoparticles. The anomalous metal particles in the groundwater of this deposit are mainly Fe, Cu and Zn particles. The contents of Zn and Cu particles in the groundwater of the deposit are up to 80.3% and 22.7% respectively, and there are no Ag, Cu particles in the well samples in the background area, and the metal elements in the mining area are much higher than those in the well water. Metal-bearing nanoparticles and deep orebody (magnetite, pyrite, sphalerite, yellow copper ore, etc.) have a good correspondence. It is also proved that the groundwater containing metal particles from the deep orebody can carry the information of the deep orebody, which provides both a new perspective for the exploration of the deep concealed orebody and reference for the future exploration of the same type of deposit as well. In addition, the study also shows that the groundwater near the mining area may be affected by ore-forming particles, which may also affect the quality of underground drinking water, and the research method of groundwater containing metal particles can also be used to detect contamination of underground drinking water.
2018, 43(5): 1663-1669.
doi: 10.3799/dqkx.2018.419
Abstract:
To reveal the change of C atom lattice arrangements in coal-based graphite, samples with different metamorphic grades from several areas, such as Shaanxi Fengxian, Hunan Xinhua and Hunan Lutang, were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and Raman spectrum (Raman). The results show that the metamorphism degree of Fengxian graphite is in the stage of super anthracite, and that of Xinhua is semi-graphite.The graphitization degree of samples from Lutang is the highest, and its structure is close to the three dimensions ordered ideal graphite, but a little of disordered domain still exists in the structure of Lutang graphite. XRD shows that the distance between C atom layers decreases with graphitization degree increasing, but the numbers of layers and the area of single layers increase. The G peak in the Raman spectrum is gradually stronger and sharper while the D peak is weaker, and the intensity ratio and area ratio of D peak and G peak are all reduced with the graphitization increasing, which demonstrates the increasing sp2 planar area. The lattice images of TEM show that the graphite-like pillars were formed at first in the graphitization, and then these pillars were united laterally with each other to form the graphite lattice structure.
To reveal the change of C atom lattice arrangements in coal-based graphite, samples with different metamorphic grades from several areas, such as Shaanxi Fengxian, Hunan Xinhua and Hunan Lutang, were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and Raman spectrum (Raman). The results show that the metamorphism degree of Fengxian graphite is in the stage of super anthracite, and that of Xinhua is semi-graphite.The graphitization degree of samples from Lutang is the highest, and its structure is close to the three dimensions ordered ideal graphite, but a little of disordered domain still exists in the structure of Lutang graphite. XRD shows that the distance between C atom layers decreases with graphitization degree increasing, but the numbers of layers and the area of single layers increase. The G peak in the Raman spectrum is gradually stronger and sharper while the D peak is weaker, and the intensity ratio and area ratio of D peak and G peak are all reduced with the graphitization increasing, which demonstrates the increasing sp2 planar area. The lattice images of TEM show that the graphite-like pillars were formed at first in the graphitization, and then these pillars were united laterally with each other to form the graphite lattice structure.
2018, 43(5): 1670-1679.
doi: 10.3799/dqkx.2018.420
Abstract:
A nanomineral material was prepared from thermally treated low grade natural rhodochrosite in this study. The composition of natural rhodochrosite was investigated by combining XRF, TEM and chemical method. The substance and structure after calcination were characterized by TG-MS, XRD, SEM, BET, and XPS. The results show that the mineral constituents of the rhodochrosite ore are rhodochrosite, quartz, pyrite and sulfate oxidized from pyrite. When the temperature increases to 550℃, the rhodochrosite calcines gradually, releasing a great amount of CO2, forming hausmannite and other species of MnOx. As a result, the porous structure (massive accumulation) occurs on the surface of rhodochrosite, which has the pore sizes in 3-7 nanometer, in particular, the maximum specific surface area is 31.5 m2/g. NH3-SCR results show that the sample R550 exhibited a high denitration performance. R550 also has a good removal efficiency of cadmium, lead and copper ions. It is indicated that the nano-porous material with better specific surface area can be prepared through calcining rhodochrosite ore at 550℃.
A nanomineral material was prepared from thermally treated low grade natural rhodochrosite in this study. The composition of natural rhodochrosite was investigated by combining XRF, TEM and chemical method. The substance and structure after calcination were characterized by TG-MS, XRD, SEM, BET, and XPS. The results show that the mineral constituents of the rhodochrosite ore are rhodochrosite, quartz, pyrite and sulfate oxidized from pyrite. When the temperature increases to 550℃, the rhodochrosite calcines gradually, releasing a great amount of CO2, forming hausmannite and other species of MnOx. As a result, the porous structure (massive accumulation) occurs on the surface of rhodochrosite, which has the pore sizes in 3-7 nanometer, in particular, the maximum specific surface area is 31.5 m2/g. NH3-SCR results show that the sample R550 exhibited a high denitration performance. R550 also has a good removal efficiency of cadmium, lead and copper ions. It is indicated that the nano-porous material with better specific surface area can be prepared through calcining rhodochrosite ore at 550℃.
2018, 43(5): 1680-1690.
doi: 10.3799/dqkx.2018.421
Abstract:
Nanoparticles (NPs) are more toxic than larger particles at the same mass concentration. Therefore, it should be paid more attention by researchers. In addition to 87 previous papers with valid data on NPs, some results obtained by our research group are also adopted in this paper. The study methods of number concentrations, size distribution, chemical compositions, health effects, source, formation and removal mechanism of NPs, are summarized and reviewed in this study. It is identified the following priorities for further research and provided suggestions when studying NPs in China:(1) systematic study of physicochemical characteristics and routine monitoring of ambient and source NPs; (2) systematic study on the formation mechanism of NPs; (3) development of the integrated off-line and online source apportionment methods of NPs; (4) systematic establishment of sampling and analytical methods for NPs studies; (5) strengthening study on toxicology, epidemiology and protection methods of NPs. It is suggested that it may greatly increase the concentration of nanoparticles when decreasing TSP and PM2.5 which leads to serious health troubles, and government should make more efforts to support the study on the source apportionment and control of nanoparticles.
Nanoparticles (NPs) are more toxic than larger particles at the same mass concentration. Therefore, it should be paid more attention by researchers. In addition to 87 previous papers with valid data on NPs, some results obtained by our research group are also adopted in this paper. The study methods of number concentrations, size distribution, chemical compositions, health effects, source, formation and removal mechanism of NPs, are summarized and reviewed in this study. It is identified the following priorities for further research and provided suggestions when studying NPs in China:(1) systematic study of physicochemical characteristics and routine monitoring of ambient and source NPs; (2) systematic study on the formation mechanism of NPs; (3) development of the integrated off-line and online source apportionment methods of NPs; (4) systematic establishment of sampling and analytical methods for NPs studies; (5) strengthening study on toxicology, epidemiology and protection methods of NPs. It is suggested that it may greatly increase the concentration of nanoparticles when decreasing TSP and PM2.5 which leads to serious health troubles, and government should make more efforts to support the study on the source apportionment and control of nanoparticles.
2018, 43(5): 1691-1708.
doi: 10.3799/dqkx.2018.422
Abstract:
Airborne particulate matter, especially the fine particles PM2.5, is an important component of ambient air. Airborne particles have serious impacts on human health due to their association with toxic matters. They can also exert important effects on environment and climate through hygroscopic growth, cloud condensation nuclei activity and light absorption and scattering. The long range transport of particulate matter can affect the regional and global geochemical cycle. In this paper, physical and chemical characteristics of airborne particles are discussed and the on-line and off-line analytical techniques are introduced. In addition, application of source apportionment methods has been evaluated and the effects of airborne particles on environment, climate, human health, and global geochemical cycle have been expounded. Finally, the research prospect of airborne particles is presented.
Airborne particulate matter, especially the fine particles PM2.5, is an important component of ambient air. Airborne particles have serious impacts on human health due to their association with toxic matters. They can also exert important effects on environment and climate through hygroscopic growth, cloud condensation nuclei activity and light absorption and scattering. The long range transport of particulate matter can affect the regional and global geochemical cycle. In this paper, physical and chemical characteristics of airborne particles are discussed and the on-line and off-line analytical techniques are introduced. In addition, application of source apportionment methods has been evaluated and the effects of airborne particles on environment, climate, human health, and global geochemical cycle have been expounded. Finally, the research prospect of airborne particles is presented.
2018, 43(5): 1709-1724.
doi: 10.3799/dqkx.2018.423
Abstract:
This paper presents the characteristics of atmospheric aerosols, the interfacial reaction between particles and the significance of coevolution of minerals, focusing on the size distribution and mineral composition of atmospheric particles, and characteristics of the products and key chemical processes of the interfacial reaction between the atmospheric particles and common toxic and harmful gases. In addition, the convergence role, adjustment mechanism, and catalystic effect of mineral particles on the aerosol formation process, and the synergistic reaction mechanism between SO2 and NOx in the atmosphere are summarized. Furthermore, the effects of micro/nano particles on the formation of secondary organic aerosols and the combination and coevolution of interfacial reaction products between atmospheric and mineral phases are analyzed. This review can provide guidance for further research on the process of atmospheric particulate matter reacting with trace polluted gases in the atmosphere to form secondary aerosols and then affecting the chemical composition of the atmosphere, and it is also of environmental significance since it facilitates future studies of both the micro-interface chemistry reaction of the surface characteristics of the atmospheric mineral particles in the complex pollutants and the combined effects of mineral dust-pollutant aerosol system in fog-haze formation, transformation, particle production and blocking behavior.
This paper presents the characteristics of atmospheric aerosols, the interfacial reaction between particles and the significance of coevolution of minerals, focusing on the size distribution and mineral composition of atmospheric particles, and characteristics of the products and key chemical processes of the interfacial reaction between the atmospheric particles and common toxic and harmful gases. In addition, the convergence role, adjustment mechanism, and catalystic effect of mineral particles on the aerosol formation process, and the synergistic reaction mechanism between SO2 and NOx in the atmosphere are summarized. Furthermore, the effects of micro/nano particles on the formation of secondary organic aerosols and the combination and coevolution of interfacial reaction products between atmospheric and mineral phases are analyzed. This review can provide guidance for further research on the process of atmospheric particulate matter reacting with trace polluted gases in the atmosphere to form secondary aerosols and then affecting the chemical composition of the atmosphere, and it is also of environmental significance since it facilitates future studies of both the micro-interface chemistry reaction of the surface characteristics of the atmospheric mineral particles in the complex pollutants and the combined effects of mineral dust-pollutant aerosol system in fog-haze formation, transformation, particle production and blocking behavior.
2018, 43(5): 1725-1736.
doi: 10.3799/dqkx.2018.424
Abstract:
Perfluorinated compounds (PFCs) are one type of anionic surfactants containing strong-polar carbon-fluorine bonds.PFCs widely exist in aqueous environment because of their high solubility and stability, which has potential risk to human health due to the high bioaccumulation and potential toxicity. Recently, various methods have been developed to remove PFCs from aquatic environment. Compared with bulk materials, nano-materials have higher reactivity because of their special structure. In this paper, it presents some nano-materials such as carbon nanotube, modified clay minerals, nano-TiO2, In2O3, Ga2O3, etc., which have been applied for adsorption, nanofiltration, photochemistry, electrochemistry, etc. Their advantages, disadvantages and mechanism are compared in detail. Besides, it also discusses the issues and prospects for PFCs removal from water by nanomaterials.
Perfluorinated compounds (PFCs) are one type of anionic surfactants containing strong-polar carbon-fluorine bonds.PFCs widely exist in aqueous environment because of their high solubility and stability, which has potential risk to human health due to the high bioaccumulation and potential toxicity. Recently, various methods have been developed to remove PFCs from aquatic environment. Compared with bulk materials, nano-materials have higher reactivity because of their special structure. In this paper, it presents some nano-materials such as carbon nanotube, modified clay minerals, nano-TiO2, In2O3, Ga2O3, etc., which have been applied for adsorption, nanofiltration, photochemistry, electrochemistry, etc. Their advantages, disadvantages and mechanism are compared in detail. Besides, it also discusses the issues and prospects for PFCs removal from water by nanomaterials.
2018, 43(5): 1737-1745.
doi: 10.3799/dqkx.2018.425
Abstract:
Soil heavy metal contamination is one of the key environmental problems around the world and the application of nanomaterials in soil heavy metal remediation has gained increasing attention in recent years. In this paper, nanomaterial/modified nanomaterial application, application of nanotechnology combined with other soil remediation technologies and main factors affecting the nanomaterials application in soil heavy metal remediation are summarized. It is suggested that new nanomaterials should be developed which feature the enhanced diffusion in soil, and fast transformation from laboratory experiments to field applications. In addition, environmental behavior of the nanomaterials and their remediation mechanism should be explored. This paper will help to fully understand and further promote the application of nanomaterials in soil heavy metal remediation.
Soil heavy metal contamination is one of the key environmental problems around the world and the application of nanomaterials in soil heavy metal remediation has gained increasing attention in recent years. In this paper, nanomaterial/modified nanomaterial application, application of nanotechnology combined with other soil remediation technologies and main factors affecting the nanomaterials application in soil heavy metal remediation are summarized. It is suggested that new nanomaterials should be developed which feature the enhanced diffusion in soil, and fast transformation from laboratory experiments to field applications. In addition, environmental behavior of the nanomaterials and their remediation mechanism should be explored. This paper will help to fully understand and further promote the application of nanomaterials in soil heavy metal remediation.
2018, 43(5): 1746-1754.
doi: 10.3799/dqkx.2018.426
Abstract:
Fault gouge is one of the most obvious material indicators in seismogenic fault zone, and it retains a wealth of information of fault activities. Based on field investigation and observation under microscope, nano/micro-scale deformation styles of clay minerals in seismogenic fault zone were analyzed in detail and discussed in this paper by use of SEM technology. The clay minerals are arranged in alignment during stick-slipping, and exhibit parallel extinction zones under orthogonal polarization microscope. In the view of SEM, the directional arrangement of flake clay minerals can be observed, and multiple stick-slipping events on the principle sliding zone can be clearly identified. Moreover, it is found that the creep-slipping phenomena in fault gouges are universal. In the microscopic view, clay minerals exhibit wavelike extinction zones. In the view of SEM, fold deformation, wavelike deformation, sliding around the gravels and entangling deformation of flake clay minerals can be observed. As stick-slipping and creep-slipping indications can be observed in the same view, and by analyzing their temporal relationship, it is found that the creep-slipping occurs before the stick-slipping and corresponds to the movement in the meta-instability stage of fault sliding.
Fault gouge is one of the most obvious material indicators in seismogenic fault zone, and it retains a wealth of information of fault activities. Based on field investigation and observation under microscope, nano/micro-scale deformation styles of clay minerals in seismogenic fault zone were analyzed in detail and discussed in this paper by use of SEM technology. The clay minerals are arranged in alignment during stick-slipping, and exhibit parallel extinction zones under orthogonal polarization microscope. In the view of SEM, the directional arrangement of flake clay minerals can be observed, and multiple stick-slipping events on the principle sliding zone can be clearly identified. Moreover, it is found that the creep-slipping phenomena in fault gouges are universal. In the microscopic view, clay minerals exhibit wavelike extinction zones. In the view of SEM, fold deformation, wavelike deformation, sliding around the gravels and entangling deformation of flake clay minerals can be observed. As stick-slipping and creep-slipping indications can be observed in the same view, and by analyzing their temporal relationship, it is found that the creep-slipping occurs before the stick-slipping and corresponds to the movement in the meta-instability stage of fault sliding.
2018, 43(5): 1755-1762.
doi: 10.3799/dqkx.2018.427
Abstract:
In order to study the characteristics of nanometer pore structure of coal, the heterogeneous structures of nano pores of different rank coals were investigated by using SEM, liquid nitrogen adsorption and small angle X ray. It is found that the mesopore shows the multimodal division, mainly concentrated in the 2-10 aperture and nm. The adsorption capacity of coal low-temperature nitrogen adsorption experiments of coal samples is 3.676 cm3/g, and coal sample surface area is 1.416 m2/g. By analyzing the most probable aperture, the range of experimental pressure can be found out, and the most probable pore size will be increased with the adsorbent pressure. Gas diffusion model in most nanoscale pore structure model prefers coals mainly concentrated on transitional diffusion. In more developed microporous coal samples (anthracite), the diffusion type is closer to the Knudsen diffusion. In much less developed coal samples, the main diffusion type is closer to Fick diffusion. The Knudsen number is negatively related to temperature, and Knudsen number tends to be stable when the temperature is higher than 250 K, which is positively correlated with the pressure. The diffusion will be easier with the increase of pressure.
In order to study the characteristics of nanometer pore structure of coal, the heterogeneous structures of nano pores of different rank coals were investigated by using SEM, liquid nitrogen adsorption and small angle X ray. It is found that the mesopore shows the multimodal division, mainly concentrated in the 2-10 aperture and nm. The adsorption capacity of coal low-temperature nitrogen adsorption experiments of coal samples is 3.676 cm3/g, and coal sample surface area is 1.416 m2/g. By analyzing the most probable aperture, the range of experimental pressure can be found out, and the most probable pore size will be increased with the adsorbent pressure. Gas diffusion model in most nanoscale pore structure model prefers coals mainly concentrated on transitional diffusion. In more developed microporous coal samples (anthracite), the diffusion type is closer to the Knudsen diffusion. In much less developed coal samples, the main diffusion type is closer to Fick diffusion. The Knudsen number is negatively related to temperature, and Knudsen number tends to be stable when the temperature is higher than 250 K, which is positively correlated with the pressure. The diffusion will be easier with the increase of pressure.
2018, 43(5): 1763-1772.
doi: 10.3799/dqkx.2018.428
Abstract:
How metal mineral grows in hydrothermal fluids from a metal ion or metallic compound to the macrocrystals is one of the most fundamental problems in mineralogy and metallogeny. In this study, a series of non-isothermal and non-isochronic hydrolysis experiments of potassium titanium fluoride (K2TiF6) solution were investigated at temperatures from 200 to 400℃ and pressure of 100 MPa. The results show that anatases, with varied morphology, were synthetized in the hydrothermal conditions. With increasing reactive time and temperature, the anatase can grow up from dozens of nanometers to 10 micrometers or more. Remarkably, the anatases that were synthetized within 10 h or at higher temperatures exceeds those over 10 h or at lower temperatures in the rate of growth, which suggests the supersaturation level of Ti and temperature dependence on the crystal morphology, grain size and the rate of growth of the anatase. Generally speaking, classical nucleation and growth, oriented attachment, and Ostwald ripening are involved in the growth of the hydrothermal anatase, in which the supersaturation level of metal in hydrothermal fluids and dissolution-precipitation process are decisive to control the rate of anatase growth. Finally, we consider anatase as a typomorphic mineral that its morphology could be used to decipher the formation temperature, generation relationship of minerals, and even the evolution of F-bearing hydrothermal fluids.
How metal mineral grows in hydrothermal fluids from a metal ion or metallic compound to the macrocrystals is one of the most fundamental problems in mineralogy and metallogeny. In this study, a series of non-isothermal and non-isochronic hydrolysis experiments of potassium titanium fluoride (K2TiF6) solution were investigated at temperatures from 200 to 400℃ and pressure of 100 MPa. The results show that anatases, with varied morphology, were synthetized in the hydrothermal conditions. With increasing reactive time and temperature, the anatase can grow up from dozens of nanometers to 10 micrometers or more. Remarkably, the anatases that were synthetized within 10 h or at higher temperatures exceeds those over 10 h or at lower temperatures in the rate of growth, which suggests the supersaturation level of Ti and temperature dependence on the crystal morphology, grain size and the rate of growth of the anatase. Generally speaking, classical nucleation and growth, oriented attachment, and Ostwald ripening are involved in the growth of the hydrothermal anatase, in which the supersaturation level of metal in hydrothermal fluids and dissolution-precipitation process are decisive to control the rate of anatase growth. Finally, we consider anatase as a typomorphic mineral that its morphology could be used to decipher the formation temperature, generation relationship of minerals, and even the evolution of F-bearing hydrothermal fluids.
2018, 43(5): 1773-1782.
doi: 10.3799/dqkx.2018.429
Abstract:
Mineral compositions of complex reservoir are characterized by heterogeneity and small pore structure. Oil and gas exploration on complex reservoirs are determined by evaluations of reserving space, rock structure, fluid saturation and migration. Two-and three-dimensional space distribution of pore throat can be depicted precisely by multiscale CT and FIB-SEM, XRF and Qemscan can assess mineral compositions and distribution, fluid saturation and migration can be observed by multi-scale CT-ESEM, selecting sample target step by step, forming work flow on pore-mineral-fluid three-dimensional quantitative analysis, analysis scale across 6-7 orders of magnitude. Writing digital rock analysis software modules, dividing precisely micro pore throat three-dimensional distribution, assessing quantitatively on effective reservoir connectivity, establishing quantitative analysis methods of heterogeneity samples scales and pore-seam spatial configuration, can provide the basis for complex reservoir fluid percolation ability evaluation. To carry out the research on shale oil saturation and migration physical simulation which is based on nano porous materials, to compound adjustable nanomaterials in some respects such as pore size, wettability and surface microstructure, to imitate shale oil reservoir, we can find out the impact of each factor on shale oil saturation and pore size lower limit where fluid could migrate. Extracting key parameters based on hole network model of real core, carrying out the research on the best path of oil and gas migration using lattice boltzmann and finite element modelling, molecular simulation is used for the study on oil and gas aggregation mechanism and diffusion potential in inorganic and organic nano pores. Finally we could uncover the oil and gas flow mechanism in micro-nano reservoir space, and provide technical support for the effective assessment of shale oil and gas, tight sandstone and complex resesvoirs, and quantitative evaluation of oil-gas possibility.
Mineral compositions of complex reservoir are characterized by heterogeneity and small pore structure. Oil and gas exploration on complex reservoirs are determined by evaluations of reserving space, rock structure, fluid saturation and migration. Two-and three-dimensional space distribution of pore throat can be depicted precisely by multiscale CT and FIB-SEM, XRF and Qemscan can assess mineral compositions and distribution, fluid saturation and migration can be observed by multi-scale CT-ESEM, selecting sample target step by step, forming work flow on pore-mineral-fluid three-dimensional quantitative analysis, analysis scale across 6-7 orders of magnitude. Writing digital rock analysis software modules, dividing precisely micro pore throat three-dimensional distribution, assessing quantitatively on effective reservoir connectivity, establishing quantitative analysis methods of heterogeneity samples scales and pore-seam spatial configuration, can provide the basis for complex reservoir fluid percolation ability evaluation. To carry out the research on shale oil saturation and migration physical simulation which is based on nano porous materials, to compound adjustable nanomaterials in some respects such as pore size, wettability and surface microstructure, to imitate shale oil reservoir, we can find out the impact of each factor on shale oil saturation and pore size lower limit where fluid could migrate. Extracting key parameters based on hole network model of real core, carrying out the research on the best path of oil and gas migration using lattice boltzmann and finite element modelling, molecular simulation is used for the study on oil and gas aggregation mechanism and diffusion potential in inorganic and organic nano pores. Finally we could uncover the oil and gas flow mechanism in micro-nano reservoir space, and provide technical support for the effective assessment of shale oil and gas, tight sandstone and complex resesvoirs, and quantitative evaluation of oil-gas possibility.
2018, 43(5): 1783-1791.
doi: 10.3799/dqkx.2018.430
Abstract:
The mechanism of shale gas adsorption is the theoretical foundation for elucidating the adsorption and transformation conditions, and establishing a universal quantitative evaluation model. The adsorption behavior of CH4 and CO2 in illite slit pores with different sizes under various temperature and pressure conditions was simulated by GCMC (Grand Canonical Monte Carlo) method. It is found that adsorption capacities obtained from both molecular simulation and experiments have the same connotations and are comparable when being normalized to the surface area, under which conditions the molecular simulation results are consistent with the experimental measurements. In this way, the basis for the study of adsorption behavior and mechanism of shale gas is established by molecular simulation:the internal cause (mechanism) of gas adsorption on the mineral surface is van der Waals force and Coulomb force in gas-solid molecules, the larger adsorption capacity of CO2 than CH4 on the surface of the illite is the reflection of a higher binding energy; the adsorption of CH4 and CO2 on the illite is not rigorous monolayer-adsorption, but a strong adsorption layer mainly; the adsorption phase density will overlap when pore size reduced to micropore, and microporous filling is thus formed, which is also a result from the superposition of their binding energy.
The mechanism of shale gas adsorption is the theoretical foundation for elucidating the adsorption and transformation conditions, and establishing a universal quantitative evaluation model. The adsorption behavior of CH4 and CO2 in illite slit pores with different sizes under various temperature and pressure conditions was simulated by GCMC (Grand Canonical Monte Carlo) method. It is found that adsorption capacities obtained from both molecular simulation and experiments have the same connotations and are comparable when being normalized to the surface area, under which conditions the molecular simulation results are consistent with the experimental measurements. In this way, the basis for the study of adsorption behavior and mechanism of shale gas is established by molecular simulation:the internal cause (mechanism) of gas adsorption on the mineral surface is van der Waals force and Coulomb force in gas-solid molecules, the larger adsorption capacity of CO2 than CH4 on the surface of the illite is the reflection of a higher binding energy; the adsorption of CH4 and CO2 on the illite is not rigorous monolayer-adsorption, but a strong adsorption layer mainly; the adsorption phase density will overlap when pore size reduced to micropore, and microporous filling is thus formed, which is also a result from the superposition of their binding energy.
2018, 43(5): 1792-1816.
doi: 10.3799/dqkx.2018.431
Abstract:
Shale gas will become an important energy source in China in the near future. However, most shale gas in China is deeply buried, so the experience of shallow-seated shale gas exploitation in US can not be directly employed. A better understanding of shale gas transport mechanism can surely facilitate the precise prediction of production and the exploitation optimization of deep-seated shale gas. In this paper, we establish a multiscale simulation method named pore-field iteration. Field-scale problems such as inflow performance relationship and decline curve analysis are solved based on pore-scale simulation directly. In addition, the coupling between the high Knudsen number effect in micro flow and the non-ideal gas effect caused by the high pressure and temperature underground is investigated from a theoretical perspective. Finally, we incorporate the influence of the elastic structural deformation in our modeling and propose the characteristic pressure model to calculate apparent permeability, which supports shale gas exploitation by providing theoretical analysis.
Shale gas will become an important energy source in China in the near future. However, most shale gas in China is deeply buried, so the experience of shallow-seated shale gas exploitation in US can not be directly employed. A better understanding of shale gas transport mechanism can surely facilitate the precise prediction of production and the exploitation optimization of deep-seated shale gas. In this paper, we establish a multiscale simulation method named pore-field iteration. Field-scale problems such as inflow performance relationship and decline curve analysis are solved based on pore-scale simulation directly. In addition, the coupling between the high Knudsen number effect in micro flow and the non-ideal gas effect caused by the high pressure and temperature underground is investigated from a theoretical perspective. Finally, we incorporate the influence of the elastic structural deformation in our modeling and propose the characteristic pressure model to calculate apparent permeability, which supports shale gas exploitation by providing theoretical analysis.
