The Bozhong Sag is the largest petroliferous sag in the Bohai Bay Basin,and the source rocks of Paleogene Dongying and Shahejie Formations were buried deeply.Most of the drillings were located at the structural high,a...The Bozhong Sag is the largest petroliferous sag in the Bohai Bay Basin,and the source rocks of Paleogene Dongying and Shahejie Formations were buried deeply.Most of the drillings were located at the structural high,and there were few wells that met good quality source rocks,so it is difficult to evaluate the source rocks in the study area precisely by geochemical analysis only.Based on the Rock-Eval pyrolysis,total organic carbon(TOC)testing,the organic matter(OM)abundance of Paleogene source rocks in the southwestern Bozhong Sag were evaluated,including the lower of second member of Dongying Formation(E_(3)d2L),the third member of Dongying Formation(E_(3)d_(3)),the first and second members of Shahejie Formation(E_(2)s_(1+2)),the third member of Shahejie Formation(E_(2)s_(3)).The results indicate that the E_(2)s_(1+2)and E_(2)s_(3)have better hydrocarbon generative potentials with the highest OM abundance,the E_(3)d_(3)are of the second good quality,and the E_(3)d2L have poor to fair hydrocarbon generative potential.Furthermore,the well logs were applied to predict TOC and residual hydrocarbon generation potential(S_(2))based on the sedimentary facies classification,usingΔlogR,generalizedΔlogR,logging multiple linear regression and BP neural network methods.The various methods were compared,and the BP neural network method have relatively better prediction accuracy.Based on the pre-stack simultaneous inversion(P-wave impedance,P-wave velocity and density inversion results)and the post-stack seismic attributes,the three-dimensional(3D)seismic prediction of TOC and S_(2)was carried out.The results show that the seismic near well prediction results of TOC and S_(2)based on seismic multi-attributes analysis correspond well with the results of well logging methods,and the plane prediction results are identical with the sedimentary facies map in the study area.The TOC and S_(2)values of E_(2)s_(1+2)and E_(2)s_(3)are higher than those in E_(3)d_(3)and E_(3)d_(2)L,basically consistent with the geochemical analysis results.This method makes up the deficiency of geochemical methods,establishing the connection between geophysical information and geochemical data,and it is helpful to the 3D quantitative prediction and the evaluation of high-quality source rocks in the areas where the drillings are limited.展开更多
The hazards of fault reactivation caused by fluid injection are a growing concern.However,traditional evaluation methods of fault stability are likely to underestimate the risk in fault segments with a high clay conte...The hazards of fault reactivation caused by fluid injection are a growing concern.However,traditional evaluation methods of fault stability are likely to underestimate the risk in fault segments with a high clay content.Therefore,an extended evaluation method of fault stability(ECPP)incorporating the heterogeneity in friction strength caused by variation in the clay content within the fault zone is established in this study.After characterizing the current stress field of the BZ34-2 Oilfield in the Huanghekou Sag,Bohai Bay Basin,the reactivation potential of faults is evaluated using both traditional and ECPP methods.Traditional evaluation of fault stability shows that all faults are stable in the present stress field.Faults oriented ENE have a relatively high risk.The maximum sustainable fluid pressure Δp is approximately 8.8-8.9 MPa and 9.3-9.9 MPa.When considering the heterogeneity in fault friction strength,the fault stability is clearly controlled by the clay content of the faults.The high-risk fault segments assessed using traditional methods are no longer obvious,which reflects the importance of incorporating friction strength heterogeneity in the process of fault evaluation.Moreover,the results also show that most fault segments are activated when the fault zone is dominated by montmorillonite,reflecting the strong influence of clay mineral types on fault stability.The factors influencing the heterogeneity of fault friction strength are very complicated in actual situations.Therefore,future work should focus on establishing a database through a large number of experiments and investigating the relationship between the friction coefficient and the main controlling factors.展开更多
Based on the theory of structural analysis,the characteristics and structural patterns of subtle faults are studied using 3D seismic data of the Bohai Sea to analyze the development process and origin of the subtle fa...Based on the theory of structural analysis,the characteristics and structural patterns of subtle faults are studied using 3D seismic data of the Bohai Sea to analyze the development process and origin of the subtle faults.A method of identifying subtle faults is proposed,forming a complete system for analyzing origins of subtle faults in the Bohai Sea.The complex strike-slip fault patterns under the strike-slip and extension stress background,diverse formation rocks,and strong neotectonic movement are the reasons for the development of subtle faults.According to the tectonic origin and development location,the subtle faults in Bohai Sea can be divided into 12 types in the three categories of strike slip dominant,extension dominant and strike slip and extension composite,and the different types of subtle faults occur in different regions of the Bohai Sea.Unreasonable variation of sedimentary stratum thickness,inherited distortion or even abrupt change of stratum occurrence,zonation of plane fault combination and the variation of oil-water system in the same structure with no-lithologic change are the important signs for identifying subtle faults in Bohai Sea.The subtle faults greatly enlarge the size of the structural trap groups,and areas with dense subtle faults are often active area of hydrocarbon migration and accumulation and favorable exploration zones,which have strong control on the hydrocarbon accumulation.The identification method for subtle faults has guided the exploration in the mature areas of Bohai Sea effectively,with a number of large and medium oil and gas fields discovered,such as Bozhong 29-6 and Penglai 20-2.展开更多
Despite the absence of regional cap rocks in the Lower Paleozoic for the entire Tazhong Low Rise,several sets of effective local cap rocks are well preserved on the Northern Slope.Of these the best is the Ordovician m...Despite the absence of regional cap rocks in the Lower Paleozoic for the entire Tazhong Low Rise,several sets of effective local cap rocks are well preserved on the Northern Slope.Of these the best is the Ordovician mudstone of the Sangtamu Formation; the second is the Silurian Red Mudstone Member of the Tatairtag Formation and the marl of the Ordovician Lianglitag Formation; and the third is the gray mudstone of the Silurian Kepingtag Formation.The dense limestone of the Ordovician Yingshan Formation and the gypsum of the Middle Cambrian have shown initial sealing capacity.These effective cap rocks are closely related to the distribution of Lower Palaeozoic hydrocarbons in the Tazhong Low Rise.With well-preserved Sangtamu Formation mudstone and its location close to migration pathways,rich Lower Paleozoic hydrocarbon accumulation can be found on the Northem Slope.Vertically,most of the reserves are distributed below the Sangtamu Formation mudstone; areally,hydrocarbons are mainly found in the areas with well-developed Sangtamu Formation mudstone and Lianglitag Formation marl.Burial history and hydrocarbon charging history show that the evolution of Lower Palaeozoic cap rocks controlled the accumulation of hydrocarbon in the Tazhong Low Rise.Take the Red Mudstone Member of the Tatairtag Formation and Sangtamu Formation mudstone for examples：1） In the hydrocarbon charging time of the Late Caledonian-Early Hercynian,with top surfaces at burial depths of over 1,100 m,the cap rocks were able to seal oil and gas; 2） During the intense uplifting of the Devonian,the cap rocks with top surfaces at burial depths of 200-800 m and 500-1,100 m respectively were denuded in local areas,thus hydrocarbons trapped in earlier time were degraded to widespread bitumen; 3） In the hydrocarbon charging time of the Late Hercynian and Himalayan,the top surfaces of the cap rocks were at burial depths of over 2,000 m without intense uplifting and denudation thereafter,so trapped hydrocarbons were preserved.Based on cap rocks,the Ordovician Penglaiba Formation and Lower Cambrian dolomite could be potential targets for exploration on the Tazhong Northern Slope,and combined with hydrocarbon migration,less risk would be involved.展开更多
Based on the 3 D seismic structure interpretation of Bohai Sea, combined with physical modeling of structure, structural style analysis and apatite fission track simulation, the structural characteristics and genetic ...Based on the 3 D seismic structure interpretation of Bohai Sea, combined with physical modeling of structure, structural style analysis and apatite fission track simulation, the structural characteristics and genetic mechanism of the Cenozoic strike-slip faults in Bohai Sea were investigated. The results show that Tanlu strike-slip fault experienced three stages of strike-slip activities in the Cenozoic,and the transition from left-lateral strike to right-lateral strike-slip was completed at the end of the fourth member of the Shahejie Formation. The strike-slip faults in the Bohai Sea have the characteristics of multi-stage and multi-strength stress superposition. According to the superimposed forms of different strengths, different properties and different ratios, they can be divided into three major genetic types,extension and strike-slip superimposition, extension and extrusion superimposition, extrusion and strike-slip superimposition, and fifteen typical structure patterns. Affected by multiple changes in the direction and rate of subduction of the Cenozoic Pacific plate, the difference between the Cenozoic extension and the strike-slip in the Bohai Sea area leads to the diversity of the fault system and the zoning of the depression structure. According to superimposition features of faults, the Bohai Sea area can be divided into the Liaoxi S-type weak strike-slip zone, Liaodong braided strong strike-slip zone, Boxi conjugated medium strike-slip zone, Bodong brush structure medium strike-slip zone and Bonan parallel strong strike-slip zone. These zones differ in oil and gas accumulation features.展开更多
The structural style, fault activity, strike-slip displacement, and the formation mechanism and hydrocarbon migration and accumulation in the center tectonic zone in the northeast Shaleitian Bulge of Zhangjiakou-Pengl...The structural style, fault activity, strike-slip displacement, and the formation mechanism and hydrocarbon migration and accumulation in the center tectonic zone in the northeast Shaleitian Bulge of Zhangjiakou-Penglai Fault Zone were studied by seismic attribute analysis, structural geometric analysis, fault activity analysis, structure evolution history and simulation of hydrocarbon migration, based on 3-D seismic and drilling data. The main results are as follows:(1) The study area is a superimposed tectonic zone, which experienced early(Paleocene and Eocene) extension and late(Oligocene and Pliocene-Quaternary) strike-slip and pull-apart.(2) The sinistral strike slip of the northeast Shaleitian Bulge of Zhangjiakou-Penglai Fault Zone went through two periods, Oligocene and Pliocene-Quaternary, and the Bohai section was active earlier than the inland section.(3) The sinistral strike slip displacement of Zhangjiakou-Penglai Fault is 4 km since Cenozoic, including 1 km in the Oligocene, and 3 km in the Pliocene-Quaternary.(4) The strike-slip movements have resulted in the increase of fault activity and basin-mountain restructure in the fault zone, also contributed to the formation of the central tectonic belt and the conjugate evolution in north-east structural belt.(5) The conjugate strike slip of the Zhangjiakou-Penglai Fault Zone dominated the migration and accumulation of hydrocarbon in shallow formations by controlling the injection points and segments of hydrocarbon from the deep layers to shallow layers.展开更多
Based on well logging responses,sedimentary patterns and sandstone thickness,the distribution characteristics of meandering river sedimentary sand body of Neogene Minghuazhen Formation NmⅢ2 layer in the west of Shiji...Based on well logging responses,sedimentary patterns and sandstone thickness,the distribution characteristics of meandering river sedimentary sand body of Neogene Minghuazhen Formation NmⅢ2 layer in the west of Shijiutuo Bulge,Chengning Uplift,Bohai Bay Basin were investigated.A new approach to calculate the occurrence of the sand-mudstone interfaces using resistivity log of horizontal well was advanced to solve the multiple solution problem of abandoned channel’s orientation.This method uses the trigonometric function relationship between radius,dip and length of the resistivity log to calculate the occurrence qualitatively-quantitatively to help determine the true direction of the abandoned channels.This method can supplement and improve the architecture dissection technique for meandering river sandbodies.This method was used to study the dip angle and scale of the lateral accretion layers in point bar quantitatively to help determine the spatial distribution of lateral accretion layers.The fine architecture model of underground meandering river reservoir in the study area has been established.Different from traditional grids,different grid densities for lateral accretion layers and bodies were used in this model by non-uniform upscaling to establish the inner architecture model of point-bars and realize industrial numerical simulation of the whole study area.The research results can help us predict the distribution of remaining oil,tap remaining oil,and optimize the waterflooding in oilfields.展开更多
Based on 3D seismic data, the evolution mechanism and characteristics of faults were investigated to reveal the structural origin and its control on differential hydrocarbon accumulation through comprehensive analyses...Based on 3D seismic data, the evolution mechanism and characteristics of faults were investigated to reveal the structural origin and its control on differential hydrocarbon accumulation through comprehensive analyses, including structure style analysis, fault activity analysis, analogue modelling and comparison among the wells. The complex fault system with differently trending faults resulted from strike-slip and rifting in Paleogene was partly activated, developed successively and stretched obliquely by the near-NS extensional stress field in Neogene. In the area little affected by pre-existing faults, new faults nearly perpendicular to the extension direction developed. The structural development in the study area was not caused by transpressional strike slip. Under the oblique extension effect of pre-existing faults, if the angle between the strike of pre-existing fault and the extensional direction is different, the strike-slip and extensional stresses are different in ratio. The larger the angle between the two is, the stronger the extensional component, the poorer the sealing ability of the fault, and the stronger the oil and gas migration capacity will be. Conversely, the smaller the angle between the two is, the stronger the strike-slip component, the better the sealing ability of the fault, and the poorer the oil and gas migration capacity will be. The accumulation condition analysis results considering the fault trend are in good agreement with the oil and gas shows in wells drilled in this area.展开更多
Reservoir connectivity is a critical issue in the process of oil-gas exploration and development. According to the theory of fluid mechanics and the achievements of many scholars, a connected reservoir coincides with ...Reservoir connectivity is a critical issue in the process of oil-gas exploration and development. According to the theory of fluid mechanics and the achievements of many scholars, a connected reservoir coincides with a unified formation pressure system;there is a linear relationship between formation pressure and depth in normal pressure system reservoir. However, in high-permeability or multi-phase fluid reservoirs, this method has poor applicability and limitations. Through theoretical analysis and formula derivation, a new method for judging the connectivity of normal pressure reservoirs is found, that is, the inverse proportional function relationship between the pressure coefficient and the depth. In this paper, the relationship between the pressure system and the inverse proportional function has been verified. The function of the same pressure system is unique, monotonic, and has unified asymptote and symmetry axis and vice versa. Examples show that the inverse proportional function is more accurate and reliable for judging reservoir connectivity than the linear function.展开更多
文摘The Bozhong Sag is the largest petroliferous sag in the Bohai Bay Basin,and the source rocks of Paleogene Dongying and Shahejie Formations were buried deeply.Most of the drillings were located at the structural high,and there were few wells that met good quality source rocks,so it is difficult to evaluate the source rocks in the study area precisely by geochemical analysis only.Based on the Rock-Eval pyrolysis,total organic carbon(TOC)testing,the organic matter(OM)abundance of Paleogene source rocks in the southwestern Bozhong Sag were evaluated,including the lower of second member of Dongying Formation(E_(3)d2L),the third member of Dongying Formation(E_(3)d_(3)),the first and second members of Shahejie Formation(E_(2)s_(1+2)),the third member of Shahejie Formation(E_(2)s_(3)).The results indicate that the E_(2)s_(1+2)and E_(2)s_(3)have better hydrocarbon generative potentials with the highest OM abundance,the E_(3)d_(3)are of the second good quality,and the E_(3)d2L have poor to fair hydrocarbon generative potential.Furthermore,the well logs were applied to predict TOC and residual hydrocarbon generation potential(S_(2))based on the sedimentary facies classification,usingΔlogR,generalizedΔlogR,logging multiple linear regression and BP neural network methods.The various methods were compared,and the BP neural network method have relatively better prediction accuracy.Based on the pre-stack simultaneous inversion(P-wave impedance,P-wave velocity and density inversion results)and the post-stack seismic attributes,the three-dimensional(3D)seismic prediction of TOC and S_(2)was carried out.The results show that the seismic near well prediction results of TOC and S_(2)based on seismic multi-attributes analysis correspond well with the results of well logging methods,and the plane prediction results are identical with the sedimentary facies map in the study area.The TOC and S_(2)values of E_(2)s_(1+2)and E_(2)s_(3)are higher than those in E_(3)d_(3)and E_(3)d_(2)L,basically consistent with the geochemical analysis results.This method makes up the deficiency of geochemical methods,establishing the connection between geophysical information and geochemical data,and it is helpful to the 3D quantitative prediction and the evaluation of high-quality source rocks in the areas where the drillings are limited.
基金the financial support from the National Natural Science Foundation of China(Grant Nos.42002152 and U20A2093)National Key Research and Development Program of China(Grant No.2022YFE0206800).
文摘The hazards of fault reactivation caused by fluid injection are a growing concern.However,traditional evaluation methods of fault stability are likely to underestimate the risk in fault segments with a high clay content.Therefore,an extended evaluation method of fault stability(ECPP)incorporating the heterogeneity in friction strength caused by variation in the clay content within the fault zone is established in this study.After characterizing the current stress field of the BZ34-2 Oilfield in the Huanghekou Sag,Bohai Bay Basin,the reactivation potential of faults is evaluated using both traditional and ECPP methods.Traditional evaluation of fault stability shows that all faults are stable in the present stress field.Faults oriented ENE have a relatively high risk.The maximum sustainable fluid pressure Δp is approximately 8.8-8.9 MPa and 9.3-9.9 MPa.When considering the heterogeneity in fault friction strength,the fault stability is clearly controlled by the clay content of the faults.The high-risk fault segments assessed using traditional methods are no longer obvious,which reflects the importance of incorporating friction strength heterogeneity in the process of fault evaluation.Moreover,the results also show that most fault segments are activated when the fault zone is dominated by montmorillonite,reflecting the strong influence of clay mineral types on fault stability.The factors influencing the heterogeneity of fault friction strength are very complicated in actual situations.Therefore,future work should focus on establishing a database through a large number of experiments and investigating the relationship between the friction coefficient and the main controlling factors.
基金Supported by the China National Science and Technology Major Project(2016ZX05024-003)CNOOC Science and Technology Major Project(CNOOC-KJ135ZDXM36TJ08TJ)。
文摘Based on the theory of structural analysis,the characteristics and structural patterns of subtle faults are studied using 3D seismic data of the Bohai Sea to analyze the development process and origin of the subtle faults.A method of identifying subtle faults is proposed,forming a complete system for analyzing origins of subtle faults in the Bohai Sea.The complex strike-slip fault patterns under the strike-slip and extension stress background,diverse formation rocks,and strong neotectonic movement are the reasons for the development of subtle faults.According to the tectonic origin and development location,the subtle faults in Bohai Sea can be divided into 12 types in the three categories of strike slip dominant,extension dominant and strike slip and extension composite,and the different types of subtle faults occur in different regions of the Bohai Sea.Unreasonable variation of sedimentary stratum thickness,inherited distortion or even abrupt change of stratum occurrence,zonation of plane fault combination and the variation of oil-water system in the same structure with no-lithologic change are the important signs for identifying subtle faults in Bohai Sea.The subtle faults greatly enlarge the size of the structural trap groups,and areas with dense subtle faults are often active area of hydrocarbon migration and accumulation and favorable exploration zones,which have strong control on the hydrocarbon accumulation.The identification method for subtle faults has guided the exploration in the mature areas of Bohai Sea effectively,with a number of large and medium oil and gas fields discovered,such as Bozhong 29-6 and Penglai 20-2.
基金supported by the National Natural Science Foundation of China(No.41072102)National Key Basic Research Development Plan("973"Project,No.2005CB422108)National Major Projects(Nos.2008ZX05004-004,2011ZX05005-001)
文摘Despite the absence of regional cap rocks in the Lower Paleozoic for the entire Tazhong Low Rise,several sets of effective local cap rocks are well preserved on the Northern Slope.Of these the best is the Ordovician mudstone of the Sangtamu Formation; the second is the Silurian Red Mudstone Member of the Tatairtag Formation and the marl of the Ordovician Lianglitag Formation; and the third is the gray mudstone of the Silurian Kepingtag Formation.The dense limestone of the Ordovician Yingshan Formation and the gypsum of the Middle Cambrian have shown initial sealing capacity.These effective cap rocks are closely related to the distribution of Lower Palaeozoic hydrocarbons in the Tazhong Low Rise.With well-preserved Sangtamu Formation mudstone and its location close to migration pathways,rich Lower Paleozoic hydrocarbon accumulation can be found on the Northem Slope.Vertically,most of the reserves are distributed below the Sangtamu Formation mudstone; areally,hydrocarbons are mainly found in the areas with well-developed Sangtamu Formation mudstone and Lianglitag Formation marl.Burial history and hydrocarbon charging history show that the evolution of Lower Palaeozoic cap rocks controlled the accumulation of hydrocarbon in the Tazhong Low Rise.Take the Red Mudstone Member of the Tatairtag Formation and Sangtamu Formation mudstone for examples：1） In the hydrocarbon charging time of the Late Caledonian-Early Hercynian,with top surfaces at burial depths of over 1,100 m,the cap rocks were able to seal oil and gas; 2） During the intense uplifting of the Devonian,the cap rocks with top surfaces at burial depths of 200-800 m and 500-1,100 m respectively were denuded in local areas,thus hydrocarbons trapped in earlier time were degraded to widespread bitumen; 3） In the hydrocarbon charging time of the Late Hercynian and Himalayan,the top surfaces of the cap rocks were at burial depths of over 2,000 m without intense uplifting and denudation thereafter,so trapped hydrocarbons were preserved.Based on cap rocks,the Ordovician Penglaiba Formation and Lower Cambrian dolomite could be potential targets for exploration on the Tazhong Northern Slope,and combined with hydrocarbon migration,less risk would be involved.
基金Supported by the China National Science and Technology Major Project(2016ZX05024-002,2016ZX05024-003)
文摘Based on the 3 D seismic structure interpretation of Bohai Sea, combined with physical modeling of structure, structural style analysis and apatite fission track simulation, the structural characteristics and genetic mechanism of the Cenozoic strike-slip faults in Bohai Sea were investigated. The results show that Tanlu strike-slip fault experienced three stages of strike-slip activities in the Cenozoic,and the transition from left-lateral strike to right-lateral strike-slip was completed at the end of the fourth member of the Shahejie Formation. The strike-slip faults in the Bohai Sea have the characteristics of multi-stage and multi-strength stress superposition. According to the superimposed forms of different strengths, different properties and different ratios, they can be divided into three major genetic types,extension and strike-slip superimposition, extension and extrusion superimposition, extrusion and strike-slip superimposition, and fifteen typical structure patterns. Affected by multiple changes in the direction and rate of subduction of the Cenozoic Pacific plate, the difference between the Cenozoic extension and the strike-slip in the Bohai Sea area leads to the diversity of the fault system and the zoning of the depression structure. According to superimposition features of faults, the Bohai Sea area can be divided into the Liaoxi S-type weak strike-slip zone, Liaodong braided strong strike-slip zone, Boxi conjugated medium strike-slip zone, Bodong brush structure medium strike-slip zone and Bonan parallel strong strike-slip zone. These zones differ in oil and gas accumulation features.
基金Supported by the China National Science and Technology Major Project(2016ZX05024-003)
文摘The structural style, fault activity, strike-slip displacement, and the formation mechanism and hydrocarbon migration and accumulation in the center tectonic zone in the northeast Shaleitian Bulge of Zhangjiakou-Penglai Fault Zone were studied by seismic attribute analysis, structural geometric analysis, fault activity analysis, structure evolution history and simulation of hydrocarbon migration, based on 3-D seismic and drilling data. The main results are as follows:(1) The study area is a superimposed tectonic zone, which experienced early(Paleocene and Eocene) extension and late(Oligocene and Pliocene-Quaternary) strike-slip and pull-apart.(2) The sinistral strike slip of the northeast Shaleitian Bulge of Zhangjiakou-Penglai Fault Zone went through two periods, Oligocene and Pliocene-Quaternary, and the Bohai section was active earlier than the inland section.(3) The sinistral strike slip displacement of Zhangjiakou-Penglai Fault is 4 km since Cenozoic, including 1 km in the Oligocene, and 3 km in the Pliocene-Quaternary.(4) The strike-slip movements have resulted in the increase of fault activity and basin-mountain restructure in the fault zone, also contributed to the formation of the central tectonic belt and the conjugate evolution in north-east structural belt.(5) The conjugate strike slip of the Zhangjiakou-Penglai Fault Zone dominated the migration and accumulation of hydrocarbon in shallow formations by controlling the injection points and segments of hydrocarbon from the deep layers to shallow layers.
基金Supported by the China National Science and Technology Major Project(2008ZX05030-005-012011ZX05004-004-007).
文摘Based on well logging responses,sedimentary patterns and sandstone thickness,the distribution characteristics of meandering river sedimentary sand body of Neogene Minghuazhen Formation NmⅢ2 layer in the west of Shijiutuo Bulge,Chengning Uplift,Bohai Bay Basin were investigated.A new approach to calculate the occurrence of the sand-mudstone interfaces using resistivity log of horizontal well was advanced to solve the multiple solution problem of abandoned channel’s orientation.This method uses the trigonometric function relationship between radius,dip and length of the resistivity log to calculate the occurrence qualitatively-quantitatively to help determine the true direction of the abandoned channels.This method can supplement and improve the architecture dissection technique for meandering river sandbodies.This method was used to study the dip angle and scale of the lateral accretion layers in point bar quantitatively to help determine the spatial distribution of lateral accretion layers.The fine architecture model of underground meandering river reservoir in the study area has been established.Different from traditional grids,different grid densities for lateral accretion layers and bodies were used in this model by non-uniform upscaling to establish the inner architecture model of point-bars and realize industrial numerical simulation of the whole study area.The research results can help us predict the distribution of remaining oil,tap remaining oil,and optimize the waterflooding in oilfields.
基金Supported by the China National Science and Technology Major Project(2016ZX05024-002-006)
文摘Based on 3D seismic data, the evolution mechanism and characteristics of faults were investigated to reveal the structural origin and its control on differential hydrocarbon accumulation through comprehensive analyses, including structure style analysis, fault activity analysis, analogue modelling and comparison among the wells. The complex fault system with differently trending faults resulted from strike-slip and rifting in Paleogene was partly activated, developed successively and stretched obliquely by the near-NS extensional stress field in Neogene. In the area little affected by pre-existing faults, new faults nearly perpendicular to the extension direction developed. The structural development in the study area was not caused by transpressional strike slip. Under the oblique extension effect of pre-existing faults, if the angle between the strike of pre-existing fault and the extensional direction is different, the strike-slip and extensional stresses are different in ratio. The larger the angle between the two is, the stronger the extensional component, the poorer the sealing ability of the fault, and the stronger the oil and gas migration capacity will be. Conversely, the smaller the angle between the two is, the stronger the strike-slip component, the better the sealing ability of the fault, and the poorer the oil and gas migration capacity will be. The accumulation condition analysis results considering the fault trend are in good agreement with the oil and gas shows in wells drilled in this area.
文摘Reservoir connectivity is a critical issue in the process of oil-gas exploration and development. According to the theory of fluid mechanics and the achievements of many scholars, a connected reservoir coincides with a unified formation pressure system;there is a linear relationship between formation pressure and depth in normal pressure system reservoir. However, in high-permeability or multi-phase fluid reservoirs, this method has poor applicability and limitations. Through theoretical analysis and formula derivation, a new method for judging the connectivity of normal pressure reservoirs is found, that is, the inverse proportional function relationship between the pressure coefficient and the depth. In this paper, the relationship between the pressure system and the inverse proportional function has been verified. The function of the same pressure system is unique, monotonic, and has unified asymptote and symmetry axis and vice versa. Examples show that the inverse proportional function is more accurate and reliable for judging reservoir connectivity than the linear function.
