Based on the situation and progress of marine oil/gas exploration in the Sichuan Basin,SW China,the whole petroleum system is divided for marine carbonate rocks of the basin according to the combinations of hydrocarbo...Based on the situation and progress of marine oil/gas exploration in the Sichuan Basin,SW China,the whole petroleum system is divided for marine carbonate rocks of the basin according to the combinations of hydrocarbon accumulation elements,especially the source rock.The hydrocarbon accumulation characteristics of each whole petroleum system are analyzed,the patterns of integrated conventional and unconventional hydrocarbon accumulation are summarized,and the favorable exploration targets are proposed.Under the control of multiple extensional-convergent tectonic cycles,the marine carbonate rocks of the Sichuan Basin contain three sets of regional source rocks and three sets of regional cap rocks,and can be divided into the Cambrian,Silurian and Permian whole petroleum systems.These whole petroleum systems present mainly independent hydrocarbon accumulation,containing natural gas of affinity individually.Locally,large fault zones run through multiple whole petroleum systems,forming a fault-controlled complex whole petroleum system.The hydrocarbon accumulation sequence of continental shelf facies shale gas accumulation,marginal platform facies-controlled gas reservoirs,and intra-platform fault-and facies-controlled gas reservoirs is common in the whole petroleum system,with a stereoscopic accumulation and orderly distribution pattern.High-quality source rock is fundamental to the formation of large gas fields,and natural gas in a whole petroleum system is generally enriched near and within the source rocks.The development and maintenance of large-scale reservoirs are essential for natural gas enrichment,multiple sources,oil and gas transformation,and dynamic adjustment are the characteristics of marine petroleum accumulation,and good preservation conditions are critical to natural gas accumulation.Large-scale marginal-platform reef-bank facies zones,deep shale gas,and large-scale lithological complexes related to source-connected faults are future marine hydrocarbon exploration targets in the Sichuan Basin.展开更多
Based on the oil and gas exploration practice in the Songliao Basin,combined with the latest exploration and development data such as seismic,well logging and geochemistry,the basic geological conditions,oil and gas t...Based on the oil and gas exploration practice in the Songliao Basin,combined with the latest exploration and development data such as seismic,well logging and geochemistry,the basic geological conditions,oil and gas types and distribution characteristics,reservoir-forming dynamics,source-reservoir relationship and hydrocarbon accumulation model of the whole petroleum system in shallow and medium strata in the northern part of Songliao Basin are systematically studied.The shallow-medium strata in northern Songliao Basin have the conditions for the formation of whole petroleum system,with sufficient oil and gas sources,diverse reservoir types and well-developed transport system,forming a whole petroleum system centered on the source rocks of the Cretaceous Qingshankou Formation.Different types of oil and gas resources in the whole petroleum system are correlated with each other in terms of depositional system,lithologic association and physical property changes,and they,to a certain extent,have created the spatial framework with orderly symbiosis of shallow-medium conventional oil reservoirs,tight oil reservoirs and shale oil reservoirs in northern Songliao Basin.Vertically,the resources are endowed as conventional oil above source,shale oil/tight oil within source,and tight oil below source.Horizontally,conventional oil,tight oil,interlayer-type shale oil,and pure shale-type shale oil are developed in an orderly way,from the margin of the basin to the center of the depression.Three hydrocarbon accumulation models are recognized for the whole petroleum system in northern Songliao Basin,namely,buoyancy-driven charging of conventional oil above source,retention of shale oil within source,and pressure differential-driven charging of tight oil below source.展开更多
As petroleum exploration advances and as most of the oil-gas reservoirs in shallow layers have been explored, petroleum exploration starts to move toward deep basins, which has become an inevitable choice. In this pap...As petroleum exploration advances and as most of the oil-gas reservoirs in shallow layers have been explored, petroleum exploration starts to move toward deep basins, which has become an inevitable choice. In this paper, the petroleum geology features and research progress on oil-gas reservoirs in deep petroliferous basins across the world are characterized by using the latest results of worldwide deep petroleum exploration. Research has demonstrated that the deep petroleum shows ten major geological features. (1) While oil-gas reservoirs have been discovered in many different types of deep petroliferous basins, most have been discovered in low heat flux deep basins. (2) Many types of petroliferous traps are developed in deep basins, and tight oil-gas reservoirs in deep basin traps are arousing increasing attention. (3) Deep petroleum normally has more natural gas than liquid oil, and the natural gas ratio increases with the burial depth. (4) The residual organic matter in deep source rocks reduces but the hydrocarbon expulsion rate and efficiency increase with the burial depth. (5) There are many types of rocks in deep hydrocarbon reservoirs, and most are clastic rocks and carbonates. (6) The age of deep hydrocarbon reservoirs is widely different, but those recently discovered are pre- dominantly Paleogene and Upper Paleozoic. (7) The porosity and permeability of deep hydrocarbon reservoirs differ widely, but they vary in a regular way with lithology and burial depth. (8) The temperatures of deep oil-gas reservoirs are widely different, but they typically vary with the burial depth and basin geothermal gradient. (9) The pressures of deep oil-gas reservoirs differ significantly, but they typically vary with burial depth, genesis, and evolu- tion period. (10) Deep oil-gas reservoirs may exist with or without a cap, and those without a cap are typically of unconventional genesis. Over the past decade, six major steps have been made in the understanding of deep hydrocarbon reservoir formation. (1) Deep petroleum in petroliferous basins has multiple sources and many dif- ferent genetic mechanisms. (2) There are high-porosity, high-permeability reservoirs in deep basins, the formation of which is associated with tectonic events and subsurface fluid movement. (3) Capillary pressure differences inside and outside the target reservoir are the principal driving force of hydrocarbon enrichment in deep basins. (4) There are three dynamic boundaries for deep oil-gas reservoirs; a buoyancy-controlled threshold, hydrocarbon accumulation limits, and the upper limit of hydrocarbon generation. (5) The formation and distribution of deep hydrocarbon res- ervoirs are controlled by free, limited, and bound fluid dynamic fields. And (6) tight conventional, tight deep, tight superimposed, and related reconstructed hydrocarbon reservoirs formed in deep-limited fluid dynamic fields have great resource potential and vast scope for exploration. Compared with middle-shallow strata, the petroleum geology and accumulation in deep basins are more complex, which overlap the feature of basin evolution in different stages. We recommend that further study should pay more attention to four aspects: (1) identification of deep petroleum sources and evaluation of their relative contributions; (2) preservation conditions and genetic mechanisms of deep high-quality reservoirs with high permeability and high porosity; (3) facies feature and transformation of deep petroleum and their potential distribution; and (4) economic feasibility evaluation of deep tight petroleum exploration and development.展开更多
Objective The natural gas exploration of the Sinian reservoirs in the central Sichuan Basin has made a significant breakthrough in recent years, and has thus attracted much attention among geologists. The Sichuan Bas...Objective The natural gas exploration of the Sinian reservoirs in the central Sichuan Basin has made a significant breakthrough in recent years, and has thus attracted much attention among geologists. The Sichuan Basin is known to have complicated geological settings, which has experienced multiple stages of tectonic evolution, fluid charging and hydrocarbon accumulation. This research aims to determine the geochemical characteristics of each stage of fluids, the features and time interval of fluid activity in different geologic periods, and further to restore the critical period and geological age of the hydrocarbon accumulation.展开更多
The study area Caofeidian 18-1/2 structure is located in the Shadongnan structural belt at the southeast subduction end of the Shaleitian salient in the western Bohai Sea. The characteristics of reservoirs and fluid i...The study area Caofeidian 18-1/2 structure is located in the Shadongnan structural belt at the southeast subduction end of the Shaleitian salient in the western Bohai Sea. The characteristics of reservoirs and fluid inclusions from 13 core samples near the buried hills in the study area are studied,and regional geology and conditions for reservoir formation are analyzed to reveal the characteristics and the processes of reservoir formation. Phase I oil and gas inclusions are mainly developed,and the abundance of oil and gas inclusions in this period is high( GOI is about 15%). The homogenization temperature of the hydrocarbon-containing brine inclusions accompanying them is mainly 90-120 ℃ . The simulation results of burial history and thermal history show that the main charging period of oil and gas is the present Himalayan tectonic movement period since 8 Ma,and mainly through unconformities,faults,and drainage systems,they are migrated and accumulated into fault anticline traps of Dongying Formation mudstone( E_d).展开更多
By using the latest geological,seismic,drilling and logging data,this article studies the basic conditions for the formation of the total petroleum system and the orderly coexisting characteristics and accumulation mo...By using the latest geological,seismic,drilling and logging data,this article studies the basic conditions for the formation of the total petroleum system and the orderly coexisting characteristics and accumulation models of conventional&unconventional reservoirs in the Lower Permian Fengcheng Formation in the Junggar Basin.Controlled by thermal evolution,hydrocarbon generation and expulsion process of the high-quality source rocks in alkaline lake as well as the characteristics of multi-type reservoirs(conglomerate,sandstone,dolomite and shale),conventional structure-lithologic reservoirs and tight oil and shale oil reservoirs controlled by source-reservoir structure have been formed.On the plane,mature conventional reservoirs,medium-high mature tight oil,and medium-high mature shale oil reservoirs coexist orderly from the slope area around Mahu sag to the sag.Based on the orderly coexisting characteristics of conventional and unconventional reservoirs in the Fengcheng Formation,it is clear that oil and gas in the Fengcheng Formation accumulate continuously over a large area in three accumulation models:integrated source-reservoir,source-reservoir in close contact,and separated source-reservoir model.The three accumulation models differ in relationship between source-reservoir structure,reservoir lithology and spatial distribution,hydrocarbon migration,oil and gas type.It is pointed out that the conventional&unconventional oil and gas should be explored and developed as a whole to achieve an overall breakthrough of the total petroleum system.This study is expected to enrich the geological theory of oil and gas enrichment in continental basins and to provide an analogy for exploration and research in other hydrocarbon-rich sags.展开更多
Based on the results of fluid inclusion study(microscopic characteristics,homogenization temperatures and grains with oil inclusions),the pool-forming time of the Nanbaxian and Mabei 1 oilfields in northern Qaidam Bas...Based on the results of fluid inclusion study(microscopic characteristics,homogenization temperatures and grains with oil inclusions),the pool-forming time of the Nanbaxian and Mabei 1 oilfields in northern Qaidam Basin was discussed in this paper.Fluid inclusions in northern Qaidam Basin are relatively abundant,including aqueous inclusions and hydrocarbon inclusions.These inclusions are small(5-10 μm),and mainly distributed in quartz fissures,overgrowths and cementations.The abundances of grains with oil inclusions(GOI) are commonly low.The GOI values of most samples are between 2.0%-10.5%,and those of about 40 percent of total samples exceed 5%.The homogenization temperatures of fluid inclusions in different samples are markedly dissimilar,indicating that these inclusions were formed in different periods.According to the measured homogenization temperatures of fluid inclusions and in combination with burial history and thermal evolution history,the Nanbaxian and Mabei 1 oilfields are deduced,which have experienced two hydrocarbon charging periods,with the former of N1-N21 and N22-N23,and the latter of N1 and N1 end-N2,respectively.展开更多
This paper expounds the basic principles and structures of the whole petroleum system to reveal the pattern of conventional oil/gas-tight oil/gas-shale oil/gas sequential accumulation and the hydrocarbon accumulation ...This paper expounds the basic principles and structures of the whole petroleum system to reveal the pattern of conventional oil/gas-tight oil/gas-shale oil/gas sequential accumulation and the hydrocarbon accumulation models and mechanisms of the whole petroleum system.It delineates the geological model,flow model,and production mechanism of shale and tight reservoirs,and proposes future research orientations.The main structure of the whole petroleum system includes three fluid dynamic fields,three types of oil and gas reservoirs/resources,and two types of reservoir-forming processes.Conventional oil/gas,tight oil/gas,and shale oil/gas are orderly in generation time and spatial distribution,and sequentially rational in genetic mechanism,showing the pattern of sequential accumulation.The whole petroleum system involves two categories of hydrocarbon accumulation models:hydrocarbon accumulation in the detrital basin and hydrocarbon accumulation in the carbonate basin/formation.The accumulation of unconventional oil/gas is self-containment,which is microscopically driven by the intermolecular force(van der Waals force).The unconventional oil/gas production has proved that the geological model,flow model,and production mechanism of shale and tight reservoirs represent a new and complex field that needs further study.Shale oil/gas must be the most important resource replacement for oil and gas resources of China.Future research efforts include:(1)the characteristics of the whole petroleum system in carbonate basins and the source-reservoir coupling patterns in the evolution of composite basins;(2)flow mechanisms in migration,accumulation,and production of shale oil/gas and tight oil/gas;(3)geological characteristics and enrichment of deep and ultra-deep shale oil/gas,tight oil/gas and coalbed methane;(4)resource evaluation and new generation of basin simulation technology of the whole petroleum system;(5)research on earth system-earth organic rock and fossil fuel system-whole petroleum system.展开更多
Several international oil companies had conducted petroleum exploration, but failed to make any commercially viable discoveries in the Doseo Basin for over 30 years. In this article, an integrated analysis, based on t...Several international oil companies had conducted petroleum exploration, but failed to make any commercially viable discoveries in the Doseo Basin for over 30 years. In this article, an integrated analysis, based on the latest seismic and drilling data combined with exploration practice and tectonic, sedimentary as well as petroleum-geological characteristics of the basin, has been conducted with the aim to disclose the key factors of hydrocarbon accumulation and enrichment and then to find the potential petroleum plays. The Doseo Basin in Chad is a Meso-Cenozoic lacustrine rift basin developed on the Precambrian crystalline basement in the Central African Shear Zone. It is a half graben rift controlled by the strike-slip fault at the northern boundary, and can be divided into two sub-basins, an uplift and a slope. The basin experienced two rifting periods in the Cretaceous and was strongly inverted with the erosion thickness of 800–1000 m during the Eocene, and then entered the depression and extinction period. Structurally, a large number of normal faults and strike-slip faults are identified in the basin, and the boundary faults are inverted faults with normal at first. The main structural styles include inverted anticlines, fault noses, complex fault-blocks and flower structures. The Lower Cretaceous is the main sedimentary strata, which are divided into the Mangara Group, Kedeni, Doba and Koumra Formations from bottom to up. Two transgressive-regressive cycles developed in the Lower Cretaceous indicates with mainly lacustrine, fluvial, delta, braided-delta, fan-delta sandstone and mudstone. The effective source rock in the basin is the deep-lacustrine mudstone of the Lower Cretaceous containing the type Ⅰ and type Ⅱ;organic matters. Furthermore, Inverted anticlines and fault-complicated blocks comprise the main trap types and the Kedeni Uplift is the most favorable play, followed by the Northern Steep Slope and Southern Gentle Slope. Lateral sealing capacity of faults controls the hydrocarbon abundance.展开更多
Based on the oil and gas exploration in western depression of the Qaidam Basin,NW China,combined with the geochemical,seismic,logging and drilling data,the basic geological conditions,oil and gas distribution characte...Based on the oil and gas exploration in western depression of the Qaidam Basin,NW China,combined with the geochemical,seismic,logging and drilling data,the basic geological conditions,oil and gas distribution characteristics,reservoir-forming dynamics,and hydrocarbon accumulation model of the Paleogene whole petroleum system(WPS)in the western depression of the Qaidam Basin are systematically studied.A globally unique ultra-thick mountain-style WPS is found in the western depression of the Qaidam Basin.Around the source rocks of the upper member of the Paleogene Lower Ganchaigou Formation,the structural reservoir,lithological reservoir,shale oil and shale gas are laterally distributed in an orderly manner and vertically overlapped from the edge to the central part of the lake basin.The Paleogene WPS in the western depression of the Qaidam Basin is believed unique in three aspects.First,the source rocks with low organic matter abundance are characterized by low carbon and rich hydrogen,showing a strong hydrocarbon generating capacity per unit mass of organic carbon.Second,the saline lake basinal deposits are ultra-thick,with mixed deposits dominating the center of the depression,and strong vertical and lateral heterogeneity of lithofacies and storage spaces.Third,the strong transformation induced by strike-slip compression during the Himalayan resulted in the heterogeneous enrichment of oil and gas in the mountain-style WPS.As a result of the coordinated evolution of source-reservoir-caprock assemblage and conducting system,the Paleogene WPS has the characteristics of“whole process”hydrocarbon generation of source rocks which are low-carbon and hydrogen-rich,“whole depression”ultra-thick reservoir sedimentation,“all direction”hydrocarbon adjustment by strike-slip compressional fault,and“whole succession”distribution of conventional and unconventional oil and gas.Due to the severe Himalayan tectonic movement,the western depression of the Qaidam Basin evolved from depression to uplift.Shale oil is widely distributed in the central lacustrine basin.In the sedimentary system thicker than 2000 m,oil and gas are continuous in the laminated limy-dolomites within the source rocks and the alga limestones neighboring the source kitchen,with intercrystalline pores,lamina fractures in dolomites and fault-dissolution bodies serving as the effective storage space.All these findings are helpful to supplement and expand the WPS theory in the continental lake basins in China,and provide theoretical guidance and technical support for oil and gas exploration in the Qaidam Basin.展开更多
The Bozhong19-6(BZ19-6)condensate gas reservoirs,located in the southwestern Bozhong sub-basin,Bohai Bay Basin,China,were paleo-oil reservoirs in the geological past and have undergone at least three successive hydroc...The Bozhong19-6(BZ19-6)condensate gas reservoirs,located in the southwestern Bozhong sub-basin,Bohai Bay Basin,China,were paleo-oil reservoirs in the geological past and have undergone at least three successive hydrocarbon charging events.The hydrocarbon migration and accumulation process of“early oil and late gas”has occurred in the current reservoirs.At the end of the sedimentation of the Guantao Formation(N_(1)g,∼12 Ma),the reservoirs began to fill with first stage low-moderate mature crude oil.At the late stage of the Lower Minghuazhen Formation(N_(1)ml)(∼6.7 Ma),the reservoirs were largely charged with second stage high mature crude oil.Since the deposition of the upper Minghuazhen Formation(N_(2)m^(u),∼5.1 Ma),the paleo-oil reservoirs were transformed into shallow Neogene reservoirs due to the reactivation of basement faults.From the late stage of the N_(2)m^(u)to the present day(∼2.8–0 Ma),the reservoirs were rapidly filled by natural gas within a short period.In addition,analysis of the formation of the reservoir bitumen and the conspicuous loss of the lower molecular weight n-alkanes in the crude oil reveal that the injection of a large amount of gas in the late stage caused gas flushing of the early charged oil.展开更多
In northwestern Ordos Basin, the Triassic reservoir Chang 9 has favorable reservoir forming conditions, extensive reservoir development, and huge potential for oil exploration and exploitation. Studying the main contr...In northwestern Ordos Basin, the Triassic reservoir Chang 9 has favorable reservoir forming conditions, extensive reservoir development, and huge potential for oil exploration and exploitation. Studying the main controlling factors and accumulation model of Chang 9 reservoir in this area can provide a basis for the production targets, and assist in formulating reasonable development technology policy. In this paper, to explore and summarize the hydrocarbon accumulation model, the Chang 9 reservoir were analyzed from the aspects of oil source, fracture, oil migration, structure, lithology and reservoir physical properties for the main controlling factors in this area. Organic geochemical and geological comprehensive analysis that the oil-source of the Chang 9 reservoir in the northwest of Ordos Basin is derived from Chang 7 hydrocarbon source rocks. The fractures provide a sound channel for the "vertical multi-point filling" of the oil source from Chang 7 to Chang 9. The crude oil migrates vertically from Chang 7 to Chang 9, then expands horizontally to form a reservoir. Structures play an important role in controlling the distribution of reservoirs, the control by sand in small layer and physical property is also obvious. This paper creatively establishes the reservoir accumulation model of Chang 9 in northwest of Ordos Basin, which is characterized by Vertical multi-point filling, horizontal expansion becomes oil pool. It reveals the genetic mechanism of the development of Chang 9 multi-reservoir in the study area, which provides guidance for exploration and evaluation deployment.展开更多
基金Supported by the National Natural Science Foundation of China(42090022)。
文摘Based on the situation and progress of marine oil/gas exploration in the Sichuan Basin,SW China,the whole petroleum system is divided for marine carbonate rocks of the basin according to the combinations of hydrocarbon accumulation elements,especially the source rock.The hydrocarbon accumulation characteristics of each whole petroleum system are analyzed,the patterns of integrated conventional and unconventional hydrocarbon accumulation are summarized,and the favorable exploration targets are proposed.Under the control of multiple extensional-convergent tectonic cycles,the marine carbonate rocks of the Sichuan Basin contain three sets of regional source rocks and three sets of regional cap rocks,and can be divided into the Cambrian,Silurian and Permian whole petroleum systems.These whole petroleum systems present mainly independent hydrocarbon accumulation,containing natural gas of affinity individually.Locally,large fault zones run through multiple whole petroleum systems,forming a fault-controlled complex whole petroleum system.The hydrocarbon accumulation sequence of continental shelf facies shale gas accumulation,marginal platform facies-controlled gas reservoirs,and intra-platform fault-and facies-controlled gas reservoirs is common in the whole petroleum system,with a stereoscopic accumulation and orderly distribution pattern.High-quality source rock is fundamental to the formation of large gas fields,and natural gas in a whole petroleum system is generally enriched near and within the source rocks.The development and maintenance of large-scale reservoirs are essential for natural gas enrichment,multiple sources,oil and gas transformation,and dynamic adjustment are the characteristics of marine petroleum accumulation,and good preservation conditions are critical to natural gas accumulation.Large-scale marginal-platform reef-bank facies zones,deep shale gas,and large-scale lithological complexes related to source-connected faults are future marine hydrocarbon exploration targets in the Sichuan Basin.
基金Supported by the PetroChina Major Science and Technology Project (2016E0201,2021ZZ10,2021DJ0101)。
文摘Based on the oil and gas exploration practice in the Songliao Basin,combined with the latest exploration and development data such as seismic,well logging and geochemistry,the basic geological conditions,oil and gas types and distribution characteristics,reservoir-forming dynamics,source-reservoir relationship and hydrocarbon accumulation model of the whole petroleum system in shallow and medium strata in the northern part of Songliao Basin are systematically studied.The shallow-medium strata in northern Songliao Basin have the conditions for the formation of whole petroleum system,with sufficient oil and gas sources,diverse reservoir types and well-developed transport system,forming a whole petroleum system centered on the source rocks of the Cretaceous Qingshankou Formation.Different types of oil and gas resources in the whole petroleum system are correlated with each other in terms of depositional system,lithologic association and physical property changes,and they,to a certain extent,have created the spatial framework with orderly symbiosis of shallow-medium conventional oil reservoirs,tight oil reservoirs and shale oil reservoirs in northern Songliao Basin.Vertically,the resources are endowed as conventional oil above source,shale oil/tight oil within source,and tight oil below source.Horizontally,conventional oil,tight oil,interlayer-type shale oil,and pure shale-type shale oil are developed in an orderly way,from the margin of the basin to the center of the depression.Three hydrocarbon accumulation models are recognized for the whole petroleum system in northern Songliao Basin,namely,buoyancy-driven charging of conventional oil above source,retention of shale oil within source,and pressure differential-driven charging of tight oil below source.
基金the National Basic Research Program of China (973 Program, 2011CB201100)‘‘Complex hydrocarbon accumulation mechanism and enrichmentregularities of deep superimposed basins in Western China’’ National Natural Science Foundation of China (U1262205) under the guidance of related department heads and experts
文摘As petroleum exploration advances and as most of the oil-gas reservoirs in shallow layers have been explored, petroleum exploration starts to move toward deep basins, which has become an inevitable choice. In this paper, the petroleum geology features and research progress on oil-gas reservoirs in deep petroliferous basins across the world are characterized by using the latest results of worldwide deep petroleum exploration. Research has demonstrated that the deep petroleum shows ten major geological features. (1) While oil-gas reservoirs have been discovered in many different types of deep petroliferous basins, most have been discovered in low heat flux deep basins. (2) Many types of petroliferous traps are developed in deep basins, and tight oil-gas reservoirs in deep basin traps are arousing increasing attention. (3) Deep petroleum normally has more natural gas than liquid oil, and the natural gas ratio increases with the burial depth. (4) The residual organic matter in deep source rocks reduces but the hydrocarbon expulsion rate and efficiency increase with the burial depth. (5) There are many types of rocks in deep hydrocarbon reservoirs, and most are clastic rocks and carbonates. (6) The age of deep hydrocarbon reservoirs is widely different, but those recently discovered are pre- dominantly Paleogene and Upper Paleozoic. (7) The porosity and permeability of deep hydrocarbon reservoirs differ widely, but they vary in a regular way with lithology and burial depth. (8) The temperatures of deep oil-gas reservoirs are widely different, but they typically vary with the burial depth and basin geothermal gradient. (9) The pressures of deep oil-gas reservoirs differ significantly, but they typically vary with burial depth, genesis, and evolu- tion period. (10) Deep oil-gas reservoirs may exist with or without a cap, and those without a cap are typically of unconventional genesis. Over the past decade, six major steps have been made in the understanding of deep hydrocarbon reservoir formation. (1) Deep petroleum in petroliferous basins has multiple sources and many dif- ferent genetic mechanisms. (2) There are high-porosity, high-permeability reservoirs in deep basins, the formation of which is associated with tectonic events and subsurface fluid movement. (3) Capillary pressure differences inside and outside the target reservoir are the principal driving force of hydrocarbon enrichment in deep basins. (4) There are three dynamic boundaries for deep oil-gas reservoirs; a buoyancy-controlled threshold, hydrocarbon accumulation limits, and the upper limit of hydrocarbon generation. (5) The formation and distribution of deep hydrocarbon res- ervoirs are controlled by free, limited, and bound fluid dynamic fields. And (6) tight conventional, tight deep, tight superimposed, and related reconstructed hydrocarbon reservoirs formed in deep-limited fluid dynamic fields have great resource potential and vast scope for exploration. Compared with middle-shallow strata, the petroleum geology and accumulation in deep basins are more complex, which overlap the feature of basin evolution in different stages. We recommend that further study should pay more attention to four aspects: (1) identification of deep petroleum sources and evaluation of their relative contributions; (2) preservation conditions and genetic mechanisms of deep high-quality reservoirs with high permeability and high porosity; (3) facies feature and transformation of deep petroleum and their potential distribution; and (4) economic feasibility evaluation of deep tight petroleum exploration and development.
基金supported by the Natural Science Foundation of China(grant No.41372141)
文摘Objective The natural gas exploration of the Sinian reservoirs in the central Sichuan Basin has made a significant breakthrough in recent years, and has thus attracted much attention among geologists. The Sichuan Basin is known to have complicated geological settings, which has experienced multiple stages of tectonic evolution, fluid charging and hydrocarbon accumulation. This research aims to determine the geochemical characteristics of each stage of fluids, the features and time interval of fluid activity in different geologic periods, and further to restore the critical period and geological age of the hydrocarbon accumulation.
基金Supported by Tianjin Branch of CNOOC(China)Co.,Ltd.(CCL2014TJX ZSS0870)。
文摘The study area Caofeidian 18-1/2 structure is located in the Shadongnan structural belt at the southeast subduction end of the Shaleitian salient in the western Bohai Sea. The characteristics of reservoirs and fluid inclusions from 13 core samples near the buried hills in the study area are studied,and regional geology and conditions for reservoir formation are analyzed to reveal the characteristics and the processes of reservoir formation. Phase I oil and gas inclusions are mainly developed,and the abundance of oil and gas inclusions in this period is high( GOI is about 15%). The homogenization temperature of the hydrocarbon-containing brine inclusions accompanying them is mainly 90-120 ℃ . The simulation results of burial history and thermal history show that the main charging period of oil and gas is the present Himalayan tectonic movement period since 8 Ma,and mainly through unconformities,faults,and drainage systems,they are migrated and accumulated into fault anticline traps of Dongying Formation mudstone( E_d).
基金Supported by the China National Science and Technology Major Project(2017ZX05001-004,2016ZX05046-006)Petrochina Science and Technology Major Project(2019E-2601,2019E-2602)。
文摘By using the latest geological,seismic,drilling and logging data,this article studies the basic conditions for the formation of the total petroleum system and the orderly coexisting characteristics and accumulation models of conventional&unconventional reservoirs in the Lower Permian Fengcheng Formation in the Junggar Basin.Controlled by thermal evolution,hydrocarbon generation and expulsion process of the high-quality source rocks in alkaline lake as well as the characteristics of multi-type reservoirs(conglomerate,sandstone,dolomite and shale),conventional structure-lithologic reservoirs and tight oil and shale oil reservoirs controlled by source-reservoir structure have been formed.On the plane,mature conventional reservoirs,medium-high mature tight oil,and medium-high mature shale oil reservoirs coexist orderly from the slope area around Mahu sag to the sag.Based on the orderly coexisting characteristics of conventional and unconventional reservoirs in the Fengcheng Formation,it is clear that oil and gas in the Fengcheng Formation accumulate continuously over a large area in three accumulation models:integrated source-reservoir,source-reservoir in close contact,and separated source-reservoir model.The three accumulation models differ in relationship between source-reservoir structure,reservoir lithology and spatial distribution,hydrocarbon migration,oil and gas type.It is pointed out that the conventional&unconventional oil and gas should be explored and developed as a whole to achieve an overall breakthrough of the total petroleum system.This study is expected to enrich the geological theory of oil and gas enrichment in continental basins and to provide an analogy for exploration and research in other hydrocarbon-rich sags.
基金supported by the National Largesized Oil and Gas fields Science and Technology Research Program (Grant No. 2008ZX05007-03)the National Natural Science Foundation of China (Grant No. 40572085)+2 种基金the New-century Excellent Talent Program of Ministry of Education (Grant No. NCET-06-0204)the Open Fund of State Key Laboratory of Petroleum Resource and Prospecting, China University of Petroleum (Grant No. 2009004)the Scientific Research Project of the Qinghai Oilfield Company (Grant No.QHKT/JL-03-013)
文摘Based on the results of fluid inclusion study(microscopic characteristics,homogenization temperatures and grains with oil inclusions),the pool-forming time of the Nanbaxian and Mabei 1 oilfields in northern Qaidam Basin was discussed in this paper.Fluid inclusions in northern Qaidam Basin are relatively abundant,including aqueous inclusions and hydrocarbon inclusions.These inclusions are small(5-10 μm),and mainly distributed in quartz fissures,overgrowths and cementations.The abundances of grains with oil inclusions(GOI) are commonly low.The GOI values of most samples are between 2.0%-10.5%,and those of about 40 percent of total samples exceed 5%.The homogenization temperatures of fluid inclusions in different samples are markedly dissimilar,indicating that these inclusions were formed in different periods.According to the measured homogenization temperatures of fluid inclusions and in combination with burial history and thermal evolution history,the Nanbaxian and Mabei 1 oilfields are deduced,which have experienced two hydrocarbon charging periods,with the former of N1-N21 and N22-N23,and the latter of N1 and N1 end-N2,respectively.
基金Supported by the National Natural Science Foundation of China(U22B6002)PetroChina Science Research and Technology Development Project(2021DJ0101)。
文摘This paper expounds the basic principles and structures of the whole petroleum system to reveal the pattern of conventional oil/gas-tight oil/gas-shale oil/gas sequential accumulation and the hydrocarbon accumulation models and mechanisms of the whole petroleum system.It delineates the geological model,flow model,and production mechanism of shale and tight reservoirs,and proposes future research orientations.The main structure of the whole petroleum system includes three fluid dynamic fields,three types of oil and gas reservoirs/resources,and two types of reservoir-forming processes.Conventional oil/gas,tight oil/gas,and shale oil/gas are orderly in generation time and spatial distribution,and sequentially rational in genetic mechanism,showing the pattern of sequential accumulation.The whole petroleum system involves two categories of hydrocarbon accumulation models:hydrocarbon accumulation in the detrital basin and hydrocarbon accumulation in the carbonate basin/formation.The accumulation of unconventional oil/gas is self-containment,which is microscopically driven by the intermolecular force(van der Waals force).The unconventional oil/gas production has proved that the geological model,flow model,and production mechanism of shale and tight reservoirs represent a new and complex field that needs further study.Shale oil/gas must be the most important resource replacement for oil and gas resources of China.Future research efforts include:(1)the characteristics of the whole petroleum system in carbonate basins and the source-reservoir coupling patterns in the evolution of composite basins;(2)flow mechanisms in migration,accumulation,and production of shale oil/gas and tight oil/gas;(3)geological characteristics and enrichment of deep and ultra-deep shale oil/gas,tight oil/gas and coalbed methane;(4)resource evaluation and new generation of basin simulation technology of the whole petroleum system;(5)research on earth system-earth organic rock and fossil fuel system-whole petroleum system.
基金Supported by the China National Science and Technology Major Project (2016ZX05029005)CNPC Scientific Research and Technology Development Project (2021DJ31)。
文摘Several international oil companies had conducted petroleum exploration, but failed to make any commercially viable discoveries in the Doseo Basin for over 30 years. In this article, an integrated analysis, based on the latest seismic and drilling data combined with exploration practice and tectonic, sedimentary as well as petroleum-geological characteristics of the basin, has been conducted with the aim to disclose the key factors of hydrocarbon accumulation and enrichment and then to find the potential petroleum plays. The Doseo Basin in Chad is a Meso-Cenozoic lacustrine rift basin developed on the Precambrian crystalline basement in the Central African Shear Zone. It is a half graben rift controlled by the strike-slip fault at the northern boundary, and can be divided into two sub-basins, an uplift and a slope. The basin experienced two rifting periods in the Cretaceous and was strongly inverted with the erosion thickness of 800–1000 m during the Eocene, and then entered the depression and extinction period. Structurally, a large number of normal faults and strike-slip faults are identified in the basin, and the boundary faults are inverted faults with normal at first. The main structural styles include inverted anticlines, fault noses, complex fault-blocks and flower structures. The Lower Cretaceous is the main sedimentary strata, which are divided into the Mangara Group, Kedeni, Doba and Koumra Formations from bottom to up. Two transgressive-regressive cycles developed in the Lower Cretaceous indicates with mainly lacustrine, fluvial, delta, braided-delta, fan-delta sandstone and mudstone. The effective source rock in the basin is the deep-lacustrine mudstone of the Lower Cretaceous containing the type Ⅰ and type Ⅱ;organic matters. Furthermore, Inverted anticlines and fault-complicated blocks comprise the main trap types and the Kedeni Uplift is the most favorable play, followed by the Northern Steep Slope and Southern Gentle Slope. Lateral sealing capacity of faults controls the hydrocarbon abundance.
基金Supported by the PetroChina Science and Technology Special Project(2021DQ0405,2023ZZ15)National Natural Science Foundation of China(42090025)。
文摘Based on the oil and gas exploration in western depression of the Qaidam Basin,NW China,combined with the geochemical,seismic,logging and drilling data,the basic geological conditions,oil and gas distribution characteristics,reservoir-forming dynamics,and hydrocarbon accumulation model of the Paleogene whole petroleum system(WPS)in the western depression of the Qaidam Basin are systematically studied.A globally unique ultra-thick mountain-style WPS is found in the western depression of the Qaidam Basin.Around the source rocks of the upper member of the Paleogene Lower Ganchaigou Formation,the structural reservoir,lithological reservoir,shale oil and shale gas are laterally distributed in an orderly manner and vertically overlapped from the edge to the central part of the lake basin.The Paleogene WPS in the western depression of the Qaidam Basin is believed unique in three aspects.First,the source rocks with low organic matter abundance are characterized by low carbon and rich hydrogen,showing a strong hydrocarbon generating capacity per unit mass of organic carbon.Second,the saline lake basinal deposits are ultra-thick,with mixed deposits dominating the center of the depression,and strong vertical and lateral heterogeneity of lithofacies and storage spaces.Third,the strong transformation induced by strike-slip compression during the Himalayan resulted in the heterogeneous enrichment of oil and gas in the mountain-style WPS.As a result of the coordinated evolution of source-reservoir-caprock assemblage and conducting system,the Paleogene WPS has the characteristics of“whole process”hydrocarbon generation of source rocks which are low-carbon and hydrogen-rich,“whole depression”ultra-thick reservoir sedimentation,“all direction”hydrocarbon adjustment by strike-slip compressional fault,and“whole succession”distribution of conventional and unconventional oil and gas.Due to the severe Himalayan tectonic movement,the western depression of the Qaidam Basin evolved from depression to uplift.Shale oil is widely distributed in the central lacustrine basin.In the sedimentary system thicker than 2000 m,oil and gas are continuous in the laminated limy-dolomites within the source rocks and the alga limestones neighboring the source kitchen,with intercrystalline pores,lamina fractures in dolomites and fault-dissolution bodies serving as the effective storage space.All these findings are helpful to supplement and expand the WPS theory in the continental lake basins in China,and provide theoretical guidance and technical support for oil and gas exploration in the Qaidam Basin.
基金supported by the National Science&Technology Specific Project,China(No.2016ZX05024-003-008).
文摘The Bozhong19-6(BZ19-6)condensate gas reservoirs,located in the southwestern Bozhong sub-basin,Bohai Bay Basin,China,were paleo-oil reservoirs in the geological past and have undergone at least three successive hydrocarbon charging events.The hydrocarbon migration and accumulation process of“early oil and late gas”has occurred in the current reservoirs.At the end of the sedimentation of the Guantao Formation(N_(1)g,∼12 Ma),the reservoirs began to fill with first stage low-moderate mature crude oil.At the late stage of the Lower Minghuazhen Formation(N_(1)ml)(∼6.7 Ma),the reservoirs were largely charged with second stage high mature crude oil.Since the deposition of the upper Minghuazhen Formation(N_(2)m^(u),∼5.1 Ma),the paleo-oil reservoirs were transformed into shallow Neogene reservoirs due to the reactivation of basement faults.From the late stage of the N_(2)m^(u)to the present day(∼2.8–0 Ma),the reservoirs were rapidly filled by natural gas within a short period.In addition,analysis of the formation of the reservoir bitumen and the conspicuous loss of the lower molecular weight n-alkanes in the crude oil reveal that the injection of a large amount of gas in the late stage caused gas flushing of the early charged oil.
文摘In northwestern Ordos Basin, the Triassic reservoir Chang 9 has favorable reservoir forming conditions, extensive reservoir development, and huge potential for oil exploration and exploitation. Studying the main controlling factors and accumulation model of Chang 9 reservoir in this area can provide a basis for the production targets, and assist in formulating reasonable development technology policy. In this paper, to explore and summarize the hydrocarbon accumulation model, the Chang 9 reservoir were analyzed from the aspects of oil source, fracture, oil migration, structure, lithology and reservoir physical properties for the main controlling factors in this area. Organic geochemical and geological comprehensive analysis that the oil-source of the Chang 9 reservoir in the northwest of Ordos Basin is derived from Chang 7 hydrocarbon source rocks. The fractures provide a sound channel for the "vertical multi-point filling" of the oil source from Chang 7 to Chang 9. The crude oil migrates vertically from Chang 7 to Chang 9, then expands horizontally to form a reservoir. Structures play an important role in controlling the distribution of reservoirs, the control by sand in small layer and physical property is also obvious. This paper creatively establishes the reservoir accumulation model of Chang 9 in northwest of Ordos Basin, which is characterized by Vertical multi-point filling, horizontal expansion becomes oil pool. It reveals the genetic mechanism of the development of Chang 9 multi-reservoir in the study area, which provides guidance for exploration and evaluation deployment.