Transfer zones are structural areas of faults interactions where fault motion or displacement can be transferred from one fault to another, regional strain maintains laterally constant. Transfer zones are widely devel...Transfer zones are structural areas of faults interactions where fault motion or displacement can be transferred from one fault to another, regional strain maintains laterally constant. Transfer zones are widely developed in rift basins and have significance on hydrocarbon accumulation. In this review article, we attempt to summarize recent advances on the types, distance-displacement curves, evolutionary stages and controlling factors of transfer zones in rift basins and their effects on sedimentary systems, reservoir properties, trap formation and hydrocarbon migration. The formation of transfer zones is genetically related to the segmented growth of normal faults. Depending on the degree of interaction between these normal faults, transfer zones in rift basins could be divided into two types: soft-linked and hard-linked, which are further subdivided into transfer slope, oblique anticline, horst and transfer fault based on the combination patterns of normal faults. In general, the development of transfer zones experiences several stages including isolated normal faulting, transfer slope forming, complicating and breaking. During the interaction and growth of segmented normal faults, stress-strain and spatial array of faults, pre-existing basement structures, and mechanical conditions of rocks have a great influence on the location and development processes of transfer zones. A transfer zone is commonly considered as a pathway for conveying sediments from provenance to basin, and it hence exerts an essential control on the distribution of sandbodies. In addition, transfer zone is the area where stresses are concentrated, which facilitates the formation of various types of structural traps, and it is also a favorable conduit for hydrocarbon migration. Consequently, there exists great hydrocarbon potentials in transfer zones to which more attention should be given.展开更多
According to the latest drilling and the analysis of the burial history,source rock evolution history and hydrocarbon accumulation history,the sub-source hydrocarbon accumulation characteristics of the Permian reservo...According to the latest drilling and the analysis of the burial history,source rock evolution history and hydrocarbon accumulation history,the sub-source hydrocarbon accumulation characteristics of the Permian reservoirs in the Jinan Sag,eastern Junggar Basin,are clarified,and the hydrocarbon accumulation model of these reservoirs is established.The results are obtained in four aspects.First,the main body of the thick salified lake basin source rocks in the Lucaogou Formation has reached the mature stage with abundant resource base.Large-scale reservoirs are developed in the Jingjingzigou,Wutonggou and Lucaogou formations.Vertically,there are multiple sets of good regional seals,the source-reservoir-caprock assemblage is good,and there are three reservoir-forming assemblages:sub-source,intra-source and above-source.Second,dissolution,hydrocarbon charging and pore-preserving effect,and presence of chlorite film effectively increase the sub-source pore space.Oil charging is earlier than the time when the reservoir becomes densified,which improves the efficiency of hydrocarbon accumulation.Third,buoyancy and source-reservoir pressure difference together constitute the driving force of oil charging,and the micro-faults within the formation give the advantage of"source-reservoir lateral docking"under the source rock.Microfractures can be critical channels for efficient seepage and continuous charging of oil in different periods.Fourth,the Jingjingzigou Formation experienced three periods of oil accumulation in the Middle-Late Permian,Middle-Late Jurassic and Late Neogene,with the characteristics of long-distance migration and accumulation in early stage,mixed charging and accumulation in middle stage and short-distance migration and high-position accumulation in late stage.The discovery and theoretical understanding of the Permian reservoirs in the Jinan Sag reveal that the thrust belt has good conditions for forming large reservoirs,and it is promising for exploration.The study results are of guidance and reference significance for oil and gas exploration in the Jinan Sag and other geologically similar areas.展开更多
Understanding hydrocarbon migration and accumulation mechanisms is one of the key scientif ic problems that should be solved for effective hydrocarbon exploration in the superimposed basins developed in northwest Chin...Understanding hydrocarbon migration and accumulation mechanisms is one of the key scientif ic problems that should be solved for effective hydrocarbon exploration in the superimposed basins developed in northwest China. The northwest striking No.1 slope break zone, which is a representative of superimposed basins in the Tarim Basin, can be divided into five parts due to the intersection of the northeast strike-slip faults. Controlled by the tectonic framework, the types and properties of reservoirs and the hydrocarbon compositions can also be divided into five parts from east to west. Anomalies of all the parameters were found on the fault intersection zone and weakened up-dip along the structural ridge away from it. Thus, it can be inferred that the intersection zone is the hydrocarbon charging position. This new conclusion differs greatly from the traditional viewpoint, which believes that the hydrocarbon migrates and accumulates along the whole plane of the No.1 slope break zone. The viewpoint is further supported by the evidence from the theory of main pathway systems, obvious improvement of the reservoir quality (2-3 orders of magnitude at the intersection zone) and the formation mechanisms of the fault intersection zone. Differential hydrocarbon migration and entrapment exists in and around the strike- slip faults. This is controlled by the internal structure of faults. It is concluded that the more complicated the fault structure is, the more significant the effects will be. If there is a deformation band, it will hinder the cross fault migration due to the common feature of two to four orders of magnitude reduction in permeability. Otherwise, hydrocarbons tend to accumulate in the up-dip structure under the control of buoyancy. Further research on the internal fault structure should be emphasized.展开更多
The development, evolution and formation mechanism of faults and their control on the migration and accumulation of Mesozoic oil and gas in the middle-shallow layers of the slope zone of Mahu sag were studied by the i...The development, evolution and formation mechanism of faults and their control on the migration and accumulation of Mesozoic oil and gas in the middle-shallow layers of the slope zone of Mahu sag were studied by the interpretation of seismic and drilling data. Two types of faults, normal and strike-slip, are developed in the middle-shallow layers of the slope zone of the Mahu sag and they are mostly active in the Yanshanian period. They are divided into four grade faults: The grade I strike-slip faults with NWW to near EW direction are related to the left-lateral transpressive fault zones in the northwest of Junggar Basin since the end of the Triassic. The grade II faults with NE to NNE direction are the normal faults located at the junction of the fault zone and the slope zone, and their formation is related to the extension at the top of the nose-like structures in the fault zone. The grade III faults, which are also the normal faults, are the result of the extension at the top of the lower uplifts in the slope zone and differential compaction. The grade IV faults with NE direction are normal faults, which may be related to the extension environment at the tip of the lower uplifts. Faults not only are the channel for the vertical migration of oil and gas, but also control the oil-gas accumulation. There are two types of oil-gas reservoirs in the middle-shallow layers of slope zone of Mahu sag: fault block reservoirs and fault-lithologic reservoirs. They have large traps and promising exploration potential.展开更多
The hydro-geologic stages in the Biyang Depression, Henan Province, were defined and factors controlling the evolution of the hydrodynamic field in this area were analyzed. The evolution of the paleo-hydrodynamic fiel...The hydro-geologic stages in the Biyang Depression, Henan Province, were defined and factors controlling the evolution of the hydrodynamic field in this area were analyzed. The evolution of the paleo-hydrodynamic field was studied by using the method of sedimentary-water-head and the changing patterns of the present hydrodynamic field as determined from measured pressure data. The results show that the evolution of the hydrodynamic field is one of inheritance and that it controls hydrocarbon accumulation. The deposition center in the southeast of the depression is always a high-value zone for water-head and a dynamic- source zone of the hydrodynamic field. The slope zone in the northwest of the depression is always a low-value zone for water-head and is the main discharge area for groundwater; this is the hydrocarbon accumulation zone. Hydrocarbon accumulation is controlled by the hydrodynamic field. The reservoir shows a ring-shaped horizontal pattern. Accumulation occurs in a pressure equilibrium zone at the frontal surface between sedimentary water and infiltrating water. The hydrocarbon accumulations occur in two vertically different discharge units, Eh31 and Eh32, under the action of overpressure.展开更多
Based on the merged 3 D seismic data, well logging, formation testing, analysis and testing data, the structural evolution, sedimentary reservoirs, thermal evolution of source rocks were investigated of Paleogene Kong...Based on the merged 3 D seismic data, well logging, formation testing, analysis and testing data, the structural evolution, sedimentary reservoirs, thermal evolution of source rocks were investigated of Paleogene Kongdian Formation in the trough area of Cangdong sag, Bohai Bay Basin. A conventional-unconventional hydrocarbon accumulation pattern in the trough area of rifted basin was revealed. The reservoir forming elements in the trough area of Cangdong sag have a zonation feature in terms of reservoirs and source rocks. There are two types of reservoir forming models, primary trough and reformed trough. The formation and evolution of trough controlled the orderly distribution of conventional oil to unconventional oil in the trough. Particularly, structural reservoirs occur in the upper part of the trough, stratigraphic-lithologic reservoirs are likely to form in the delta front deposits at the outer ring of trough, the middle ring transitional belt is the favorable site for tight oil reservoirs, while the fine grain deposits zone in the inner ring is shale oil and gas exploration area. The study has pointed out the new domains and directions for searching reserves in the secondary exploration of mature oilfields.展开更多
The PL 19e3 Oilfield is the only super-large monolithic oilfield with oil and gas reserves up to 1×10^(9) t in the Bohai Bay Basin,and it has been successfully developed.Exploration and development practices have...The PL 19e3 Oilfield is the only super-large monolithic oilfield with oil and gas reserves up to 1×10^(9) t in the Bohai Bay Basin,and it has been successfully developed.Exploration and development practices have provided abundant data for analyzing formation conditions of this super-large oilfield.On the basis of the exploration and development history,fundamental reservoir features,and with available geological,geophysical and test data,the hydrocarbon accumulation conditions and key exploration&development technologies of the PL 19e3 Oilfield were discussed.The key conditions for forming the super-large Neogene oilfield include four aspects.Firstly,the oilfield is located at the high position of the uplift that contacts the brachy-axis of the multi-ridge slope in the biggest hydrocarbon-rich sag in the Bohai Bay Basin,thus it has sufficient hydrocarbon source and extremely superior hydrocarbon migration condition.Secondly,the large-scale torsional anticlines which formed in the Neogene under the control of the Tanlu strike-slipping movement provide sufficient storage spaces for oil and gas preservation.Thirdly,the“multiple sets of composite reservoir-caprock assemblages”developing in the special shallow-water delta further contributes greatly to the effective storage space for oil and gas preservation.Fourthly,due to the coupling of the uplift and strike slip in the neotectonic period,extensive faulting activities constantly released the pressure while the late period massive hydrocarbon expulsion of the Bozhong took place at the same time,which assures the constant and intense charging of oil and gas.The super-large PL 19e3 Oilfield was controlled by the coupling effects of all those special geologic factors.In view of this oilfield's features(e.g.violently reformation caused by strike slip,and the special sedimentary environment of shallow-water delta),some key practical technologies for exploration and development have been developed.Such technologies include:the special prestack depth migration processing for gas cloud zones,the prediction of thin interbed reservoirs based on high-precision inversion of geologic model,the reservoir description for the shallow-water braided river delta,the quantitative description for remaining oil in the commingled oil reservoirs with wide well spacing and long well interval,and the well pattern adjustment for formations during high water cut period in the complex fluvial-facies oilfields.展开更多
基金funded by the National Natural Science Foundation of China(No.42072149).
文摘Transfer zones are structural areas of faults interactions where fault motion or displacement can be transferred from one fault to another, regional strain maintains laterally constant. Transfer zones are widely developed in rift basins and have significance on hydrocarbon accumulation. In this review article, we attempt to summarize recent advances on the types, distance-displacement curves, evolutionary stages and controlling factors of transfer zones in rift basins and their effects on sedimentary systems, reservoir properties, trap formation and hydrocarbon migration. The formation of transfer zones is genetically related to the segmented growth of normal faults. Depending on the degree of interaction between these normal faults, transfer zones in rift basins could be divided into two types: soft-linked and hard-linked, which are further subdivided into transfer slope, oblique anticline, horst and transfer fault based on the combination patterns of normal faults. In general, the development of transfer zones experiences several stages including isolated normal faulting, transfer slope forming, complicating and breaking. During the interaction and growth of segmented normal faults, stress-strain and spatial array of faults, pre-existing basement structures, and mechanical conditions of rocks have a great influence on the location and development processes of transfer zones. A transfer zone is commonly considered as a pathway for conveying sediments from provenance to basin, and it hence exerts an essential control on the distribution of sandbodies. In addition, transfer zone is the area where stresses are concentrated, which facilitates the formation of various types of structural traps, and it is also a favorable conduit for hydrocarbon migration. Consequently, there exists great hydrocarbon potentials in transfer zones to which more attention should be given.
基金Supported by the PetroChina Oil&Gas and New Energy Company Project(2022KT0405)PetroChina Science and Technology Major Project(2021DJ0605)Basic and Prospective Science and Technology Project of Petrochina Science and Technology Management Department(2021DJ0404).
文摘According to the latest drilling and the analysis of the burial history,source rock evolution history and hydrocarbon accumulation history,the sub-source hydrocarbon accumulation characteristics of the Permian reservoirs in the Jinan Sag,eastern Junggar Basin,are clarified,and the hydrocarbon accumulation model of these reservoirs is established.The results are obtained in four aspects.First,the main body of the thick salified lake basin source rocks in the Lucaogou Formation has reached the mature stage with abundant resource base.Large-scale reservoirs are developed in the Jingjingzigou,Wutonggou and Lucaogou formations.Vertically,there are multiple sets of good regional seals,the source-reservoir-caprock assemblage is good,and there are three reservoir-forming assemblages:sub-source,intra-source and above-source.Second,dissolution,hydrocarbon charging and pore-preserving effect,and presence of chlorite film effectively increase the sub-source pore space.Oil charging is earlier than the time when the reservoir becomes densified,which improves the efficiency of hydrocarbon accumulation.Third,buoyancy and source-reservoir pressure difference together constitute the driving force of oil charging,and the micro-faults within the formation give the advantage of"source-reservoir lateral docking"under the source rock.Microfractures can be critical channels for efficient seepage and continuous charging of oil in different periods.Fourth,the Jingjingzigou Formation experienced three periods of oil accumulation in the Middle-Late Permian,Middle-Late Jurassic and Late Neogene,with the characteristics of long-distance migration and accumulation in early stage,mixed charging and accumulation in middle stage and short-distance migration and high-position accumulation in late stage.The discovery and theoretical understanding of the Permian reservoirs in the Jinan Sag reveal that the thrust belt has good conditions for forming large reservoirs,and it is promising for exploration.The study results are of guidance and reference significance for oil and gas exploration in the Jinan Sag and other geologically similar areas.
基金supported by the National 973 Basic Research Program (Grant No.2006CB202308)the Major National Science & Technology Program (2008ZX05008-004-012)
文摘Understanding hydrocarbon migration and accumulation mechanisms is one of the key scientif ic problems that should be solved for effective hydrocarbon exploration in the superimposed basins developed in northwest China. The northwest striking No.1 slope break zone, which is a representative of superimposed basins in the Tarim Basin, can be divided into five parts due to the intersection of the northeast strike-slip faults. Controlled by the tectonic framework, the types and properties of reservoirs and the hydrocarbon compositions can also be divided into five parts from east to west. Anomalies of all the parameters were found on the fault intersection zone and weakened up-dip along the structural ridge away from it. Thus, it can be inferred that the intersection zone is the hydrocarbon charging position. This new conclusion differs greatly from the traditional viewpoint, which believes that the hydrocarbon migrates and accumulates along the whole plane of the No.1 slope break zone. The viewpoint is further supported by the evidence from the theory of main pathway systems, obvious improvement of the reservoir quality (2-3 orders of magnitude at the intersection zone) and the formation mechanisms of the fault intersection zone. Differential hydrocarbon migration and entrapment exists in and around the strike- slip faults. This is controlled by the internal structure of faults. It is concluded that the more complicated the fault structure is, the more significant the effects will be. If there is a deformation band, it will hinder the cross fault migration due to the common feature of two to four orders of magnitude reduction in permeability. Otherwise, hydrocarbons tend to accumulate in the up-dip structure under the control of buoyancy. Further research on the internal fault structure should be emphasized.
基金Supported by the China National Science and Technology Major Project(2017ZX05008-001,2011ZX05003-003)
文摘The development, evolution and formation mechanism of faults and their control on the migration and accumulation of Mesozoic oil and gas in the middle-shallow layers of the slope zone of Mahu sag were studied by the interpretation of seismic and drilling data. Two types of faults, normal and strike-slip, are developed in the middle-shallow layers of the slope zone of the Mahu sag and they are mostly active in the Yanshanian period. They are divided into four grade faults: The grade I strike-slip faults with NWW to near EW direction are related to the left-lateral transpressive fault zones in the northwest of Junggar Basin since the end of the Triassic. The grade II faults with NE to NNE direction are the normal faults located at the junction of the fault zone and the slope zone, and their formation is related to the extension at the top of the nose-like structures in the fault zone. The grade III faults, which are also the normal faults, are the result of the extension at the top of the lower uplifts in the slope zone and differential compaction. The grade IV faults with NE direction are normal faults, which may be related to the extension environment at the tip of the lower uplifts. Faults not only are the channel for the vertical migration of oil and gas, but also control the oil-gas accumulation. There are two types of oil-gas reservoirs in the middle-shallow layers of slope zone of Mahu sag: fault block reservoirs and fault-lithologic reservoirs. They have large traps and promising exploration potential.
基金support for this work, provided by the SINOPEC foundation (CW800-07-ZS-165-01)doctor’s foundation of Henan Polytechnic University (648167)
文摘The hydro-geologic stages in the Biyang Depression, Henan Province, were defined and factors controlling the evolution of the hydrodynamic field in this area were analyzed. The evolution of the paleo-hydrodynamic field was studied by using the method of sedimentary-water-head and the changing patterns of the present hydrodynamic field as determined from measured pressure data. The results show that the evolution of the hydrodynamic field is one of inheritance and that it controls hydrocarbon accumulation. The deposition center in the southeast of the depression is always a high-value zone for water-head and a dynamic- source zone of the hydrodynamic field. The slope zone in the northwest of the depression is always a low-value zone for water-head and is the main discharge area for groundwater; this is the hydrocarbon accumulation zone. Hydrocarbon accumulation is controlled by the hydrodynamic field. The reservoir shows a ring-shaped horizontal pattern. Accumulation occurs in a pressure equilibrium zone at the frontal surface between sedimentary water and infiltrating water. The hydrocarbon accumulations occur in two vertically different discharge units, Eh31 and Eh32, under the action of overpressure.
基金Supported by the China National Science and Technology Major Project(2016ZX05006-005)PetroChina Science and Technology Major Project(2018E-11)
文摘Based on the merged 3 D seismic data, well logging, formation testing, analysis and testing data, the structural evolution, sedimentary reservoirs, thermal evolution of source rocks were investigated of Paleogene Kongdian Formation in the trough area of Cangdong sag, Bohai Bay Basin. A conventional-unconventional hydrocarbon accumulation pattern in the trough area of rifted basin was revealed. The reservoir forming elements in the trough area of Cangdong sag have a zonation feature in terms of reservoirs and source rocks. There are two types of reservoir forming models, primary trough and reformed trough. The formation and evolution of trough controlled the orderly distribution of conventional oil to unconventional oil in the trough. Particularly, structural reservoirs occur in the upper part of the trough, stratigraphic-lithologic reservoirs are likely to form in the delta front deposits at the outer ring of trough, the middle ring transitional belt is the favorable site for tight oil reservoirs, while the fine grain deposits zone in the inner ring is shale oil and gas exploration area. The study has pointed out the new domains and directions for searching reserves in the secondary exploration of mature oilfields.
基金The work was supported by the National Science and Technology Major Project of China(No.2016ZX05024-003).
文摘The PL 19e3 Oilfield is the only super-large monolithic oilfield with oil and gas reserves up to 1×10^(9) t in the Bohai Bay Basin,and it has been successfully developed.Exploration and development practices have provided abundant data for analyzing formation conditions of this super-large oilfield.On the basis of the exploration and development history,fundamental reservoir features,and with available geological,geophysical and test data,the hydrocarbon accumulation conditions and key exploration&development technologies of the PL 19e3 Oilfield were discussed.The key conditions for forming the super-large Neogene oilfield include four aspects.Firstly,the oilfield is located at the high position of the uplift that contacts the brachy-axis of the multi-ridge slope in the biggest hydrocarbon-rich sag in the Bohai Bay Basin,thus it has sufficient hydrocarbon source and extremely superior hydrocarbon migration condition.Secondly,the large-scale torsional anticlines which formed in the Neogene under the control of the Tanlu strike-slipping movement provide sufficient storage spaces for oil and gas preservation.Thirdly,the“multiple sets of composite reservoir-caprock assemblages”developing in the special shallow-water delta further contributes greatly to the effective storage space for oil and gas preservation.Fourthly,due to the coupling of the uplift and strike slip in the neotectonic period,extensive faulting activities constantly released the pressure while the late period massive hydrocarbon expulsion of the Bozhong took place at the same time,which assures the constant and intense charging of oil and gas.The super-large PL 19e3 Oilfield was controlled by the coupling effects of all those special geologic factors.In view of this oilfield's features(e.g.violently reformation caused by strike slip,and the special sedimentary environment of shallow-water delta),some key practical technologies for exploration and development have been developed.Such technologies include:the special prestack depth migration processing for gas cloud zones,the prediction of thin interbed reservoirs based on high-precision inversion of geologic model,the reservoir description for the shallow-water braided river delta,the quantitative description for remaining oil in the commingled oil reservoirs with wide well spacing and long well interval,and the well pattern adjustment for formations during high water cut period in the complex fluvial-facies oilfields.