2009 Vol. 34, No. 3
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2009, 34(3): 387-391.
Abstract:
The rare samples of garnet bearing peridotites (GBPs), either from alkaline volcanics or from orogenic belt, provide important information of the evolution of subcontinental lithospheric upper mantle. Cenozoic volcanic rocks widely spread in eastern China, and GBPs occur in the volcanic fields of Mingxi, Xilong, Hebi, Nüshan, Hannuoba and Chaoerhe. According to the occurrence of spinel, the mantle xenoliths from above volcanic fields can be divided into two groups as Gt peridotite and Gt/Sp peridotite. Electronic probe data reveal the P-T conditions of these xenoiths as (1) Gt peridotite from depths over 70 km, and (2) Gt/Sp peridotite from 55-70 km. Meanwhile, orogenic garnets from Dabie-Sulu UHP belt also facilitate the understanding of the subcontinental lithospheric upper mantle of eastern China. Variations of garnets in the Gt lherzolite from the UHP belt record the evolution of subduction from Al-rich Gt (70-120 km) to Al-poor Gt (> 120-150 km). Garnets and their metamorphic reactions reveal the mantle compositions and evolution in eastern China.
The rare samples of garnet bearing peridotites (GBPs), either from alkaline volcanics or from orogenic belt, provide important information of the evolution of subcontinental lithospheric upper mantle. Cenozoic volcanic rocks widely spread in eastern China, and GBPs occur in the volcanic fields of Mingxi, Xilong, Hebi, Nüshan, Hannuoba and Chaoerhe. According to the occurrence of spinel, the mantle xenoliths from above volcanic fields can be divided into two groups as Gt peridotite and Gt/Sp peridotite. Electronic probe data reveal the P-T conditions of these xenoiths as (1) Gt peridotite from depths over 70 km, and (2) Gt/Sp peridotite from 55-70 km. Meanwhile, orogenic garnets from Dabie-Sulu UHP belt also facilitate the understanding of the subcontinental lithospheric upper mantle of eastern China. Variations of garnets in the Gt lherzolite from the UHP belt record the evolution of subduction from Al-rich Gt (70-120 km) to Al-poor Gt (> 120-150 km). Garnets and their metamorphic reactions reveal the mantle compositions and evolution in eastern China.
2009, 34(3): 392-398.
Abstract:
The 10Å-manganate is main mineral component of the marine diagenetic nodule and terraneous manganese. The previous study has poved that the transition metals—copper, nickel paly an improtant role in the stability of 10Å-manganates. However, the geochemical behavior of sodium ions is seldom invovled in the previous researches. The role of sodium ions on the stability of 10Å-manganates was investigated in terms of the selective dissolution experiments and adsorption experiments as well as crystal chemistry and mineralogy by using the marine diagenetic nodule recovered near the equatorial East Pacific. Sodium ions in 10Å-manganates can be extracted by weak acidic and 10Å-manganates transform into 7Å-manganates. On the other hand, crystallinity of the samples whose sodium ions were extracted turned better and some non-10Å-manganates phases turned into 10Å-manganates through the uptake of sodium. The destructive structure of 10Å-manganates can't recover thoroughly from the uptake of sodium ions under natural conditions. Sodium ions play an important role in the stability of 10Å-manganates of marine diagenetic nodule.
The 10Å-manganate is main mineral component of the marine diagenetic nodule and terraneous manganese. The previous study has poved that the transition metals—copper, nickel paly an improtant role in the stability of 10Å-manganates. However, the geochemical behavior of sodium ions is seldom invovled in the previous researches. The role of sodium ions on the stability of 10Å-manganates was investigated in terms of the selective dissolution experiments and adsorption experiments as well as crystal chemistry and mineralogy by using the marine diagenetic nodule recovered near the equatorial East Pacific. Sodium ions in 10Å-manganates can be extracted by weak acidic and 10Å-manganates transform into 7Å-manganates. On the other hand, crystallinity of the samples whose sodium ions were extracted turned better and some non-10Å-manganates phases turned into 10Å-manganates through the uptake of sodium. The destructive structure of 10Å-manganates can't recover thoroughly from the uptake of sodium ions under natural conditions. Sodium ions play an important role in the stability of 10Å-manganates of marine diagenetic nodule.
2009, 34(3): 399-404.
Abstract:
Characteristics of current crustal movement in Qinghai-Tibet Plateau were analyzed with least square collusion and wavelet using GPS data, and crustal movement strength and vortex movement were analyzed quantitatively.The conclusions are drawn as follows: The crustal movement strength in Qinghai-Tibet Plateau decreases from west to east along arc tectonic ruptures formed by Kala-Kunlun, Mani, Yushu, Xianshuihe and Xiaojiang faults.The crustal movement strengths in north and west are stronger than those of south and east in the Sichuan-Yunnan block, of which east boundaries are obvious, and west boundaries are not.There are three vortex zones in Qinghai-Tibet Plateau.Firstly, Lhasa, Qiangtang, and mid-west of Sichuan-Yunnan region clockwisely rotate, and areas to east of Yadong-Gulu are high-value areas.Secondly, Qaidam block and that to its north counterclockwisely rotate, and high-value areas are between West Kunlun and Altun.Thirdly, the boundaries of Qinghai-Tibet Plateau and southern China block counterclockwisely rotate, and high-value areas are in the corner of Longmenshan and Anninghe.
Characteristics of current crustal movement in Qinghai-Tibet Plateau were analyzed with least square collusion and wavelet using GPS data, and crustal movement strength and vortex movement were analyzed quantitatively.The conclusions are drawn as follows: The crustal movement strength in Qinghai-Tibet Plateau decreases from west to east along arc tectonic ruptures formed by Kala-Kunlun, Mani, Yushu, Xianshuihe and Xiaojiang faults.The crustal movement strengths in north and west are stronger than those of south and east in the Sichuan-Yunnan block, of which east boundaries are obvious, and west boundaries are not.There are three vortex zones in Qinghai-Tibet Plateau.Firstly, Lhasa, Qiangtang, and mid-west of Sichuan-Yunnan region clockwisely rotate, and areas to east of Yadong-Gulu are high-value areas.Secondly, Qaidam block and that to its north counterclockwisely rotate, and high-value areas are between West Kunlun and Altun.Thirdly, the boundaries of Qinghai-Tibet Plateau and southern China block counterclockwisely rotate, and high-value areas are in the corner of Longmenshan and Anninghe.
2009, 34(3): 405-411.
Abstract:
The composition, features and geological time of the flora in the Anyuan Formation, Shangrao City, Jiangxi Province have been studied. The fossil plants obtained are identified to be of 60 species belonging to 28 genera: 26 known species, 10 similar species and 24 undetermined species. Of the Anyuan flora, Cycadophytes accounts for 55%, Pteridphytes, 18. 3%, Pteridospermophytes, 10%, Ginkgophytes, 8. 3%, Coniferophytes, 3.4%. The flora should be classified as Ptilozamites-Asthrophyopsis assemblage in the lower part of the Dictyophyllum-Clathropteris series. This important Upper Triassic flora is widely distributed in Sweden, Germany, eastern Greenland, Russia, Vietnam and Japan. In China, it has been found in the Xujiahe Formation of Sichuan, Shazhenxi Formation of Hubei, Lalijian Formation of Anhui, Fanjiatang Formation of Jiangsu, Dakeng Formation of Fujian, Wuzao Formation of Zhejiang and so on. The philotherm of the flora represents hot and semi hu mid climate of South Ch/na coastal areas.
The composition, features and geological time of the flora in the Anyuan Formation, Shangrao City, Jiangxi Province have been studied. The fossil plants obtained are identified to be of 60 species belonging to 28 genera: 26 known species, 10 similar species and 24 undetermined species. Of the Anyuan flora, Cycadophytes accounts for 55%, Pteridphytes, 18. 3%, Pteridospermophytes, 10%, Ginkgophytes, 8. 3%, Coniferophytes, 3.4%. The flora should be classified as Ptilozamites-Asthrophyopsis assemblage in the lower part of the Dictyophyllum-Clathropteris series. This important Upper Triassic flora is widely distributed in Sweden, Germany, eastern Greenland, Russia, Vietnam and Japan. In China, it has been found in the Xujiahe Formation of Sichuan, Shazhenxi Formation of Hubei, Lalijian Formation of Anhui, Fanjiatang Formation of Jiangsu, Dakeng Formation of Fujian, Wuzao Formation of Zhejiang and so on. The philotherm of the flora represents hot and semi hu mid climate of South Ch/na coastal areas.
2009, 34(3): 412-418.
Abstract:
Sporopollen, ostracod and ichnofabric characteristics of Neogene in the Qikou depression were studied and fifty-three genus were recognized. Two sporopollen combination, Magnastites-Ulmus-Taxodiaceae pollenites and Polygonaceae-Chenopodiaceae, were established.Twelve genus ostracod were identified.The ostracod shell is singleness, thin and slippy, which exhibites the visage of typical freshwater ostracod.Four ichnofabric were identified, which are Scoyenia ichnofabric, Skolithos ichnofabric, Palaeophycus ichnofabric and acute disturb ichnofabric respectively.Based on the above research, five biofacies and ichnofacies were carved up, which represent overflow plain, small lake in the overflow plain, interchannel or subaqueous spreader interchannel, shallow lake and predelta sedimentary environments respectively.
Sporopollen, ostracod and ichnofabric characteristics of Neogene in the Qikou depression were studied and fifty-three genus were recognized. Two sporopollen combination, Magnastites-Ulmus-Taxodiaceae pollenites and Polygonaceae-Chenopodiaceae, were established.Twelve genus ostracod were identified.The ostracod shell is singleness, thin and slippy, which exhibites the visage of typical freshwater ostracod.Four ichnofabric were identified, which are Scoyenia ichnofabric, Skolithos ichnofabric, Palaeophycus ichnofabric and acute disturb ichnofabric respectively.Based on the above research, five biofacies and ichnofacies were carved up, which represent overflow plain, small lake in the overflow plain, interchannel or subaqueous spreader interchannel, shallow lake and predelta sedimentary environments respectively.
2009, 34(3): 419-427.
Abstract:
Quaternary sediments in Jianghan Plain, the first large-scale offloading basin of the Yangtze River after the forming of Three Gorges, reflect the characteristics of provenance through which the Yangtze River flows.The heavy mineral samples were collected from the sand layer in the drilling core, with the size fraction ranging from 0.125 mm to 0.063 mm.We find that there is an obvious mutation of the combination and quantitative characteristics of heavy minerals at the depth of 110 m, with the paleomagnetic age of 1.1 Ma, through series of analyses including the change of content, index ATi, index GZi and index ZTR.The combination of characteristic heavy minerals from the sediments above the depth of 110 m is in accordance with the modern Yangtze River.So we conclude that the Three Gorges was formed at around 1.1 Ma when the materials from the upper reaches of the Three Gorges has deposited at Jianghan basin as a result of the transfixion of the Yangtze River.
Quaternary sediments in Jianghan Plain, the first large-scale offloading basin of the Yangtze River after the forming of Three Gorges, reflect the characteristics of provenance through which the Yangtze River flows.The heavy mineral samples were collected from the sand layer in the drilling core, with the size fraction ranging from 0.125 mm to 0.063 mm.We find that there is an obvious mutation of the combination and quantitative characteristics of heavy minerals at the depth of 110 m, with the paleomagnetic age of 1.1 Ma, through series of analyses including the change of content, index ATi, index GZi and index ZTR.The combination of characteristic heavy minerals from the sediments above the depth of 110 m is in accordance with the modern Yangtze River.So we conclude that the Three Gorges was formed at around 1.1 Ma when the materials from the upper reaches of the Three Gorges has deposited at Jianghan basin as a result of the transfixion of the Yangtze River.
2009, 34(3): 428-434.
Abstract:
The unconformity is formed due to the tectonic movement and the eustatic sea level change.The unconformity structure is very important for the pool forming.If the weathered clay is thick enough, it can become good capping layer.The pores, fissures and their connecting systems in the sapropelic rock provide good migrating channel and accumulating place for oil.Studying the mineralogical and geochemical characteristics of unconformity structure is the basic of the structure division which is important for the exploration of unconformity oil traps.The unconformity includes three structure types: the structure with weathered clay and the sapropelic rock, the structure only with sapropelic rock and the structure which formed during interruption of sedimentation.The mineralogical and geochemical examination results of Yihezhuang uplift pre-Tertiary buried weathered crust and some typical weathered crusts with weathered clay and sapropelic rock are summed up and the mineralogical and geochemical characteristics of such unconformity structure are given in this paper.The primary minerals that are not resistible to weathering such as feldspar and mica decreased and the secondary clay minerals such as kaolinite and illite increased gradually.The Fe and Al elements are rich in the clay layer and the upper part of the sapropelic rock.The Ca and Na elements lost heavily.But the contents of K and Mg elements are complicated owing to the factors such as replacement of these two elements.
The unconformity is formed due to the tectonic movement and the eustatic sea level change.The unconformity structure is very important for the pool forming.If the weathered clay is thick enough, it can become good capping layer.The pores, fissures and their connecting systems in the sapropelic rock provide good migrating channel and accumulating place for oil.Studying the mineralogical and geochemical characteristics of unconformity structure is the basic of the structure division which is important for the exploration of unconformity oil traps.The unconformity includes three structure types: the structure with weathered clay and the sapropelic rock, the structure only with sapropelic rock and the structure which formed during interruption of sedimentation.The mineralogical and geochemical examination results of Yihezhuang uplift pre-Tertiary buried weathered crust and some typical weathered crusts with weathered clay and sapropelic rock are summed up and the mineralogical and geochemical characteristics of such unconformity structure are given in this paper.The primary minerals that are not resistible to weathering such as feldspar and mica decreased and the secondary clay minerals such as kaolinite and illite increased gradually.The Fe and Al elements are rich in the clay layer and the upper part of the sapropelic rock.The Ca and Na elements lost heavily.But the contents of K and Mg elements are complicated owing to the factors such as replacement of these two elements.
2009, 34(3): 435-447.
Abstract:
The evolution of the South China Sea is one of the worldwide hot research spots.In order to investigate its evolution progress of tectonics, we compared three sets of analogue modeling experiments.Modeling experiments suggest that the fault patterns and orientation change of the rift zone were strongly related to the thermal situation and rheological stratification of the lithosphere.Comparing the modeling results with the fault patterns on the conjugate continental margin, we conjectured that the slope area might have born relatively hotter and thinner lithosphere than shelf area from the beginning of rifting.Due to the stretching and mantle upwelling associated with the regional extension, the initial rheological stratification was changed and therefore the rifting pattern from shelf to slope.Affected by the ductile flow of lower crust and asthenosphere, the faults became flattened, especially close to the breakup area.In the experiments, breakup developed first at isolated points, which grew and coalesced to become a single spreading area.The conjugate boundaries were either all concave or all convex.When there was a rigid massif located at the divergent boundary, the northern and southern areas of the massif thinned rapidly and developed into two deep troughs, which may finally evolve into spreading centers.The shape of the massif controls the orientation and boundary shape of the spreading area.It's supposed that the crustal breakup may go in more viscous style, and the NW sub sea basin may develop along the northern trough of the Zhongsha-Xisha massif.
The evolution of the South China Sea is one of the worldwide hot research spots.In order to investigate its evolution progress of tectonics, we compared three sets of analogue modeling experiments.Modeling experiments suggest that the fault patterns and orientation change of the rift zone were strongly related to the thermal situation and rheological stratification of the lithosphere.Comparing the modeling results with the fault patterns on the conjugate continental margin, we conjectured that the slope area might have born relatively hotter and thinner lithosphere than shelf area from the beginning of rifting.Due to the stretching and mantle upwelling associated with the regional extension, the initial rheological stratification was changed and therefore the rifting pattern from shelf to slope.Affected by the ductile flow of lower crust and asthenosphere, the faults became flattened, especially close to the breakup area.In the experiments, breakup developed first at isolated points, which grew and coalesced to become a single spreading area.The conjugate boundaries were either all concave or all convex.When there was a rigid massif located at the divergent boundary, the northern and southern areas of the massif thinned rapidly and developed into two deep troughs, which may finally evolve into spreading centers.The shape of the massif controls the orientation and boundary shape of the spreading area.It's supposed that the crustal breakup may go in more viscous style, and the NW sub sea basin may develop along the northern trough of the Zhongsha-Xisha massif.
2009, 34(3): 448-456.
Abstract:
The paleoprovenance system analysis is critical in terms of present sedimentary basin analysis, sequence stratigraphy study, and petroleum exploration practice.In this paper, we present a preliminarily summary of applying the "five-in-one" method to study provenace system of the Dongying Formation in the Qikou depression.The so-called "five-in-one" method is a compositive analysis of light-heavy minerals, seismic progradational reflection structure features, paleogeomorphy and gully expansion features, skeleton sand body forms within the basin and the time-space expansion and matching rules analysis, and basin margin and the spatial expansion features analysis of large-scale incised valley developed in its internal sequence boundary.This method undoubtedly provides a reference for the researches of other basins within the same field.However, we know that provenace analysis of sedimentary basin is a complicated job.With the development of science and technology, and the increase of basin data obtained, it will apply on the field together with more effective methods and technologies.It will also further approach the real status of provenace system, and provide better service for petroleum exploration.
The paleoprovenance system analysis is critical in terms of present sedimentary basin analysis, sequence stratigraphy study, and petroleum exploration practice.In this paper, we present a preliminarily summary of applying the "five-in-one" method to study provenace system of the Dongying Formation in the Qikou depression.The so-called "five-in-one" method is a compositive analysis of light-heavy minerals, seismic progradational reflection structure features, paleogeomorphy and gully expansion features, skeleton sand body forms within the basin and the time-space expansion and matching rules analysis, and basin margin and the spatial expansion features analysis of large-scale incised valley developed in its internal sequence boundary.This method undoubtedly provides a reference for the researches of other basins within the same field.However, we know that provenace analysis of sedimentary basin is a complicated job.With the development of science and technology, and the increase of basin data obtained, it will apply on the field together with more effective methods and technologies.It will also further approach the real status of provenace system, and provide better service for petroleum exploration.
2009, 34(3): 457-470.
Abstract:
The deep overpressured system occurs in the Jurassic Formation of the central area of Junggar basin.This has been confirmed by drill stem tests (DSTs) and modular dynamic formation tests (MDTs) with 67 measured formation pressures from 26 wells which reveal excessive pressures ranging from 11 MPa to 57 MPa with the pressure coefficients of 1.24 to 2.07 at depths between 4 470 m and 6 160 m.The measured overpressured values are mostly in the sandstone layers of Jurassic formation, only a few in the bottom of the Cretaceous formation and one in the Lower Triassic formation.The measured values of porosity and permeability of the overpressured sandstone samples range from 3.20% to 16.00% and 0.02×10-3 μm2 to 14.40×10-3 μm2 respectively.This fluid overpressured zone over depths of 4 430-6 650 m is coincident with marked increase of the density of drilling mud, as well as the response of overpressured shales and sandstones to high sonic transit times and low resistivity values relative to their normal trends.The observed data suggest that the burial depth of the top of magnitude overpressured zone may not be smaller than 4 400 m with a formation temperature of about 104 ℃, and the tops in some drilling wells are to reach as deep as about 6 000 m with a formation temperature of about 140 ℃, and the depth of the top of the deep overpressured zone changes with the burial depth of the Jurassic formation.The values of vitrinite reflectance (Ro, %) in the deep overpressured zone of Jurassic formation range from about 0.7% to 1.3%, which suggests that the variations of depth distribution of the overpressured zone are controlled by the burial depth of mature source-rocks of the Jurassic formation.This study indicates that the main origin of abnormally high pressures in the full-compacted Jurassic formation is generation-related oil and gas of the kerogen from the coal-bearing source-rocks.The physical simulation experiments show that the effective stress of rock framework reduces due to high pore fluid pressure, which can directly lead to the decrease of velocity of acoustic wave through the shale and sandstone rocks.As a result, the higher interval transit times respond to overpressuring rather than higher porosities anomaly due to compaction disequilibrium.Under the temperature of the overpressured formations, the ionization constant of high-pressure liquid water (near-critical water) may be increased, which is likely to decrease formation resistivity.Further study on this phenomenon is expected to offer a reasonable explanation for the cause of low formation resistivity in the observed overpressured zone.
The deep overpressured system occurs in the Jurassic Formation of the central area of Junggar basin.This has been confirmed by drill stem tests (DSTs) and modular dynamic formation tests (MDTs) with 67 measured formation pressures from 26 wells which reveal excessive pressures ranging from 11 MPa to 57 MPa with the pressure coefficients of 1.24 to 2.07 at depths between 4 470 m and 6 160 m.The measured overpressured values are mostly in the sandstone layers of Jurassic formation, only a few in the bottom of the Cretaceous formation and one in the Lower Triassic formation.The measured values of porosity and permeability of the overpressured sandstone samples range from 3.20% to 16.00% and 0.02×10-3 μm2 to 14.40×10-3 μm2 respectively.This fluid overpressured zone over depths of 4 430-6 650 m is coincident with marked increase of the density of drilling mud, as well as the response of overpressured shales and sandstones to high sonic transit times and low resistivity values relative to their normal trends.The observed data suggest that the burial depth of the top of magnitude overpressured zone may not be smaller than 4 400 m with a formation temperature of about 104 ℃, and the tops in some drilling wells are to reach as deep as about 6 000 m with a formation temperature of about 140 ℃, and the depth of the top of the deep overpressured zone changes with the burial depth of the Jurassic formation.The values of vitrinite reflectance (Ro, %) in the deep overpressured zone of Jurassic formation range from about 0.7% to 1.3%, which suggests that the variations of depth distribution of the overpressured zone are controlled by the burial depth of mature source-rocks of the Jurassic formation.This study indicates that the main origin of abnormally high pressures in the full-compacted Jurassic formation is generation-related oil and gas of the kerogen from the coal-bearing source-rocks.The physical simulation experiments show that the effective stress of rock framework reduces due to high pore fluid pressure, which can directly lead to the decrease of velocity of acoustic wave through the shale and sandstone rocks.As a result, the higher interval transit times respond to overpressuring rather than higher porosities anomaly due to compaction disequilibrium.Under the temperature of the overpressured formations, the ionization constant of high-pressure liquid water (near-critical water) may be increased, which is likely to decrease formation resistivity.Further study on this phenomenon is expected to offer a reasonable explanation for the cause of low formation resistivity in the observed overpressured zone.
2009, 34(3): 471-476.
Abstract:
The stratigraphic trap formation by mass transport deposition (MTD) in the deepwater area is very important for the deepwater exploration and production.Based on the new seismic data acquired recently and classic sequence stratigraphy theory, we study the deepwater deposition characteristics of Huaguang depression, Qiongdongnan basin.The sedimentary features relates with MTD develop since Miocene, including channel complex developed in Miocene Sanya Formation, Pliocene deformation slide layer and Quaternary deepwater turbidite channels.The Miocene channel complex has typical shingle structure of high amplitude and low amplitude reflection; the Pliocene deformation slide layer has typical deformation feature of lower part and slide of upper part; the Quaternary deepwater turbidite channels have typical lateral migration and bifurcation.These sediment phenomena are related with the sediment supply from the Vietnam uplift.The channel complex in Sanya Formation could be the potential reservoir of the slope deepwater area, and the formation of deformation slide layer may be related with the gas hydrate.
The stratigraphic trap formation by mass transport deposition (MTD) in the deepwater area is very important for the deepwater exploration and production.Based on the new seismic data acquired recently and classic sequence stratigraphy theory, we study the deepwater deposition characteristics of Huaguang depression, Qiongdongnan basin.The sedimentary features relates with MTD develop since Miocene, including channel complex developed in Miocene Sanya Formation, Pliocene deformation slide layer and Quaternary deepwater turbidite channels.The Miocene channel complex has typical shingle structure of high amplitude and low amplitude reflection; the Pliocene deformation slide layer has typical deformation feature of lower part and slide of upper part; the Quaternary deepwater turbidite channels have typical lateral migration and bifurcation.These sediment phenomena are related with the sediment supply from the Vietnam uplift.The channel complex in Sanya Formation could be the potential reservoir of the slope deepwater area, and the formation of deformation slide layer may be related with the gas hydrate.
2009, 34(3): 477-485.
Abstract:
In this paper, we present a case study where we combine sequence stratigraphiy with seismic velocity study for a 3D seismic survey landing at the SN21 well area in Junggar Basin, China.The main trap in this area is subtle composite trap of structure and lithology.Our purpose is to provide essential maps for demonstrating well location by predicting reservoir's lateral distribution and its depth.Firstly, according to the principle of sequence stratigraphy and the correlation analysis of well logs and seismic data, we constructed high-resolution stratigraphic frameworks in this subtle-reservoir area.Each framework has its given geological meaning.The three main frameworks are CX0 (reflection of QSH top), CX3 (reflection of TTH top), and CX5 (reflection of TTH bottom).Secondly, by using ray tracing techniques, we merged these sequence stratigraphic frameworks with the seismic rms velocities, as well as controlled logging and geological constraints, to estimate seismic interval velocity model of these stratigraphic frameworks.Study results demonstrate that, within target strata (CX0-CX3), the south and southeastern sand distribution area shows high velocity values, while the north mudstone low velocity values.The magnitude of velocity reflects the sand content.Study results also prove that the seismic velocity and the seismic amplitude attribute corroborates each other in predicting sand distribution.Furthermore, the estimated final velocity model for time to depth conversion has few systemic and random errors, and the predicted structure maps with this velocity model turn out to be of relatively high precision and coincide with the subsequent drilling data.
In this paper, we present a case study where we combine sequence stratigraphiy with seismic velocity study for a 3D seismic survey landing at the SN21 well area in Junggar Basin, China.The main trap in this area is subtle composite trap of structure and lithology.Our purpose is to provide essential maps for demonstrating well location by predicting reservoir's lateral distribution and its depth.Firstly, according to the principle of sequence stratigraphy and the correlation analysis of well logs and seismic data, we constructed high-resolution stratigraphic frameworks in this subtle-reservoir area.Each framework has its given geological meaning.The three main frameworks are CX0 (reflection of QSH top), CX3 (reflection of TTH top), and CX5 (reflection of TTH bottom).Secondly, by using ray tracing techniques, we merged these sequence stratigraphic frameworks with the seismic rms velocities, as well as controlled logging and geological constraints, to estimate seismic interval velocity model of these stratigraphic frameworks.Study results demonstrate that, within target strata (CX0-CX3), the south and southeastern sand distribution area shows high velocity values, while the north mudstone low velocity values.The magnitude of velocity reflects the sand content.Study results also prove that the seismic velocity and the seismic amplitude attribute corroborates each other in predicting sand distribution.Furthermore, the estimated final velocity model for time to depth conversion has few systemic and random errors, and the predicted structure maps with this velocity model turn out to be of relatively high precision and coincide with the subsequent drilling data.
2009, 34(3): 486-492.
Abstract:
Lunnan hydrocarbon province has recently experienced intensive gas invasion since the Himalayan movement, and some of the oils in the Ordovician reservoir show characteristics of progressive fractionation by gas moving.Based on the framework of the components phase equilibrium, the process of gas washing can deplete the n-alkanes of the oil and produce the subsequent condensates.Geochemistry analysis shows that both the residual oil and the condensates indicate the phase fractionation characteristics on their light ends (C6-C8). Moreover, gas chromatogram data show that the altered oils are depleted of light n-alkanes. Through calculating the mass depletion of oil in n-alkanes relative to an unfractionated oil (Q), it determines that oils in the Ordovician reservoir experienced great alternation of gas washing, and the Q value decreases westward.However, oils in the Carboniferous and Triassic reservoir show no depletion of the n-alkanes.
Lunnan hydrocarbon province has recently experienced intensive gas invasion since the Himalayan movement, and some of the oils in the Ordovician reservoir show characteristics of progressive fractionation by gas moving.Based on the framework of the components phase equilibrium, the process of gas washing can deplete the n-alkanes of the oil and produce the subsequent condensates.Geochemistry analysis shows that both the residual oil and the condensates indicate the phase fractionation characteristics on their light ends (C6-C8). Moreover, gas chromatogram data show that the altered oils are depleted of light n-alkanes. Through calculating the mass depletion of oil in n-alkanes relative to an unfractionated oil (Q), it determines that oils in the Ordovician reservoir experienced great alternation of gas washing, and the Q value decreases westward.However, oils in the Carboniferous and Triassic reservoir show no depletion of the n-alkanes.
Tectonic Styles and Kinematic Characteristics of Negative Inversion Structure in Dongying Depression
2009, 34(3): 493-501.
Abstract:
The strong negative inversion structure in Mesozoic-Cenozoic is a prominent characteristic during the tectonic evolution of Dongying depression.In order to understand the significance of the negative inversion structure in the process of Mesozoic-Cenozoic basin formation in Dongying depression, this paper describes in detail the geometry styles of negative inversion structures in Dongying depression on the basis of the interpretation of the new high resolution 3D seismic profiles.And by utilizing the methods of calculating the fault activity velocity, negative inversion ratio, and displacement-distance curve, the authors quantitatively analyse the kinematic characteristics of the negative inversion structures in Dongying depression.The result indicates that in the Dongying depression, the extension basins developed in J3-K1 and Ek-Es4 stages were mainly controlled by the negative inversion of the thrust faults formed in Indo-Chinese epoch.The total negative inversion ratio is 3.367-8.3, and the ratio in J3-K1 stage is 1.388-3.904.The negative inversion structures accomplished ultimately in the Es3-Es2 stage.The distribution of the negative inversion ratios indicates an increase in deformational degree from SW to NE in the whole region.The research of negative inversion structures in Dongying depression has important theoretic and practical significance in the exploration of the deep hydrocarbon reservoirs.
The strong negative inversion structure in Mesozoic-Cenozoic is a prominent characteristic during the tectonic evolution of Dongying depression.In order to understand the significance of the negative inversion structure in the process of Mesozoic-Cenozoic basin formation in Dongying depression, this paper describes in detail the geometry styles of negative inversion structures in Dongying depression on the basis of the interpretation of the new high resolution 3D seismic profiles.And by utilizing the methods of calculating the fault activity velocity, negative inversion ratio, and displacement-distance curve, the authors quantitatively analyse the kinematic characteristics of the negative inversion structures in Dongying depression.The result indicates that in the Dongying depression, the extension basins developed in J3-K1 and Ek-Es4 stages were mainly controlled by the negative inversion of the thrust faults formed in Indo-Chinese epoch.The total negative inversion ratio is 3.367-8.3, and the ratio in J3-K1 stage is 1.388-3.904.The negative inversion structures accomplished ultimately in the Es3-Es2 stage.The distribution of the negative inversion ratios indicates an increase in deformational degree from SW to NE in the whole region.The research of negative inversion structures in Dongying depression has important theoretic and practical significance in the exploration of the deep hydrocarbon reservoirs.
2009, 34(3): 502-510.
Abstract:
It is very significant to probe the complex charging history in Chaluhe depression of Yitong basin.1D numeric modelling of hydrocarbon generation and expulsion history of source rocks in 4 wells confirms that the major source rocks had entered their threshold of maturity at the Middle-Late Eocene and reached the peak generation stage at the Early-Middle Oligocene.For this study, 145 fluid inclusion samples from 19 wells have been employed to systematically obtain information on fluorescent colors of hydrocarbon inclusions, homogenization temperatures of oil inclusions and their coeval aqueous inclusions.The results indicate three events of oil charging for the Paleocene reservoirs.By integrating with the burial historical curves, the oil charging events have been reconstructed at 38.1-27 Ma, 19.5-10 Ma and 1-0 Ma respectively.When combining the known information on hydrocarbon charging history and structural evolution, two intermittent periods of hydrocarbon migration and accumulation have been revealed, which were at 27-19.6 Ma and 10-2 Ma, respectively, corresponding to two structural uplift stages.In other words, tectonic uplift events occurring at the Late Palaeogene and the Early Neogene stopped the hydrocarbon supplies or destroyed the migrated and accumulated hydrocarbon so that hydrocarbon inclusions can not be probed at the two stages.Therefore, the Late Eocene to Middle Oligocene, Early-Middle Miocene and the Quaternary are the three important reservoir-forming periods in Chaluhe fault depression.
It is very significant to probe the complex charging history in Chaluhe depression of Yitong basin.1D numeric modelling of hydrocarbon generation and expulsion history of source rocks in 4 wells confirms that the major source rocks had entered their threshold of maturity at the Middle-Late Eocene and reached the peak generation stage at the Early-Middle Oligocene.For this study, 145 fluid inclusion samples from 19 wells have been employed to systematically obtain information on fluorescent colors of hydrocarbon inclusions, homogenization temperatures of oil inclusions and their coeval aqueous inclusions.The results indicate three events of oil charging for the Paleocene reservoirs.By integrating with the burial historical curves, the oil charging events have been reconstructed at 38.1-27 Ma, 19.5-10 Ma and 1-0 Ma respectively.When combining the known information on hydrocarbon charging history and structural evolution, two intermittent periods of hydrocarbon migration and accumulation have been revealed, which were at 27-19.6 Ma and 10-2 Ma, respectively, corresponding to two structural uplift stages.In other words, tectonic uplift events occurring at the Late Palaeogene and the Early Neogene stopped the hydrocarbon supplies or destroyed the migrated and accumulated hydrocarbon so that hydrocarbon inclusions can not be probed at the two stages.Therefore, the Late Eocene to Middle Oligocene, Early-Middle Miocene and the Quaternary are the three important reservoir-forming periods in Chaluhe fault depression.
2009, 34(3): 511-524.
Abstract:
Geological field work in Tibet is rather tough and some information is unavailable for metallogenic prediction.Based on the former research achievements and the principle that highlights systematic, relevant, consistent in terms of target, integrated in criteria and contrasted in complexity and high accuracy, a new location prediction theory—"Xieyou" metallogenic prediction method, for areas with very bad conditions in West China is proposed, which is a "rapid approach to the prospecting target".This theory holds that only by selecting the combination of several key pieces of information which are relevant to each other, have a consistent target and reflect some characteristics of the special deposit, can we find such special deposit.The key point is that great stress should be laid on the leading function of the direct information and the implication of some relevant information, so as to highlight the coincidence between information and the prediction target, with which uncertainty and multi-solutions of information can be decreased and the prospecting risks can be reduced.This theory tries to discuss the metallogenic prediction from another aspect in prospecting field, which is practised in the areas with very bad conditions in West China.Lots of ore deposits were found in Gangdese, north Himalaya and Nyainqentanglha metallogenic belts by applying this method, which may accelerate the ore prospecting process and improve prospecting method in Gangdese area, or even in all the west areas of China.
Geological field work in Tibet is rather tough and some information is unavailable for metallogenic prediction.Based on the former research achievements and the principle that highlights systematic, relevant, consistent in terms of target, integrated in criteria and contrasted in complexity and high accuracy, a new location prediction theory—"Xieyou" metallogenic prediction method, for areas with very bad conditions in West China is proposed, which is a "rapid approach to the prospecting target".This theory holds that only by selecting the combination of several key pieces of information which are relevant to each other, have a consistent target and reflect some characteristics of the special deposit, can we find such special deposit.The key point is that great stress should be laid on the leading function of the direct information and the implication of some relevant information, so as to highlight the coincidence between information and the prediction target, with which uncertainty and multi-solutions of information can be decreased and the prospecting risks can be reduced.This theory tries to discuss the metallogenic prediction from another aspect in prospecting field, which is practised in the areas with very bad conditions in West China.Lots of ore deposits were found in Gangdese, north Himalaya and Nyainqentanglha metallogenic belts by applying this method, which may accelerate the ore prospecting process and improve prospecting method in Gangdese area, or even in all the west areas of China.
2009, 34(3): 525-532.
Abstract:
Aiming at the complex issue of system evolution in softening process of saturated red-bed soft rocks, the research on softening characteristics of soft rocks is carried out from the aspects of systemic openness, far-from equilibrium behavior and internal nonlinear mechanism to affirm the occurrence of dissipative structure in softening process.On this basis, dissipative structure theory is adopted to systematically analyze the formation mechanism of dissipative structure in softening process of saturated soft rocks.The result shows that softening process contains three stages: Near-equilibrium state, far-from-equilibrium self-organizing state and far-from-equilibrium critical state, and ultimately, the way of non-equilibrium phase transition leads to the generation of soft rock dissipative structure.Finally, based on the evolution law of structure fractal dimension, a bifurcation evolution model is preliminarily established to describe the formation process of soft rock dissipative structure.The result of applying this model to analyze the critical bifurcation phenomena occurring in softening tests of saturated soft rocks indicates that this soft rock dissipative structure is formed after experiencing the process of period-doubling bifurcation and destabilization for many times, and the times of three months and six months present obvious critical characteristics which are two breakthrough points for further study on dissipative dynamic softening process of soft rocks in future.
Aiming at the complex issue of system evolution in softening process of saturated red-bed soft rocks, the research on softening characteristics of soft rocks is carried out from the aspects of systemic openness, far-from equilibrium behavior and internal nonlinear mechanism to affirm the occurrence of dissipative structure in softening process.On this basis, dissipative structure theory is adopted to systematically analyze the formation mechanism of dissipative structure in softening process of saturated soft rocks.The result shows that softening process contains three stages: Near-equilibrium state, far-from-equilibrium self-organizing state and far-from-equilibrium critical state, and ultimately, the way of non-equilibrium phase transition leads to the generation of soft rock dissipative structure.Finally, based on the evolution law of structure fractal dimension, a bifurcation evolution model is preliminarily established to describe the formation process of soft rock dissipative structure.The result of applying this model to analyze the critical bifurcation phenomena occurring in softening tests of saturated soft rocks indicates that this soft rock dissipative structure is formed after experiencing the process of period-doubling bifurcation and destabilization for many times, and the times of three months and six months present obvious critical characteristics which are two breakthrough points for further study on dissipative dynamic softening process of soft rocks in future.
2009, 34(3): 533-538.
Abstract:
Endoglucanase, exoglucanase and cellobiase activities of ten cellulose degradation isolates from piggery sludge and manure were analyzed.A complex microbial system was constructed by five bacteria named as LCB03, LCB12, LCB52, LCD12 and LCD51 respectively with different cellobiase activities from these isolates.Tested from the perspective of physiology and microchemistry as well as molecular level, these five bacteria were identified as Pseudomonas citronellolis, Stenotrophomonas maltophilia, Pseudomonas aeruginosa, Pseudomonas aeruginosa and Flavobacterium mizutaii, respectively.So far, there are few papers on cellulose degradation using S.maltophilia and F.mizutaii.Each of the five bacteria could produce different types of cellobiase that co-catalyze degrading natural cellulose effectively, and the microbial system therefore has great potential in cellulose-related pollution control and waste utilization.
Endoglucanase, exoglucanase and cellobiase activities of ten cellulose degradation isolates from piggery sludge and manure were analyzed.A complex microbial system was constructed by five bacteria named as LCB03, LCB12, LCB52, LCD12 and LCD51 respectively with different cellobiase activities from these isolates.Tested from the perspective of physiology and microchemistry as well as molecular level, these five bacteria were identified as Pseudomonas citronellolis, Stenotrophomonas maltophilia, Pseudomonas aeruginosa, Pseudomonas aeruginosa and Flavobacterium mizutaii, respectively.So far, there are few papers on cellulose degradation using S.maltophilia and F.mizutaii.Each of the five bacteria could produce different types of cellobiase that co-catalyze degrading natural cellulose effectively, and the microbial system therefore has great potential in cellulose-related pollution control and waste utilization.
2009, 34(3): 540-546.
Abstract:
The sharing of distributed heterogeneous multi-source spatial data and the function sharing and cooperative devetopment among different manufacturers are tough problems in the domain of the current GIS application and development. We present a datacenter framework model for integration development, based on which the next generation GIS architecture and development model is proposed. In addition, we introduce the core technologies of datacenter-data warehouse technology, function warehouse technology, architecture and configuration technology, etc. Examples of applying the above technologies by the National Land and Resource Datacenter are presented, which provides a new solution for the implementation of large-scale information systems.
The sharing of distributed heterogeneous multi-source spatial data and the function sharing and cooperative devetopment among different manufacturers are tough problems in the domain of the current GIS application and development. We present a datacenter framework model for integration development, based on which the next generation GIS architecture and development model is proposed. In addition, we introduce the core technologies of datacenter-data warehouse technology, function warehouse technology, architecture and configuration technology, etc. Examples of applying the above technologies by the National Land and Resource Datacenter are presented, which provides a new solution for the implementation of large-scale information systems.
