2023 Vol. 48, No. 6
Display Method:
2023, 48(6): 2039-2066.
doi: 10.3799/dqkx.2023.094
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Abstract:
On the basis of review of strike-slip fault research history, formation mechanism and principal structural characteristics, the relationship between strike-slip fault in intraplate cratonic basins and hydrocarbon accumulation in China are emphatically discussed in this paper, which can be outlined as follows.(1) Strike-slip fault stress, growth mechanism and structural style determine the strike-slip fault belt having five features of "different systems in planar, segmentation in strike, zoning in lateral, layering in vertical, and differentiation within layers". (2) The relationship between strike-slip faults within intraplate and hydrocarbon accumulation indicates that the strike-slip fault plays six roles of "controlling source, transmission, reservoir enhancement, trap-forming, reservoiring, and hydrocarbon enrichment". (3) The delineation of this strike-slip-controlled reservoir bodies can be conducted from outcrop measurement to log data depiction to 3D seismic data characterization in steps, and the key is fracture distribution acquirement and fracture density prediction. And (4) the studies of hydrocarbon sourcing, charging and dating for the exploration of strike-slip-controlled reservoirs in intraplate provides a strong tool in the deep and ultra-deep cratonic basins in china. In addition, the comments of published papers in this special issue have been made. The expectation of this issue is serving as a modest spur to promote hydrocarbon exploration to come forward with the valuable contributions in China in future.
On the basis of review of strike-slip fault research history, formation mechanism and principal structural characteristics, the relationship between strike-slip fault in intraplate cratonic basins and hydrocarbon accumulation in China are emphatically discussed in this paper, which can be outlined as follows.(1) Strike-slip fault stress, growth mechanism and structural style determine the strike-slip fault belt having five features of "different systems in planar, segmentation in strike, zoning in lateral, layering in vertical, and differentiation within layers". (2) The relationship between strike-slip faults within intraplate and hydrocarbon accumulation indicates that the strike-slip fault plays six roles of "controlling source, transmission, reservoir enhancement, trap-forming, reservoiring, and hydrocarbon enrichment". (3) The delineation of this strike-slip-controlled reservoir bodies can be conducted from outcrop measurement to log data depiction to 3D seismic data characterization in steps, and the key is fracture distribution acquirement and fracture density prediction. And (4) the studies of hydrocarbon sourcing, charging and dating for the exploration of strike-slip-controlled reservoirs in intraplate provides a strong tool in the deep and ultra-deep cratonic basins in china. In addition, the comments of published papers in this special issue have been made. The expectation of this issue is serving as a modest spur to promote hydrocarbon exploration to come forward with the valuable contributions in China in future.
2023, 48(6): 2067-2086.
doi: 10.3799/dqkx.2023.037
Abstract:
Intraplate small-displacement strike-slip faults are widely developed and play an important role in controlling hydrocarbon migration and accumulation in sedimentary basins. It compares geometric characteristics of small-displacement strike-slip faults in Tarim, Sichuan, and Ordos basins in western and central China and shows the similarities and differences in structural style. It also discusses the geological setting that controls the small-scale faults evolution in these craton basins. The comparison shows that Tarim, Sichuan, and Ordos basins have four aspects of characteristics. (1) Intraplate small-displacement strike-slip faults are developed in the central and northern parts of Tarim basin, in the central part of Sichuan basin, and in the southern and northern Hangjinqi parts of Ordos basin. (2) The strike-slip faults in these three major basins show obvious linear features, but their location in each basin varies. The central and northern parts of the Tarim basin can be divided into five strike-slip fault development areas with different characteristics. The strike-slip faults in central part of Sichuan basin are irregular network, and the strike-slip faults in Jinghe area of Ordos basin are mainly NEE- trending and partially NW-trending. (3) The strike-slip fault in these three basins show high dips. In Tarim basin, fault geometries in cross-section include linear, positive flower and negative flower structures that developed in pure strike-slip, transtension, transpression and superposition or inversion. The strike-slip faults in the central Sichuan basin are mostly upright with few flower structures. The strike-slip faults in Jinghe area of Ordos basin have the characteristic of composite flower structure or "flower on flower" because of strike-slip inversion or reactivation.
Intraplate small-displacement strike-slip faults are widely developed and play an important role in controlling hydrocarbon migration and accumulation in sedimentary basins. It compares geometric characteristics of small-displacement strike-slip faults in Tarim, Sichuan, and Ordos basins in western and central China and shows the similarities and differences in structural style. It also discusses the geological setting that controls the small-scale faults evolution in these craton basins. The comparison shows that Tarim, Sichuan, and Ordos basins have four aspects of characteristics. (1) Intraplate small-displacement strike-slip faults are developed in the central and northern parts of Tarim basin, in the central part of Sichuan basin, and in the southern and northern Hangjinqi parts of Ordos basin. (2) The strike-slip faults in these three major basins show obvious linear features, but their location in each basin varies. The central and northern parts of the Tarim basin can be divided into five strike-slip fault development areas with different characteristics. The strike-slip faults in central part of Sichuan basin are irregular network, and the strike-slip faults in Jinghe area of Ordos basin are mainly NEE- trending and partially NW-trending. (3) The strike-slip fault in these three basins show high dips. In Tarim basin, fault geometries in cross-section include linear, positive flower and negative flower structures that developed in pure strike-slip, transtension, transpression and superposition or inversion. The strike-slip faults in the central Sichuan basin are mostly upright with few flower structures. The strike-slip faults in Jinghe area of Ordos basin have the characteristic of composite flower structure or "flower on flower" because of strike-slip inversion or reactivation.
2023, 48(6): 2087-2103.
doi: 10.3799/dqkx.2022.504
Abstract:
A series of NE-trending faults have been developed in the Yubei area of the Tarim basin and oil and gas were discovered. The structural styles of different segments of the fault zone are significantly different. In this paper, the Luoxi fault is taken as an example, the evolution and formation mechanism of the Luoxi thrust-strike-slip composite structure are discussed by means of sand box physical simulation and strain analysis, combined with the study of fault segmentation and active stages. The results show that Luoxi fault is a typical thrus-strike-slip composite strcture, and the plane of the Luoxi fault has a "three-segment" growth pattern, with uplift as a whole and sag as a local phenomenon. Based on the unconformity characteristics, depth-amplitude curves and chronostratigraphic framework, it is considered that the Luoxi fault experienced three stages of deformation: (1) the Middle Caledonian stage Ⅲ was the formative period of the rudiment of the Luoxi fault, and the thrust fault begins to rise weakly; (2) the late Gariton Luoxi fault is the main active stage, and the active intensity is stronger than the stage Ⅲ of Middle Caledonian; (3) the Early Hercynian period is the main period of strike slip reformation of Luoxi fault. The sandbox physical simulation experiment confirmed that the "three stages and two directions" superimposed deformation controlled the evolution and formation mechanism of the Luoxi fault, and the Middle Caledonian Ⅲ episode and the Late Caledonian stage controlled the formation of the oblique thrust uplift belt, the formation and evolution of "sag" was controlled by the early transtensional deformation at the Early Hercynian period. Strain analysis indicates that the favorable reservoir positions of the thrust-strike-slip composite structure are mainly concentrated in the boundary fault, strike-slip fault with small angle oblique intersection with the boundary fault and the fault confluence area, this is of great significance to the exploration of Tarim basin carbonate reservoirs controlled by thrust-strike-slip faults and large-scale reservoirs.
A series of NE-trending faults have been developed in the Yubei area of the Tarim basin and oil and gas were discovered. The structural styles of different segments of the fault zone are significantly different. In this paper, the Luoxi fault is taken as an example, the evolution and formation mechanism of the Luoxi thrust-strike-slip composite structure are discussed by means of sand box physical simulation and strain analysis, combined with the study of fault segmentation and active stages. The results show that Luoxi fault is a typical thrus-strike-slip composite strcture, and the plane of the Luoxi fault has a "three-segment" growth pattern, with uplift as a whole and sag as a local phenomenon. Based on the unconformity characteristics, depth-amplitude curves and chronostratigraphic framework, it is considered that the Luoxi fault experienced three stages of deformation: (1) the Middle Caledonian stage Ⅲ was the formative period of the rudiment of the Luoxi fault, and the thrust fault begins to rise weakly; (2) the late Gariton Luoxi fault is the main active stage, and the active intensity is stronger than the stage Ⅲ of Middle Caledonian; (3) the Early Hercynian period is the main period of strike slip reformation of Luoxi fault. The sandbox physical simulation experiment confirmed that the "three stages and two directions" superimposed deformation controlled the evolution and formation mechanism of the Luoxi fault, and the Middle Caledonian Ⅲ episode and the Late Caledonian stage controlled the formation of the oblique thrust uplift belt, the formation and evolution of "sag" was controlled by the early transtensional deformation at the Early Hercynian period. Strain analysis indicates that the favorable reservoir positions of the thrust-strike-slip composite structure are mainly concentrated in the boundary fault, strike-slip fault with small angle oblique intersection with the boundary fault and the fault confluence area, this is of great significance to the exploration of Tarim basin carbonate reservoirs controlled by thrust-strike-slip faults and large-scale reservoirs.
2023, 48(6): 2104-2116.
doi: 10.3799/dqkx.2022.475
Abstract:
Shunbei No. 5 strike-slip fault is a small-scale strike-slip fault zone in Shunbei and its surroundings of Tarim basin, which can be divided into three section: north, middle and south. In this paper, the northern segment of Shunbei No. 5 fault is selected as the research object, and the deformation characteristics and formation mechanism of the strike-slip fault are clarified by using the structural physical simulation experiment. The results show that the main features of the northern segment of Shunbei No. 5 fault are multi-segment, and three types of structural styles are developed, i.e., translational strike-slip type, compression-uplift type and pull-apart type. The main active period of the north segment is the Middle Caledonian stage Ⅲ and the Late Caledonian stage, which is characterized by two stages of metasomatic superimposed deformation, and the early stage (T74 interface) is characterized by the segment growth of various combinations, the late stage (T70 interface) shows the distribution characteristics of echelon normal faults. Based on the sandbox physical simulation of the north segment of Shunbei No. 5 fault, it is confirmed that the early strike-slip action controls the deformation characteristics of the fault segments, and the late transtensional action controls the distribution law of the echelon-type fault. Therefore, the "different period-different direction" superimposed deformation controls the deformation process and formation mechanism of strike-slip fault in the northern segment of Shunbei No. 5 fault.
Shunbei No. 5 strike-slip fault is a small-scale strike-slip fault zone in Shunbei and its surroundings of Tarim basin, which can be divided into three section: north, middle and south. In this paper, the northern segment of Shunbei No. 5 fault is selected as the research object, and the deformation characteristics and formation mechanism of the strike-slip fault are clarified by using the structural physical simulation experiment. The results show that the main features of the northern segment of Shunbei No. 5 fault are multi-segment, and three types of structural styles are developed, i.e., translational strike-slip type, compression-uplift type and pull-apart type. The main active period of the north segment is the Middle Caledonian stage Ⅲ and the Late Caledonian stage, which is characterized by two stages of metasomatic superimposed deformation, and the early stage (T74 interface) is characterized by the segment growth of various combinations, the late stage (T70 interface) shows the distribution characteristics of echelon normal faults. Based on the sandbox physical simulation of the north segment of Shunbei No. 5 fault, it is confirmed that the early strike-slip action controls the deformation characteristics of the fault segments, and the late transtensional action controls the distribution law of the echelon-type fault. Therefore, the "different period-different direction" superimposed deformation controls the deformation process and formation mechanism of strike-slip fault in the northern segment of Shunbei No. 5 fault.
2023, 48(6): 2117-2135.
doi: 10.3799/dqkx.2023.012
Abstract:
The northern and central segments of the Shunbei No.5 strike-slip fault zone are characterized by multi-stage superimposing deformation along with the strike and vertical. Because of the complex structural deformation, it is challenging to understand the deformation and then reconstruct its spatio-temporal evolution process. Based on high-precision 3D seismic data, through precise structural interpretation and analysis of seismic profiles, as well as structural back-stripping restoration, in this study it conducted a more comprehensive study on the structural deformation and multi-stage evolution process of the fault zone, the conclusions are as follows. (1) In the deep sections (Sinian to Middle Ordovician), the principle deformation zone of the fault is characterized by stress-strain localization along with the strike and in the vertical. (2) In the upper sections (Upper Ordovician to Carboniferous), there are transpressional folds and three sets of en echelon normal faults. The three sets of en echelon normal faults are superimposed vertically and formed in different periods. Among them, the No.1 and No.2 en echelon normal faults formed simultaneously with the transpressional anticlines. (3) In general, the northern and central segments of the Shunbei No. 5 strike-slip fault zone had experienced five stages of structural evolution processes, they are the initial rupture period (in phase I of the middle Caledonian), structural embryonic period (the deposition period of the Sangtamu Formation), intense structural deformation period (the deposition period of the Kepingtage Formation), structural inheritance period (from the end of the Early Silurian to the Middle Devonian), and structural inversion period (in Permian).
The northern and central segments of the Shunbei No.5 strike-slip fault zone are characterized by multi-stage superimposing deformation along with the strike and vertical. Because of the complex structural deformation, it is challenging to understand the deformation and then reconstruct its spatio-temporal evolution process. Based on high-precision 3D seismic data, through precise structural interpretation and analysis of seismic profiles, as well as structural back-stripping restoration, in this study it conducted a more comprehensive study on the structural deformation and multi-stage evolution process of the fault zone, the conclusions are as follows. (1) In the deep sections (Sinian to Middle Ordovician), the principle deformation zone of the fault is characterized by stress-strain localization along with the strike and in the vertical. (2) In the upper sections (Upper Ordovician to Carboniferous), there are transpressional folds and three sets of en echelon normal faults. The three sets of en echelon normal faults are superimposed vertically and formed in different periods. Among them, the No.1 and No.2 en echelon normal faults formed simultaneously with the transpressional anticlines. (3) In general, the northern and central segments of the Shunbei No. 5 strike-slip fault zone had experienced five stages of structural evolution processes, they are the initial rupture period (in phase I of the middle Caledonian), structural embryonic period (the deposition period of the Sangtamu Formation), intense structural deformation period (the deposition period of the Kepingtage Formation), structural inheritance period (from the end of the Early Silurian to the Middle Devonian), and structural inversion period (in Permian).
2023, 48(6): 2136-2150.
doi: 10.3799/dqkx.2022.495
Abstract:
With the acquisition of high-precision continuous 3D seismic data, the intracratonic strike-slip faults with medium to small slip displacements reveal complex spatial structure and structural style. In this study it carries out detailed analysis on the three-dimensional spatial structure, kinematic characteristics and movement periods of the Shunbei No. 12 fault and its formation mechanism. The results show follows: (1) The compressional deformation of the first-order strike-slip faults in the Shunbei area gradually increases from the west to the east. Among these strike-slip faults, the Shunbei No. 12 fault is located in a transitional position in the NE-trending strike-slip fault system. In terms of structural style, both the "pull-up structure, strike-slip segment, and push-up structure" segmented structure and the "pressure ridge structure" of the faults to the west and to the east, respectively, are developed. (2) In the north of the carbonate rock top surface of Shunbei No. 12 fault, NE 20° trending branch faults are developed. The upper en echelon normal faults are strongly active, forming a fan-shaped geometry. The lower fault is characterized by steeply dipping faults, forming into a new structural style. (3) Under the influence of tectonic events at the plate boundaries, the Shunbei No. 12 fault and its derived branches experienced three stages of left lateral strike slip movements: in the third episode of the Middle Caledonian period, the Shunbei No. 12 fault and the branch faults were initiated. In the Late Caledonian period, multiple fault planes were activated and interacted with each other, dragging the overlying strata to form the first series of en echelon normal fault. In the Middle Hercynian period, the second series of en echelon normal faults were formed.
With the acquisition of high-precision continuous 3D seismic data, the intracratonic strike-slip faults with medium to small slip displacements reveal complex spatial structure and structural style. In this study it carries out detailed analysis on the three-dimensional spatial structure, kinematic characteristics and movement periods of the Shunbei No. 12 fault and its formation mechanism. The results show follows: (1) The compressional deformation of the first-order strike-slip faults in the Shunbei area gradually increases from the west to the east. Among these strike-slip faults, the Shunbei No. 12 fault is located in a transitional position in the NE-trending strike-slip fault system. In terms of structural style, both the "pull-up structure, strike-slip segment, and push-up structure" segmented structure and the "pressure ridge structure" of the faults to the west and to the east, respectively, are developed. (2) In the north of the carbonate rock top surface of Shunbei No. 12 fault, NE 20° trending branch faults are developed. The upper en echelon normal faults are strongly active, forming a fan-shaped geometry. The lower fault is characterized by steeply dipping faults, forming into a new structural style. (3) Under the influence of tectonic events at the plate boundaries, the Shunbei No. 12 fault and its derived branches experienced three stages of left lateral strike slip movements: in the third episode of the Middle Caledonian period, the Shunbei No. 12 fault and the branch faults were initiated. In the Late Caledonian period, multiple fault planes were activated and interacted with each other, dragging the overlying strata to form the first series of en echelon normal fault. In the Middle Hercynian period, the second series of en echelon normal faults were formed.
2023, 48(6): 2151-2167.
doi: 10.3799/dqkx.2023.065
Abstract:
In order to deepen the understanding of geometric characteristics and genetic mechanism of strike-slip faults with small displacement in Tarim basin, the characteristics of the No. 18 strike-slip faults in Shunnan area in detail were studied. Using the latest 3D seismic data and well data, it discusses its genetic mechanism. The aspect ratio of the faults is about 1∶10, and the faults are the longest in the middle in vertical direction; the faults have features such as duplex structures, horsetail fans, left and right echelons on the map, and such as flower structural styles and graben on seismic profiles; the fault properties and throw are different, and the linkage of faults is soft-link, followed by hard-link; the segmentation characteristics of the faults in different structural layers have inheritance and difference, and there are great differences in the combination of longitudinal structural styles in different positions on the map. Affected by early faults, the deformability of different strata and the different strike-slip activities in different periods, the faults had preliminary formed in the late of the Early Cambrian. The faults experienced successively right and left-lateral strike-slip activities in the Late Ordovician, and the activities were the strongest on the middle of map and the flower structure was formed where the strata physics changes frequently in the Upper Ordovician; respectively the horsetail in the southern and strike-slip double structure in the northern were gradually formed during this period. The northern faults experienced intense left-lateral strike-slip activity between the Late Silurian and the Early Carboniferous, and it promoted the lateral hard-link of faults. The middle faults experienced weak right-lateral strike-slip activity during the Late Carboniferous, and it promoted the formation of flower structures. The echelons were formed in the clastic rock with poweless deformability.
In order to deepen the understanding of geometric characteristics and genetic mechanism of strike-slip faults with small displacement in Tarim basin, the characteristics of the No. 18 strike-slip faults in Shunnan area in detail were studied. Using the latest 3D seismic data and well data, it discusses its genetic mechanism. The aspect ratio of the faults is about 1∶10, and the faults are the longest in the middle in vertical direction; the faults have features such as duplex structures, horsetail fans, left and right echelons on the map, and such as flower structural styles and graben on seismic profiles; the fault properties and throw are different, and the linkage of faults is soft-link, followed by hard-link; the segmentation characteristics of the faults in different structural layers have inheritance and difference, and there are great differences in the combination of longitudinal structural styles in different positions on the map. Affected by early faults, the deformability of different strata and the different strike-slip activities in different periods, the faults had preliminary formed in the late of the Early Cambrian. The faults experienced successively right and left-lateral strike-slip activities in the Late Ordovician, and the activities were the strongest on the middle of map and the flower structure was formed where the strata physics changes frequently in the Upper Ordovician; respectively the horsetail in the southern and strike-slip double structure in the northern were gradually formed during this period. The northern faults experienced intense left-lateral strike-slip activity between the Late Silurian and the Early Carboniferous, and it promoted the lateral hard-link of faults. The middle faults experienced weak right-lateral strike-slip activity during the Late Carboniferous, and it promoted the formation of flower structures. The echelons were formed in the clastic rock with poweless deformability.
2023, 48(6): 2168-2188.
doi: 10.3799/dqkx.2023.103
Abstract:
Significant physical and chemical differences of crude oil properties in strike-slip faulted karst Ordovician reservoirs occur both among the strike-slip faulted belts and the different segments of the same strike-slip faulted belt in Shunbei area, Tarim basin. It is, therefore, very important to reveal the processes of resulting in the physical and chemical heterogeneity of crude oils for hydrocarbon exploration and development in this area. In this study, 100 core samples from 17 wells have been taken to make systematic fluid inclusion measurement. On the basis of determinations of hydrocarbon charging events and chronologies of hydrocarbon migration and accumulation, a bridging relationship between crude oil APIo calculated by crude oil densities and the microspectrofluorimetric QF-535 parameter of individual oil inclusions has been used to obtain the APIo statistical distribution models of single oil inclusions, which can be used for quantitative assessment of contribution percentages (CP) of each oil charging events. Comparing the physical and chemical properties of crude oils (density, viscosity, gas/oil ratio and Ro-MPI1) and the microspectrofluorimetric parameters (QF-535, λmax and CP) of each charging events, some research conclusions are archived as followings. (1) Total four oil charging events happened in the strike-slip faulted karst reservoirs in Shunbei area, which is consisted of the Late Caledonian (438.2-405.8 Ma), the Late Hercynian (297.8-219.5 Ma), the Middle and Late Yanshanian (139.9-106.1 Ma), and the Middle and Late Himalayan (29.0-0.3 Ma). (2) The changing tendency of crude oil properties, both from the west to the east, and the north to the south, shows declining of density and viscosity, and ascending of gas/oil ratio and oil maturity (Ro-MPI1), which may be the result of the contribution percentages increasing of the late oil charging events (e.g. the third and fourth charging events) and natural gas invasion modification both at the two same directions.
Significant physical and chemical differences of crude oil properties in strike-slip faulted karst Ordovician reservoirs occur both among the strike-slip faulted belts and the different segments of the same strike-slip faulted belt in Shunbei area, Tarim basin. It is, therefore, very important to reveal the processes of resulting in the physical and chemical heterogeneity of crude oils for hydrocarbon exploration and development in this area. In this study, 100 core samples from 17 wells have been taken to make systematic fluid inclusion measurement. On the basis of determinations of hydrocarbon charging events and chronologies of hydrocarbon migration and accumulation, a bridging relationship between crude oil APIo calculated by crude oil densities and the microspectrofluorimetric QF-535 parameter of individual oil inclusions has been used to obtain the APIo statistical distribution models of single oil inclusions, which can be used for quantitative assessment of contribution percentages (CP) of each oil charging events. Comparing the physical and chemical properties of crude oils (density, viscosity, gas/oil ratio and Ro-MPI1) and the microspectrofluorimetric parameters (QF-535, λmax and CP) of each charging events, some research conclusions are archived as followings. (1) Total four oil charging events happened in the strike-slip faulted karst reservoirs in Shunbei area, which is consisted of the Late Caledonian (438.2-405.8 Ma), the Late Hercynian (297.8-219.5 Ma), the Middle and Late Yanshanian (139.9-106.1 Ma), and the Middle and Late Himalayan (29.0-0.3 Ma). (2) The changing tendency of crude oil properties, both from the west to the east, and the north to the south, shows declining of density and viscosity, and ascending of gas/oil ratio and oil maturity (Ro-MPI1), which may be the result of the contribution percentages increasing of the late oil charging events (e.g. the third and fourth charging events) and natural gas invasion modification both at the two same directions.
2023, 48(6): 2189-2203.
doi: 10.3799/dqkx.2023.089
Abstract:
Multi-stage calcite veins and solid bitumen filled in the Middle and Lower Cambrian strike-slip fault zone of the field outcrops for Keping Area, northwest of Tarim basin, are important medium to reveal the fluid activity history and hydrocarbon accumulation process. Based on the observation of the filling and distribution characteristics of calcite veins and bitumen in outcrop of strike-slip fault zones, the paragenetic sequence of calcite veins and bitumen and the origin fluid properties were determined using the thin section observation, cathodoluminescence, in-situ trace and rare earth element testing, carbon and oxygen isotopes measurement, system analysis of fluid inclusion, and the evolution of paleo-fluid in the strike-slip fault zones of the Middle and Lower Cambrian and its coupling relationship with hydrocarbon charging process were investigated. The results show that there are at least five phases of calcite veins in the strike-slip fault zones of the Middle and Lower Cambrian for Keping area of Xinjiang, C1, C2, C3, C4 and C5 respectively. The C1 calcite vein-forming fluid was mainly derived from formation water of the local layer and partly mixed with the brine of the Awatage Formation that infiltrated along the strike-slip fault. The C2 and C3 calcite vein-forming fluids were mainly the mixture of formation water and hydrocarbon-bearing hydrothermal fluids, but the formation temperature of C3 was slightly lower. The C4 calcite vein-forming fluid was mainly formation water, and there was mixing of atmospheric fresh water. The C5 calcite vein-forming fluid was mainly the mixture of formation water, hydrocarbon-bearing hydrothermal fluid and atmospheric fresh water. The formation stages of C1, C2, C3, C4 and C5 calcite veins were associated with tectonic activities of Keping area and generated in the Middle and Late Caledonian periods, Middle and Late Hercynian periods, Indosinian to Middle Yanshanian periods, Late Yanshanian and Himalayan periods, respectively. Three hydrocarbon charging phases were recognized, the Middle and Late Hercynian periods, Indosinian to Middle Yanshanian period and Himalayan period, respectively. The Middle and Late Hercynian periods and the Middle Inindo-Yanshanian period may be the main formation period of the primary oil and gas reservoirs for the Middle and Lower Cambrian in the Keping area, and the Himalayan period was an important period of oil and gas reservoir adjustment and hydrocarbon reaccumulation. The traps formed in Himalayan period and related to strike-slip faults also have favorable conditions for petroleum accumulation.
Multi-stage calcite veins and solid bitumen filled in the Middle and Lower Cambrian strike-slip fault zone of the field outcrops for Keping Area, northwest of Tarim basin, are important medium to reveal the fluid activity history and hydrocarbon accumulation process. Based on the observation of the filling and distribution characteristics of calcite veins and bitumen in outcrop of strike-slip fault zones, the paragenetic sequence of calcite veins and bitumen and the origin fluid properties were determined using the thin section observation, cathodoluminescence, in-situ trace and rare earth element testing, carbon and oxygen isotopes measurement, system analysis of fluid inclusion, and the evolution of paleo-fluid in the strike-slip fault zones of the Middle and Lower Cambrian and its coupling relationship with hydrocarbon charging process were investigated. The results show that there are at least five phases of calcite veins in the strike-slip fault zones of the Middle and Lower Cambrian for Keping area of Xinjiang, C1, C2, C3, C4 and C5 respectively. The C1 calcite vein-forming fluid was mainly derived from formation water of the local layer and partly mixed with the brine of the Awatage Formation that infiltrated along the strike-slip fault. The C2 and C3 calcite vein-forming fluids were mainly the mixture of formation water and hydrocarbon-bearing hydrothermal fluids, but the formation temperature of C3 was slightly lower. The C4 calcite vein-forming fluid was mainly formation water, and there was mixing of atmospheric fresh water. The C5 calcite vein-forming fluid was mainly the mixture of formation water, hydrocarbon-bearing hydrothermal fluid and atmospheric fresh water. The formation stages of C1, C2, C3, C4 and C5 calcite veins were associated with tectonic activities of Keping area and generated in the Middle and Late Caledonian periods, Middle and Late Hercynian periods, Indosinian to Middle Yanshanian periods, Late Yanshanian and Himalayan periods, respectively. Three hydrocarbon charging phases were recognized, the Middle and Late Hercynian periods, Indosinian to Middle Yanshanian period and Himalayan period, respectively. The Middle and Late Hercynian periods and the Middle Inindo-Yanshanian period may be the main formation period of the primary oil and gas reservoirs for the Middle and Lower Cambrian in the Keping area, and the Himalayan period was an important period of oil and gas reservoir adjustment and hydrocarbon reaccumulation. The traps formed in Himalayan period and related to strike-slip faults also have favorable conditions for petroleum accumulation.
2023, 48(6): 2204-2220.
doi: 10.3799/dqkx.2023.108
Abstract:
Fault identification of different scales in marine carbonate rock remains a big challenge for geophysicists. In this paper, aiming at identifying and interpreting fault distribution, especially the small strike-slip faults, it presents the implementation of seismic attributes with the information of fault structure and discontinuity change in mapping the fracture zone distribution in the Sinian-Paleozoic-Permian formation, Gaomo area, Sichuan basin. Technologies such as structural steering filtering, eigenvalue coherence, frequency division coherence and azimuth division coherence, maximum positive/negative curvature attribute, ant body attribute, maximum likelihood fracture identification and PADD (poststack amplitude direction decomposition) are used to describe the faults with different layers, azimuth and scale, which are forming in the types of seismic events dislocation, deflection, micro fault and karst collapse body. Also, the imaging logging is applied to verify the fracture orientation and fracture density of different scales qualitatively and show good coincidence with the results predicted with the seismic attribute. Based on the experiment, it summarizes "three classification and eight steps" gradually controlled fault identification techniques which can distinguish the strike-slip fault of different scales effectively and constructes six types of strike-slip fault structural styles in the central uplift of Sichuan basin.
Fault identification of different scales in marine carbonate rock remains a big challenge for geophysicists. In this paper, aiming at identifying and interpreting fault distribution, especially the small strike-slip faults, it presents the implementation of seismic attributes with the information of fault structure and discontinuity change in mapping the fracture zone distribution in the Sinian-Paleozoic-Permian formation, Gaomo area, Sichuan basin. Technologies such as structural steering filtering, eigenvalue coherence, frequency division coherence and azimuth division coherence, maximum positive/negative curvature attribute, ant body attribute, maximum likelihood fracture identification and PADD (poststack amplitude direction decomposition) are used to describe the faults with different layers, azimuth and scale, which are forming in the types of seismic events dislocation, deflection, micro fault and karst collapse body. Also, the imaging logging is applied to verify the fracture orientation and fracture density of different scales qualitatively and show good coincidence with the results predicted with the seismic attribute. Based on the experiment, it summarizes "three classification and eight steps" gradually controlled fault identification techniques which can distinguish the strike-slip fault of different scales effectively and constructes six types of strike-slip fault structural styles in the central uplift of Sichuan basin.
2023, 48(6): 2221-2237.
doi: 10.3799/dqkx.2022.478
Abstract:
In order to clarify the relationship between strike-slip faults and hydrocarbon accumulation of marine strata in the central and western Sichuan basin, based on a large area of 3D seismic data, fine interpretation of faults, isotopic dating of various filling minerals in fractures and caves, comprehensive analyses of discovered typical gas reservoirs, the development and distribution characteristics of the strike-slip faults, the main active period and the control effect on marine oil and gas accumulation are revealed, the natural gas accumulation models of the strike-slip fault zone is established, and the favorable exploration areas are pointed out. The strike-slip faults in the central and western Sichuan basin are characterized by layering and zoning development. The strata develop mainly in the Sinian-Paleozoic strata, and can be divided into three fault developed structural deformation layers; It is mainly distributed in the paleo uplift and anticline area in the middle of Sichuan, mainly in the near east-west fault, with good inheritance from deep to shallow fault; Ziyang Gaoshiti, Jianyang Moxi, Moxibei, Zhongjiang Shehong, Yanting Yingshan and Langzhong are identified as six near east-west main strike-slip fault zones. The dating results of the filling materials in the fractures and caves show that there are mainly three stages of strike-slip faults and fluid activities in Caledonian-Early Hercynian, Late Hercynian-Indosinian and middle Yanshanian-Himalayan. The effects of fault activities on oil and gas accumulation in different periods are different. The strike-slip fault connects multiple sets of source reservoir combinations of Sinian-Paleozoic, and has a significant control effect on the migration and accumulation of marine oil and gas and the three-dimensional reservoir formation of multi-layer system. It has been found that oil and gas fields and high-yield wells are mainly distributed near the strike-slip fault. Four differential three-dimensional reservoir forming models of strike-slip fracture zone are established, and seven favorable exploration areas are pointed out, which can provide basis for exploration deployment.
In order to clarify the relationship between strike-slip faults and hydrocarbon accumulation of marine strata in the central and western Sichuan basin, based on a large area of 3D seismic data, fine interpretation of faults, isotopic dating of various filling minerals in fractures and caves, comprehensive analyses of discovered typical gas reservoirs, the development and distribution characteristics of the strike-slip faults, the main active period and the control effect on marine oil and gas accumulation are revealed, the natural gas accumulation models of the strike-slip fault zone is established, and the favorable exploration areas are pointed out. The strike-slip faults in the central and western Sichuan basin are characterized by layering and zoning development. The strata develop mainly in the Sinian-Paleozoic strata, and can be divided into three fault developed structural deformation layers; It is mainly distributed in the paleo uplift and anticline area in the middle of Sichuan, mainly in the near east-west fault, with good inheritance from deep to shallow fault; Ziyang Gaoshiti, Jianyang Moxi, Moxibei, Zhongjiang Shehong, Yanting Yingshan and Langzhong are identified as six near east-west main strike-slip fault zones. The dating results of the filling materials in the fractures and caves show that there are mainly three stages of strike-slip faults and fluid activities in Caledonian-Early Hercynian, Late Hercynian-Indosinian and middle Yanshanian-Himalayan. The effects of fault activities on oil and gas accumulation in different periods are different. The strike-slip fault connects multiple sets of source reservoir combinations of Sinian-Paleozoic, and has a significant control effect on the migration and accumulation of marine oil and gas and the three-dimensional reservoir formation of multi-layer system. It has been found that oil and gas fields and high-yield wells are mainly distributed near the strike-slip fault. Four differential three-dimensional reservoir forming models of strike-slip fracture zone are established, and seven favorable exploration areas are pointed out, which can provide basis for exploration deployment.
2023, 48(6): 2238-2253.
doi: 10.3799/dqkx.2022.505
Abstract:
Multiple strike-slip faults have been identified in the Gaoshiti-Moxi area in the central Sichuan basin. In order to deepen the understanding of the structural geometry and kinematic characteristics of these strike-slip faults, based on deep drilling and high-precision three-dimensional seismic data in the central Sichuan basin, in this paper it describes in detail the structural geometry of the No.9 strike-slip fault zone in the Gaoshiti-Moxi area, and establishes a three-dimensional structural model of the fault. The formation and evolution process is reconstructed through structural back stripping and inversion. The No.9 strike-slip fault zone is nearly east-west trending, with an extension length of 60 km, showing a dextral transtensional fault. The fault zone develops horsetail structure, linear structure, oblique structure, and overlapping zones on the plane, with obvious segmentation characteristics. Typical strike-slip structural styles such as high-steep linear structure, 'Y'-shaped and anti-'Y'-shaped structures, flower structures are developed on the section. The different tectonic styles developed in different strata. The fault zone is composed of 7 main faults, and the development scale, inclination and connection mode of each fault slice are different. On the basis of pre-existing basement faults, the No.9 strike-slip fault zone experienced three stages of deformations: the embryonic development stage in the Late Sinian-Early Caledonian, the main growth stage in the Late Caledonian, and the inherited extension stage of Late Permian. The faults developed different growth patterns in Proterozoic-Lower Paleozoic: (1) the fault gradually grows upward from basement, and the fault throws of the upper and lower strata is consistent or gradually reduced; (2) the fault core is located in the Lower Paleozoic, the fault gradually propagated up and down during the active period, and the fault throw of the Lower Paleozoic strata was larger than that of the underlying strata.
Multiple strike-slip faults have been identified in the Gaoshiti-Moxi area in the central Sichuan basin. In order to deepen the understanding of the structural geometry and kinematic characteristics of these strike-slip faults, based on deep drilling and high-precision three-dimensional seismic data in the central Sichuan basin, in this paper it describes in detail the structural geometry of the No.9 strike-slip fault zone in the Gaoshiti-Moxi area, and establishes a three-dimensional structural model of the fault. The formation and evolution process is reconstructed through structural back stripping and inversion. The No.9 strike-slip fault zone is nearly east-west trending, with an extension length of 60 km, showing a dextral transtensional fault. The fault zone develops horsetail structure, linear structure, oblique structure, and overlapping zones on the plane, with obvious segmentation characteristics. Typical strike-slip structural styles such as high-steep linear structure, 'Y'-shaped and anti-'Y'-shaped structures, flower structures are developed on the section. The different tectonic styles developed in different strata. The fault zone is composed of 7 main faults, and the development scale, inclination and connection mode of each fault slice are different. On the basis of pre-existing basement faults, the No.9 strike-slip fault zone experienced three stages of deformations: the embryonic development stage in the Late Sinian-Early Caledonian, the main growth stage in the Late Caledonian, and the inherited extension stage of Late Permian. The faults developed different growth patterns in Proterozoic-Lower Paleozoic: (1) the fault gradually grows upward from basement, and the fault throws of the upper and lower strata is consistent or gradually reduced; (2) the fault core is located in the Lower Paleozoic, the fault gradually propagated up and down during the active period, and the fault throw of the Lower Paleozoic strata was larger than that of the underlying strata.
2023, 48(6): 2254-2266.
doi: 10.3799/dqkx.2023.018
Abstract:
Strike-slip faults play an important role in controlling hydrocarbon accumulation. In order to investigate the effect of strike-slip faults on the Sinian-Cambrian hydrocarbon accumulation in the Gaoshiti-Moxi area of Sichuan basin, seismic interpretation of strike-slip faults and systematic fluid inclusion analysis of diagenetic minerals filled in solution vugs were carried out, and the active stages of strike-slip faults and the hydrocarbon accumulation orders were determined. Moreover, the coupling relationship between strike-slip fault active stages and the hydrocarbon accumulation orders were discussed, and established a "floor type" hydrocarbon accumulation model controlled by strike-slip fault. Under this model, there are multiple sets of high-quality reservoirs developed vertically, which are shown as multi-layer systems containing oil and gas, and the oil and gas accumulation characteristics of each layer system are highly similar. For the areas where there is a "floor type" oil and gas accumulation mode, attention should be paid to three-dimensional exploration.
Strike-slip faults play an important role in controlling hydrocarbon accumulation. In order to investigate the effect of strike-slip faults on the Sinian-Cambrian hydrocarbon accumulation in the Gaoshiti-Moxi area of Sichuan basin, seismic interpretation of strike-slip faults and systematic fluid inclusion analysis of diagenetic minerals filled in solution vugs were carried out, and the active stages of strike-slip faults and the hydrocarbon accumulation orders were determined. Moreover, the coupling relationship between strike-slip fault active stages and the hydrocarbon accumulation orders were discussed, and established a "floor type" hydrocarbon accumulation model controlled by strike-slip fault. Under this model, there are multiple sets of high-quality reservoirs developed vertically, which are shown as multi-layer systems containing oil and gas, and the oil and gas accumulation characteristics of each layer system are highly similar. For the areas where there is a "floor type" oil and gas accumulation mode, attention should be paid to three-dimensional exploration.
2023, 48(6): 2267-2280.
doi: 10.3799/dqkx.2022.477
Abstract:
The intraplate strike-slip faults of the craton basin play an important role in controlling carbonate karst and reservoir formation. The faults in the main slope area of the Ordos basin are highly hidden, distributed in disorder, and difficult to analyze. At present, the research is weak, which restricts the recognition of basin tectonic evolution and multi-layer system three-dimensional reservoir formation. Guided by the structural analysis of oil area, the structural characteristics and tectonic evolution of strike-slip faults in the study area are configured and determined by using the fine interpretation of 3D seismic data of Daniudi block in Ordos basin. The study shows follows (1) there are four strike-slip faults with different strikes in Daniudi block, namely, the near NS-NNE trending Shibantai fault, the NW Tuweihe fault and the Xiaohaotu fault, and the NEE Taigemiao fault, which are characterized by vertical stratification and strike segmentation. (2) The formation and evolution of strike-slip faults in Daniudi block can be divided into four stages: Caledonian-Hercynian stage, Indosinian stage, Yanshanian stage and Himalayan stage. Among them, the right-step for left-lateral Taigemiao fault and the left-step for right-lateral northern Shibantai fault were formed from the Caledonian-Hercynian period to the Indosinian period; and the left-step for right-lateral Tuweihe fault and the right-step for left-lateral southern Shibantai fault were formed in the Yanshan period. (3)The formation background and mechanism of strike-slip faults in Daniudi block was affected by the interaction of surrounding plates. The X-type fault system composed of the northern Shibantai fault and Taigemiao fault is related to the collision and compression between the Yangtze plate and the North China craton, while the X-type fault system composed of the southern Shibantai fault and the Tuweihe fault is related to the subduction and compression of the ancient Pacific plate to the Eurasian plate.
The intraplate strike-slip faults of the craton basin play an important role in controlling carbonate karst and reservoir formation. The faults in the main slope area of the Ordos basin are highly hidden, distributed in disorder, and difficult to analyze. At present, the research is weak, which restricts the recognition of basin tectonic evolution and multi-layer system three-dimensional reservoir formation. Guided by the structural analysis of oil area, the structural characteristics and tectonic evolution of strike-slip faults in the study area are configured and determined by using the fine interpretation of 3D seismic data of Daniudi block in Ordos basin. The study shows follows (1) there are four strike-slip faults with different strikes in Daniudi block, namely, the near NS-NNE trending Shibantai fault, the NW Tuweihe fault and the Xiaohaotu fault, and the NEE Taigemiao fault, which are characterized by vertical stratification and strike segmentation. (2) The formation and evolution of strike-slip faults in Daniudi block can be divided into four stages: Caledonian-Hercynian stage, Indosinian stage, Yanshanian stage and Himalayan stage. Among them, the right-step for left-lateral Taigemiao fault and the left-step for right-lateral northern Shibantai fault were formed from the Caledonian-Hercynian period to the Indosinian period; and the left-step for right-lateral Tuweihe fault and the right-step for left-lateral southern Shibantai fault were formed in the Yanshan period. (3)The formation background and mechanism of strike-slip faults in Daniudi block was affected by the interaction of surrounding plates. The X-type fault system composed of the northern Shibantai fault and Taigemiao fault is related to the collision and compression between the Yangtze plate and the North China craton, while the X-type fault system composed of the southern Shibantai fault and the Tuweihe fault is related to the subduction and compression of the ancient Pacific plate to the Eurasian plate.
2023, 48(6): 2281-2293.
doi: 10.3799/dqkx.2023.007
Abstract:
The architecture of intraplate strike-slip faults plays an important role in controlling reservoir properties as well as hydrocarbon migration and accumulation. In the process of exploration and development of strike-slip fault-controlled fracturing reservoirs, the architecture of the strike-slip fault zone needs to be characterized because of its high heterogeneity. Taking strike-slip fault zones of the Yanchang Formation of the Jinghe oilfield in the southern Ordos basin as an example, in this paper it conducted fault segmentation along the fault strike and lateral zonation along the fault dip by integrating core, logging and seismic data. In this paper it puts forward a method to quantitatively detect damage zone boundaries by cumulative curves of comprehensive fracture index log (CFI) and fault shape index attribute (FSI). The results show that strike-slip fault zones of the Yanchang Formation in the Jinghe oilfield are mainly composed of transtensional and strike-slip segments, and transpressional segments are rarely developed. CFI and FSI are positively correlated with fracture density, and damage zone boundaries can be detected according to the gradient change of the cumulative curves of CFI and FSI. The width of a single fault within the strike-slip fault zones in the Yanchang Formation of the Jinghe oilfield is mainly between 160-300 m, and the average width of transtensional segments is the largest, followed by transpressional and strike-slip segments.
The architecture of intraplate strike-slip faults plays an important role in controlling reservoir properties as well as hydrocarbon migration and accumulation. In the process of exploration and development of strike-slip fault-controlled fracturing reservoirs, the architecture of the strike-slip fault zone needs to be characterized because of its high heterogeneity. Taking strike-slip fault zones of the Yanchang Formation of the Jinghe oilfield in the southern Ordos basin as an example, in this paper it conducted fault segmentation along the fault strike and lateral zonation along the fault dip by integrating core, logging and seismic data. In this paper it puts forward a method to quantitatively detect damage zone boundaries by cumulative curves of comprehensive fracture index log (CFI) and fault shape index attribute (FSI). The results show that strike-slip fault zones of the Yanchang Formation in the Jinghe oilfield are mainly composed of transtensional and strike-slip segments, and transpressional segments are rarely developed. CFI and FSI are positively correlated with fracture density, and damage zone boundaries can be detected according to the gradient change of the cumulative curves of CFI and FSI. The width of a single fault within the strike-slip fault zones in the Yanchang Formation of the Jinghe oilfield is mainly between 160-300 m, and the average width of transtensional segments is the largest, followed by transpressional and strike-slip segments.
2023, 48(6): 2294-2309.
doi: 10.3799/dqkx.2022.476
Abstract:
In order to improve the understanding of strike-slip fault structure and structural characteristics in Ordos basin, based on the coherent slice and the fine interpretation of the 3D seismic data, in this paper it describes in detail and clarifies the plane and profile activity characteristics of the Yudu strike-slip fault zone in the Zhenjing-Binchang area of the southern Ordos basin. Then, it disscusses its formation and evolution process and its control on hydrocarbon accumulation combined with fluid inclusion dating and previous research results. The study shows follows : (1)According to the plane and profile characteristics of the Yudu strike-slip fault zone, the strata in the study area can be divided into upper and lower tectonic layers by the bottom boundary of the Triassic(T8). The Yudu strike-slip fault zone has obvious difference between the upper and lower structural layers. (2) The Yudu strike-slip fault zone has obvious differences in stratification and segmentation, and the fault activity characteristics differ greatly among different strata. Under the action of Caledonian-Hercynian and Yanshanian-Himalayan stresses, the Yudu strike-slip fault zone mainly experienced three stages of tectonic strike-slip activities, namely, sinistral movement in Late Caledonian-Early Hercynian, dextral movement in Late Hercynian and sinistral movement in Yanshanian-Himalayan. (3) Strike-slip faults and their associated fractures play an important role in the migration and accumulation of oil and gas. The main period of oil and gas accumulation in the study area is the late Early Cretaceous, which is consistent with the activity of Yudu strike-slip fault zone in Yanshanian.
In order to improve the understanding of strike-slip fault structure and structural characteristics in Ordos basin, based on the coherent slice and the fine interpretation of the 3D seismic data, in this paper it describes in detail and clarifies the plane and profile activity characteristics of the Yudu strike-slip fault zone in the Zhenjing-Binchang area of the southern Ordos basin. Then, it disscusses its formation and evolution process and its control on hydrocarbon accumulation combined with fluid inclusion dating and previous research results. The study shows follows : (1)According to the plane and profile characteristics of the Yudu strike-slip fault zone, the strata in the study area can be divided into upper and lower tectonic layers by the bottom boundary of the Triassic(T8). The Yudu strike-slip fault zone has obvious difference between the upper and lower structural layers. (2) The Yudu strike-slip fault zone has obvious differences in stratification and segmentation, and the fault activity characteristics differ greatly among different strata. Under the action of Caledonian-Hercynian and Yanshanian-Himalayan stresses, the Yudu strike-slip fault zone mainly experienced three stages of tectonic strike-slip activities, namely, sinistral movement in Late Caledonian-Early Hercynian, dextral movement in Late Hercynian and sinistral movement in Yanshanian-Himalayan. (3) Strike-slip faults and their associated fractures play an important role in the migration and accumulation of oil and gas. The main period of oil and gas accumulation in the study area is the late Early Cretaceous, which is consistent with the activity of Yudu strike-slip fault zone in Yanshanian.
2023, 48(6): 2310-2323.
doi: 10.3799/dqkx.2023.056
Abstract:
Strike-slip fault area unit developed within the southern part of Ordos basin, forming a novel fracture-type tight reservoir, and heavy oil with unknown origin is found within the reservoir. In order to clarify the origin and distribution of heavy oil within the study space and further understand the reservoir - controlling mechanism of fracture-type tight reservoir in strike - slip fault zone, in this paper, the crude oil in the study area was detected by gas chromatography mass spectrometry, and the geochemical characteristics of the crude oil were studied in detail. Then the geochemical characteristics of heavy oil and normal crude oil were compared, and the fracture density in the study area was calculated based on logging data. The relationship between the thickening factors of crude oil and the strike-slip fault zone was analyzed. The results show that the crude oil of Chang 6-Chang 8 member in Jinghe oilfield primarily comes from identical set of source rocks, that is characterised by depositing within the fresh water lake basin with sturdy reducibility, and also the organic matter source is that the mixed input of alga and better plants. There's no obvious distinction between the heavy oil and traditional crude oil within the sedimentary environment, organic matter source and maturity, however there are obvious variations within the degree of biodegradation, heavy oil happiness to grade 3-4 biodegradation. The heavy oil in Jinghe field is principally distributed within splicing tape of the strike-slip fault belt with terribly concentrated little cracks. The strike-slip fault belt has a clear control on the adjustment and preservation of fossil oil, and incorporates a shut relationship with the formation of hevay oil in Jinghe oilfield, that is, it's associated with the dispersion loss of light hydrocarbon and biodegradation compound within the relevant fractures and cracks.
Strike-slip fault area unit developed within the southern part of Ordos basin, forming a novel fracture-type tight reservoir, and heavy oil with unknown origin is found within the reservoir. In order to clarify the origin and distribution of heavy oil within the study space and further understand the reservoir - controlling mechanism of fracture-type tight reservoir in strike - slip fault zone, in this paper, the crude oil in the study area was detected by gas chromatography mass spectrometry, and the geochemical characteristics of the crude oil were studied in detail. Then the geochemical characteristics of heavy oil and normal crude oil were compared, and the fracture density in the study area was calculated based on logging data. The relationship between the thickening factors of crude oil and the strike-slip fault zone was analyzed. The results show that the crude oil of Chang 6-Chang 8 member in Jinghe oilfield primarily comes from identical set of source rocks, that is characterised by depositing within the fresh water lake basin with sturdy reducibility, and also the organic matter source is that the mixed input of alga and better plants. There's no obvious distinction between the heavy oil and traditional crude oil within the sedimentary environment, organic matter source and maturity, however there are obvious variations within the degree of biodegradation, heavy oil happiness to grade 3-4 biodegradation. The heavy oil in Jinghe field is principally distributed within splicing tape of the strike-slip fault belt with terribly concentrated little cracks. The strike-slip fault belt has a clear control on the adjustment and preservation of fossil oil, and incorporates a shut relationship with the formation of hevay oil in Jinghe oilfield, that is, it's associated with the dispersion loss of light hydrocarbon and biodegradation compound within the relevant fractures and cracks.
2023, 48(6): 2324-2341.
doi: 10.3799/dqkx.2022.489
Abstract:
In recent years, Jinghe oilfield has made important breakthroughs in the exploration of fault-fracture body reservoirs around strike-slip fault zones, revealing new fields for hydrocarbon exploration. Deeply understanding of the characteristics of hydrocarbon accumulation and control mechanism in strike-slip fault zone is an important prerequisite for determining the enrichment model of fault-fracture type reservoirs. In this paper, reservoir diagenesis and hydrocarbon charging process have been systematically studied using fluid inclusion technique and calcite ultra-low concentration U-Pb dating and the hydrocarbon distribution characteristics and controlling factors in strike-slip fault zones are also discussed. The results show that there are mainly two stages of early calcite cementation (185±27 Ma and 159±52 Ma, respectively) and the relatively late stage of orange-yellow, blue-green and blue fluorescent oil charge (140.1-96.2 Ma). In strike-slip fault zones, the physical property of crude oil is low in the east and high in the west, the oil production is high in the east and low in the west, and the oil accumulation time is early in the east and late in the west. The carbonate cementation in the Chang 6 and Chang 7 members is weak, and the late blue-green and blue fluorescence oil charges are dominant, but the carbonate cementation of Chang 8 member is intense, which is characterized by three stages of oil charging. On the whole, the strike-slip fault controls the lateral migration of hydrocarbon with high efficiency, but the differences of hydrocarbon enrichment along the strike-slip fault zone is partly controlled by the variation of tectonic stress. The poor original physical property of Chang 6-Chang 7 reservoir and the development of large shale in Chang 7 member limit the vertical fluid transporting ability of strike-slip fault, which leads to fluid predominance and differential accumulation in Chang 8 member. The research results can provide important support for further determining the distribution pattern and oil reservoir-forming model for fault-fracture body reservoirs in the study area.
In recent years, Jinghe oilfield has made important breakthroughs in the exploration of fault-fracture body reservoirs around strike-slip fault zones, revealing new fields for hydrocarbon exploration. Deeply understanding of the characteristics of hydrocarbon accumulation and control mechanism in strike-slip fault zone is an important prerequisite for determining the enrichment model of fault-fracture type reservoirs. In this paper, reservoir diagenesis and hydrocarbon charging process have been systematically studied using fluid inclusion technique and calcite ultra-low concentration U-Pb dating and the hydrocarbon distribution characteristics and controlling factors in strike-slip fault zones are also discussed. The results show that there are mainly two stages of early calcite cementation (185±27 Ma and 159±52 Ma, respectively) and the relatively late stage of orange-yellow, blue-green and blue fluorescent oil charge (140.1-96.2 Ma). In strike-slip fault zones, the physical property of crude oil is low in the east and high in the west, the oil production is high in the east and low in the west, and the oil accumulation time is early in the east and late in the west. The carbonate cementation in the Chang 6 and Chang 7 members is weak, and the late blue-green and blue fluorescence oil charges are dominant, but the carbonate cementation of Chang 8 member is intense, which is characterized by three stages of oil charging. On the whole, the strike-slip fault controls the lateral migration of hydrocarbon with high efficiency, but the differences of hydrocarbon enrichment along the strike-slip fault zone is partly controlled by the variation of tectonic stress. The poor original physical property of Chang 6-Chang 7 reservoir and the development of large shale in Chang 7 member limit the vertical fluid transporting ability of strike-slip fault, which leads to fluid predominance and differential accumulation in Chang 8 member. The research results can provide important support for further determining the distribution pattern and oil reservoir-forming model for fault-fracture body reservoirs in the study area.
2023, 48(6): 2342-2360.
doi: 10.3799/dqkx.2023.092
Abstract:
Strike-slip faults and their reservoir-controlling rules have become the focus of oil and gas exploration, but the internal structural units, transport characteristics and reservoir-controlling rules of different types of strike-slip faults are still unclear. Through detailed fields characterization, physical simulation experiments and typical case analysis, the internal structure of the strike-slip fault and its reservoir control characteristics are revealed. The internal structure of the strike-slip fault includes three units and five zones, including the fault core, the sliding fracture zone on both sides and the induced fracture zone. The fault core of tension-shear strike-slip fault has the best transport, followed by the slip fracture zone and the induced fracture zone. The fault core of compressional or pure torsional strike-slip fault has the best sealing property, followed by induced fracture zone and slip fracture zone. The longitudinal and horizontal transport of tension-shear strike-slip faults is better than that of compression-torsional and pure torsional strike-slip faults. The transport of active disks is better than that of passive disks. The transport of active disks is better than that of static faults. The active disk of the strike-slip fault is characterized by vertical migration of oil and gas in the transport layer while the passive disk is characterized by transverse blocking of oil and gas. The reservoir controlling model of the western strike-slip fault in Jimsar sag, Junggar basin was constructed.
Strike-slip faults and their reservoir-controlling rules have become the focus of oil and gas exploration, but the internal structural units, transport characteristics and reservoir-controlling rules of different types of strike-slip faults are still unclear. Through detailed fields characterization, physical simulation experiments and typical case analysis, the internal structure of the strike-slip fault and its reservoir control characteristics are revealed. The internal structure of the strike-slip fault includes three units and five zones, including the fault core, the sliding fracture zone on both sides and the induced fracture zone. The fault core of tension-shear strike-slip fault has the best transport, followed by the slip fracture zone and the induced fracture zone. The fault core of compressional or pure torsional strike-slip fault has the best sealing property, followed by induced fracture zone and slip fracture zone. The longitudinal and horizontal transport of tension-shear strike-slip faults is better than that of compression-torsional and pure torsional strike-slip faults. The transport of active disks is better than that of passive disks. The transport of active disks is better than that of static faults. The active disk of the strike-slip fault is characterized by vertical migration of oil and gas in the transport layer while the passive disk is characterized by transverse blocking of oil and gas. The reservoir controlling model of the western strike-slip fault in Jimsar sag, Junggar basin was constructed.
2023, 48(6): 2361-2375.
doi: 10.3799/dqkx.2023.090
Abstract:
Xijiang main sag located in the north of Xijiang sag in Zhu Ⅰ depression is characterized by relatively lower paleo-geothermal gradient, thick mudstones in Enping Formation and more magmatism, which resulted in complexity of source rock potential, oil types and oil source, hydrocarbon accumulation and main control factors. Based on the analysis of the organic geochemical characteristics and distributions of the source rocks, oil classification, oil source and oil distribution, the relationships between oil accumulation, magmatism and faults, distribution and potential of the source rocks, the rule of oil accumulation and the main controlling factors could be identified. There are two types of middle-deep lacustrine source rocks with different attributes: the Wenchang Ⅳ Formation and the Wenchang Ⅲ Formation in the Xijiang main sag, which have been strongly transformed and have different hydrocarbon supply capabilities. Two different oil groups have been recognized in Xijiang main sag, which origined from different source rocks and their spatial distributions are different. Group Ⅰ oil origin from the Wenchang Ⅳ Formation source rock, distributed in the rift sequence and depression sequence reservoirs, with long lateral migration distance. Group Ⅱ oil origed in from the Wenchang Ⅲ Formation, only distributed in the rift sequence and accumulated near the sag. Source rocks and faults are two main controlling factors of hydrocarbon accumulation in Xijiang main sag. The difference in attribute and volume of the two type source rocks control the oils' organic geochemical characteristics, the level of hydrocarbon accumulation and the migration distance. The NE trending faults control the development and distribution of source rocks due to the change of segmentation and time-sharing activity rate. The NWW-EW trending faults control the development of the Wenchang Ⅲ Formation source rock, and both control the hydrocarbon accumulation in the rift sequence near the sag and in the depression sequence in the Xijiang middle low uplift far from the sag. The hydrocarbon accumulation pattern could be expressed as source rocks control response on oil accumulation direction, faults control response on reservoir layers, magmatism control response on oil enrichment.
Xijiang main sag located in the north of Xijiang sag in Zhu Ⅰ depression is characterized by relatively lower paleo-geothermal gradient, thick mudstones in Enping Formation and more magmatism, which resulted in complexity of source rock potential, oil types and oil source, hydrocarbon accumulation and main control factors. Based on the analysis of the organic geochemical characteristics and distributions of the source rocks, oil classification, oil source and oil distribution, the relationships between oil accumulation, magmatism and faults, distribution and potential of the source rocks, the rule of oil accumulation and the main controlling factors could be identified. There are two types of middle-deep lacustrine source rocks with different attributes: the Wenchang Ⅳ Formation and the Wenchang Ⅲ Formation in the Xijiang main sag, which have been strongly transformed and have different hydrocarbon supply capabilities. Two different oil groups have been recognized in Xijiang main sag, which origined from different source rocks and their spatial distributions are different. Group Ⅰ oil origin from the Wenchang Ⅳ Formation source rock, distributed in the rift sequence and depression sequence reservoirs, with long lateral migration distance. Group Ⅱ oil origed in from the Wenchang Ⅲ Formation, only distributed in the rift sequence and accumulated near the sag. Source rocks and faults are two main controlling factors of hydrocarbon accumulation in Xijiang main sag. The difference in attribute and volume of the two type source rocks control the oils' organic geochemical characteristics, the level of hydrocarbon accumulation and the migration distance. The NE trending faults control the development and distribution of source rocks due to the change of segmentation and time-sharing activity rate. The NWW-EW trending faults control the development of the Wenchang Ⅲ Formation source rock, and both control the hydrocarbon accumulation in the rift sequence near the sag and in the depression sequence in the Xijiang middle low uplift far from the sag. The hydrocarbon accumulation pattern could be expressed as source rocks control response on oil accumulation direction, faults control response on reservoir layers, magmatism control response on oil enrichment.
2023, 48(6): 2376-2397.
doi: 10.3799/dqkx.2023.091
Abstract:
Forming the theory and technology of unconventional petroleum geology for driving the expansion of exploration and development from conventional to unconventional resources and exploring petroleum inside source kitchen is an inevitable trend in the global petroleum industry. With over 10 years of efforts, we have formed the theories of unconventional fine-grained sedimentology, unconventional reservoir geology, unconventional hydrocarbon accumulation geology, unconventional petroleum development geology, and orderly accumulation of conventional–unconventional petroleum, and developed the key technologies of unconventional petroleum experiment, exploration appraisal, development engineering, and conventional–unconventional petroleum exploration and development, depending upon the distinct geologic setting and petroleum industry conditions in China. These theories and technologies have basically comprised a system framework for unconventional petroleum geology. The evolution from the source control theory for conventional petroleum to the source-reservoir symbiosis system for unconventional petroleum leads to a profound understanding that a huge size of economic resources accumulate in source rock strata and extensive tight reservoir beds in the immediate vicinity. Innovations in the theory and technology of unconventional petroleum geology have guided the unconventional petroleum geology discipline development, research and development of key technologies, formulation of national standards, construction of state laboratories, and professional training, and promoted the economic exploration and development of unconventional resources such as tight oil and gas and shale oil and gas in China. By the end of 2022, unconventional oil and gas production exceeded 1×108 t oil equivalent, accounting for 28% of total oil and gas production in China. Specifically, unconventional gas contributed to 41% of total gas production, and unconventional oil contributed to 17% of total oil production. Oil and gas are non-renewable, but unconventional oil and gas revolution may prolong the life-span of petroleum industry. Through intensifying the innovations in theory, technology and management, and performing "three underground revolutions"(in-situ conversion of low-mature shale for oil and gas, in-situ conversion of oil-rich coal rock for oil and gas, and in-situ fracturing of brittle shale for oil and gas production), it is possible to coordinate the fossil energy and new energy resources in energy super basins represented by Ordos, and shape an integration of petroleum and new energy in energy super basins in China against the background of carbon neutrality. Unconventional oil and gas revolution is expected to sustain the petroleum industry for another 150 years or more and boost China's Energy Independence.
Forming the theory and technology of unconventional petroleum geology for driving the expansion of exploration and development from conventional to unconventional resources and exploring petroleum inside source kitchen is an inevitable trend in the global petroleum industry. With over 10 years of efforts, we have formed the theories of unconventional fine-grained sedimentology, unconventional reservoir geology, unconventional hydrocarbon accumulation geology, unconventional petroleum development geology, and orderly accumulation of conventional–unconventional petroleum, and developed the key technologies of unconventional petroleum experiment, exploration appraisal, development engineering, and conventional–unconventional petroleum exploration and development, depending upon the distinct geologic setting and petroleum industry conditions in China. These theories and technologies have basically comprised a system framework for unconventional petroleum geology. The evolution from the source control theory for conventional petroleum to the source-reservoir symbiosis system for unconventional petroleum leads to a profound understanding that a huge size of economic resources accumulate in source rock strata and extensive tight reservoir beds in the immediate vicinity. Innovations in the theory and technology of unconventional petroleum geology have guided the unconventional petroleum geology discipline development, research and development of key technologies, formulation of national standards, construction of state laboratories, and professional training, and promoted the economic exploration and development of unconventional resources such as tight oil and gas and shale oil and gas in China. By the end of 2022, unconventional oil and gas production exceeded 1×108 t oil equivalent, accounting for 28% of total oil and gas production in China. Specifically, unconventional gas contributed to 41% of total gas production, and unconventional oil contributed to 17% of total oil production. Oil and gas are non-renewable, but unconventional oil and gas revolution may prolong the life-span of petroleum industry. Through intensifying the innovations in theory, technology and management, and performing "three underground revolutions"(in-situ conversion of low-mature shale for oil and gas, in-situ conversion of oil-rich coal rock for oil and gas, and in-situ fracturing of brittle shale for oil and gas production), it is possible to coordinate the fossil energy and new energy resources in energy super basins represented by Ordos, and shape an integration of petroleum and new energy in energy super basins in China against the background of carbon neutrality. Unconventional oil and gas revolution is expected to sustain the petroleum industry for another 150 years or more and boost China's Energy Independence.
2023, 48(6): 2398-2414.
doi: 10.3799/dqkx.2022.188
Abstract:
Investigations and studies on syn- exhumation or post-collisional magmatic rocks can provide key clues to understanding the crust-mantle interactions during the continental subduction and exhumation, and the tectonic evolution of collisional orogenic belts. In this paper it presents a comprehensive research of zircon U-Pb geochronology, petrology, geochemistry and isotopic geology for the syn-exhumation intermediate rocks in the east part of the East Kunlun orogenic belt. And the data could offer new insights into the generation of the syn-exhumation magmatism and the proto-Tethyan tectonic evolution. The results reveal that the Balong and Jinshuikou intermediate rocks yield zircon U-Pb ages of 420 Ma and 405 Ma, respectively, which overlap the exhumation timing of eclogites. The Balong diorite-porphyrite samples have relatively low MgO and Mg# with high K2O, while the Jinshuikou diorite samples have relatively high MgO and Mg# with high Na2O. The Balong diorite-porphyrite samples exhibit decreasing ratios of Nb/La with decreasing Mg#, similar to the features of assimilation and fractional crystallization (AFC). And all of them are plotted on the curve of fractional crystallization. However, the Jinshuikou diorite samples do not show positive correlation between Nb/La and Mg#, and those samples are plotted on the curve of partial melting. In addition, the Balong diorite-porphyrite samples have relatively higher Isr ratios and lower εNd(t) values than those of the Jinshuikou diorite samples. Based on the new petrological, geochemical and isotopic compositions, it concludes that the Balong diorite-porphyrite and the Jinshuikou diorite were respectively derived from basaltic magma differentiation and contamination, and partial melting of the lower crustal basaltic rocks. Combining with new regional studies, it proposes that those intermediate rocks might be formed in a post-collisional extension environment, and slab break-off is the critical factor for triggering the Silurian to Devonian syn-exhumation magmatism. The continental collision and the continental subduction in the East Kunlun region should have initiated at ~440 Ma.
Investigations and studies on syn- exhumation or post-collisional magmatic rocks can provide key clues to understanding the crust-mantle interactions during the continental subduction and exhumation, and the tectonic evolution of collisional orogenic belts. In this paper it presents a comprehensive research of zircon U-Pb geochronology, petrology, geochemistry and isotopic geology for the syn-exhumation intermediate rocks in the east part of the East Kunlun orogenic belt. And the data could offer new insights into the generation of the syn-exhumation magmatism and the proto-Tethyan tectonic evolution. The results reveal that the Balong and Jinshuikou intermediate rocks yield zircon U-Pb ages of 420 Ma and 405 Ma, respectively, which overlap the exhumation timing of eclogites. The Balong diorite-porphyrite samples have relatively low MgO and Mg# with high K2O, while the Jinshuikou diorite samples have relatively high MgO and Mg# with high Na2O. The Balong diorite-porphyrite samples exhibit decreasing ratios of Nb/La with decreasing Mg#, similar to the features of assimilation and fractional crystallization (AFC). And all of them are plotted on the curve of fractional crystallization. However, the Jinshuikou diorite samples do not show positive correlation between Nb/La and Mg#, and those samples are plotted on the curve of partial melting. In addition, the Balong diorite-porphyrite samples have relatively higher Isr ratios and lower εNd(t) values than those of the Jinshuikou diorite samples. Based on the new petrological, geochemical and isotopic compositions, it concludes that the Balong diorite-porphyrite and the Jinshuikou diorite were respectively derived from basaltic magma differentiation and contamination, and partial melting of the lower crustal basaltic rocks. Combining with new regional studies, it proposes that those intermediate rocks might be formed in a post-collisional extension environment, and slab break-off is the critical factor for triggering the Silurian to Devonian syn-exhumation magmatism. The continental collision and the continental subduction in the East Kunlun region should have initiated at ~440 Ma.
2023, 48(6): 2415-2426.
doi: 10.3799/dqkx.2023.063
Abstract:
The response of the powdered sandy soil to the cyclic load in the operation of the metro in small curves is sensitive, especially the centrifugal force on the track when the train is moving particularly serious, and most areas in Zhengzhou belong to the Yellow River alluvial powdered sand layer, so the metro in long-term operation, due to the dynamic response of the powdered sandy soil layer caused by the settlement of the sandy soil layer, to train operation will bring greater potential problems.In this paper, long-term pore water monitoring was carried out, and the MIDAS finite element calculation platform was used to establish a coupled dynamic model of the metro bed-lining-soil for mutual verification, and the vibration response law of the soil around the tunnel was studied for single train operation and two-way meeting, and for different tunnel burial depths. The results show that the pore water pressure is large in the early stage of train operation, and gradually decreases in the later stage and becomes stable. Due to the influence of peak work hours, seasonal climate, and groundwater level, the pore pressure may cause a small increase, but the overall trend is to decline.the simultaneous passage of two-way trains will cause the pore water pressure to increase more than in the case of one-way train operation due to the load superposition effect, the maximum settlement below the tunnel occurs at the left end of the tunnel, the further away from the tunnel the smaller the settlement; at a certain water table, the tunnel burial depth is positively proportional to the pore water pressure magnitude, and inversely proportional to the settlement of the soil around the tunnel.
The response of the powdered sandy soil to the cyclic load in the operation of the metro in small curves is sensitive, especially the centrifugal force on the track when the train is moving particularly serious, and most areas in Zhengzhou belong to the Yellow River alluvial powdered sand layer, so the metro in long-term operation, due to the dynamic response of the powdered sandy soil layer caused by the settlement of the sandy soil layer, to train operation will bring greater potential problems.In this paper, long-term pore water monitoring was carried out, and the MIDAS finite element calculation platform was used to establish a coupled dynamic model of the metro bed-lining-soil for mutual verification, and the vibration response law of the soil around the tunnel was studied for single train operation and two-way meeting, and for different tunnel burial depths. The results show that the pore water pressure is large in the early stage of train operation, and gradually decreases in the later stage and becomes stable. Due to the influence of peak work hours, seasonal climate, and groundwater level, the pore pressure may cause a small increase, but the overall trend is to decline.the simultaneous passage of two-way trains will cause the pore water pressure to increase more than in the case of one-way train operation due to the load superposition effect, the maximum settlement below the tunnel occurs at the left end of the tunnel, the further away from the tunnel the smaller the settlement; at a certain water table, the tunnel burial depth is positively proportional to the pore water pressure magnitude, and inversely proportional to the settlement of the soil around the tunnel.
