Upper Ordovician-Lower Silurian Wufeng-Longmaxi Formation is the most developed strata of shale gas in southern China.Due to the complex sedimentary environment adjacent to the Kangdian Uplift,the favorable area for o...Upper Ordovician-Lower Silurian Wufeng-Longmaxi Formation is the most developed strata of shale gas in southern China.Due to the complex sedimentary environment adjacent to the Kangdian Uplift,the favorable area for organic-rich shale development is still undetermined.The authors,therefore,focus on the mechanism of accumulation of organic matter and the characterization of the sedimentary environment of the Wufeng-Longmaxi Shales to have a more complete understanding and new discovering of organic matter enrichment and favorable area in the marginal region around Sichuan Basin.Multiple methods were applied in this study,including thin section identification,scanning electron microscopy(SEM)observations and X-ray diffraction(XRD),and elemental analysis on outcrop samples.Five lithofacies have been defined according to the mineralogical and petrological analyses,including mudstone,bioclastic limestone,silty shale,dolomitic shale,and carbonaceous siliceous shale.The paleo-environments have been reconstructed and the organic enrichment mechanism has been identified as a reduced environment and high productivity.The Wufeng period is generally a suboxic environment and the early Longmaxi period is a reducing environment based on geochemical characterization.High dolomite content in the study area is accompanied by high TOC,which may potentially indicate the restricted anoxic environment formed by biological flourishing in shallower water.And for the area close to the Kangdian Uplift,the shale gas generation capability is comparatively favorable.The geochemical parameters implied that new favorable areas for shale gas exploration could be targeted,and more shale gas resources in the mountain-basin transitional zone might be identified in the future.展开更多
The Pearl River Mouth Basin(PRMB)is one of the most petroliferous basins on the northern margin of the South China Sea.Knowledge of the thermal history of the PRMB is significant for understanding its tectonic evoluti...The Pearl River Mouth Basin(PRMB)is one of the most petroliferous basins on the northern margin of the South China Sea.Knowledge of the thermal history of the PRMB is significant for understanding its tectonic evolution and for unraveling its poorly studied source-rock maturation history.Our investigations in this study are based on apatite fission-track(AFT)thermochronology analysis of 12 cutting samples from 4 boreholes.Both AFT ages and length data suggested that the PRMB has experienced quite complicated thermal evolution.Thermal history modeling results unraveled four successive events of heating separated by three stages of cooling since the early Middle Eocene.The cooling events occurred approximately in the Late Eocene,early Oligocene,and the Late Miocene,possibly attributed to the Zhuqiong II Event,Nanhai Event,and Dongsha Event,respectively.The erosion amount during the first cooling stage is roughly estimated to be about 455-712 m,with an erosion rate of 0.08-0.12 mm/a.The second erosion-driven cooling is stronger than the first one,with an erosion amount of about 747-814 m and an erosion rate between about 0.13-0.21 mm/a.The erosion amount calculated related to the third cooling event varies from 800 m to 3419 m,which is speculative due to the possible influence of the magmatic activity.展开更多
As a prerequisite and a guarantee for safe and efficient natural gas hydrates(NGHs)exploitation,it is imperative to effectively determine the mechanical properties of NGHs reservoirs and clarify the law of the change ...As a prerequisite and a guarantee for safe and efficient natural gas hydrates(NGHs)exploitation,it is imperative to effectively determine the mechanical properties of NGHs reservoirs and clarify the law of the change in the mechanical properties with the dissociation of NGHs during NGHs production tests by depressurization.Based on the development of Japan’s two offshore NGHs production tests in vertical wells,this study innovatively proposed a new subsea communication technology-accurate directional connection using a wet-mate connector.This helps to overcome the technical barrier to the communication between the upper and lower completion of offshore wells.Using this new communication technology,this study explored and designed a mechanical monitoring scheme for lower completion(sand screens).This scheme can be used to monitor the tensile stress and radial compressive stress of sand screens caused by NGHs reservoirs in real time,thus promoting the technical development for the rapid assessment and real-time feedback of the in-situ mechanical response of NGHs reservoirs during offshore NGHs production tests by depressurization.展开更多
The Ordos Basin is the largest continental multi-energy mineral basin in China,which is rich in coal,oil and gas,and uranium resources.The exploitation of mineral resources is closely related to reservoir water.The ch...The Ordos Basin is the largest continental multi-energy mineral basin in China,which is rich in coal,oil and gas,and uranium resources.The exploitation of mineral resources is closely related to reservoir water.The chemical properties of reservoir water are very important for reservoir evaluation and are significant indicators of the sealing of reservoir oil and gas resources.Therefore,the caprock of the Chang 6 reservoir in the Yanchang Formation was evaluated.The authors tested and analyzed the chemical characteristics of water samples selected from 30 wells in the Chang 6 reservoir of Ansai Oilfield in the Ordos Basin.The results show that the Chang 6 reservoir water in Ansai Oilfield is dominated by calcium-chloride water type with a sodium chloride coefficient of generally less than 0.5.The chloride magnesium coefficients are between 33.7 and 925.5,most of which are greater than 200.The desulfurization coefficients range from 0.21 to 13.4,with an average of 2.227.The carbonate balance coefficients are mainly concentrated below 0.01,with an average of 0.008.The calcium and magnesium coefficients are between 0.08 and 0.003,with an average of 0.01.Combined with the characteristics of the four-corner layout of the reservoir water,the above results show that the graphics are basically consistent.The study indicates that the Chang 6 reservoir in Ansai Oilfield in the Ordos Basin is a favorable block for oil and gas storage with good sealing properties,great preservation conditions of oil and gas,and high pore connectivity.展开更多
The shale gas resources in China have great potential and the geological resources of shale gas is over 100×10^(12)m^(3),which includes about 20×10^(12)m^(3) of recoverable resources.Organic-rich shales can ...The shale gas resources in China have great potential and the geological resources of shale gas is over 100×10^(12)m^(3),which includes about 20×10^(12)m^(3) of recoverable resources.Organic-rich shales can be divided into three types according to their sedimentary environments,namely marine,marine-continental transitional,and continental shales,which are distributed in 13 stratigraphic systems from the Mesoproterozoic to the Cenozoic.The Sichuan Basin and its surrounding areas have the highest geological resources of shale gas,and the commercial development of shale gas has been achieved in the Upper Ordovician Wufeng Formation-Lower Silurian Longmaxi Formation in these areas,with a shale gas production of up to 20×10^(9)m^(3) in 2020.China has seen rapid shale gas exploration and development over the last five years,successively achieving breakthroughs and important findings in many areas and strata.The details are as follows.(1)Large-scale development of middle-shallow shale gas(burial depth:less than 3500 m)has been realized,with the productivity having rapidly increased;(2)breakthroughs have been constantly made in the development of deep shale gas(burial depth:3500-4500 m),and the ultradeep shale gas(burial depth:greater than 4500 m)is under testing;(3)breakthroughs have been made in the development of normal-pressure shale gas,and the assessment of the shale gas in complex tectonic areas is being accelerated;(4)shale gas has been frequently discovered in new areas and new strata,exhibiting a great prospect.Based on the exploration and development practice,three aspects of consensus have been gradually reached on the research progress in the geological theories of shale gas achieved in China.(1)in terms of deep-water fine-grained sediments,organic-rich shales are the base for the formation of shale gas;(2)in terms of high-quality reservoirs,the development of micro-nano organic matter-hosted pores serves as the core of shale gas accumulation;(3)in terms of preservation conditions,weak structural transformation,a moderate degree of thermal evolution,and a high pressure coefficient are the key to shale gas enrichment.As a type of important low-carbon fossil energy,shale gas will play an increasingly important role in achieving the strategic goals of peak carbon dioxide emissions and carbon neutrality.Based on the in-depth study of shale gas geological conditions and current exploration progress,three important directions for shale gas exploration in China in the next five years are put forward.展开更多
Increasing interests in hydrocarbon resources at depths have drawn greater attentions to the deeply-buried carbonate reservoirs in the Tarim Basin in China.In this study,the cyclic dolomite rocks of Upper Cambrian Low...Increasing interests in hydrocarbon resources at depths have drawn greater attentions to the deeply-buried carbonate reservoirs in the Tarim Basin in China.In this study,the cyclic dolomite rocks of Upper Cambrian Lower Qiulitag Group from four outcrop sections in northwestern Tarim Basin were selected to investigate and evaluate the petrophysical properties in relation to depositional facies and cyclicity.The Lower Qiulitag Group includes ten lithofacies,which were deposited in intermediate to shallow subtidal,restricted shallow subtidal,intertidal,and supratidal environments on a carbonate ramp system.These lithofacies are vertically stacked into repeated shallowing-upward,meter-scale cycles which are further grouped into six third-order depositional sequences(Sq1 to Sq6).There are variable types of pore spaces in the Lower Qiulitag Group dolomite rocks,including interparticle,intraparticle,and fenestral pores of primary origin,inter crystal,and vuggy pores of late diagenetic modification.The porosity in the dolomites is generally facies-selective as that the microbially-originated thrombolites and stromatolites generally yield a relatively high porosity.In contrast,the high-energy ooidal grainstones generally have very low porosity.In this case,the microbialite-based peritidal cycles and peritidal cycle-dominated highstand(or regressive)successions have relatively high volumes of pore spaces,although highly fluctuating(or vertical inhomogeneous).Accordingly,the grainstone-based subtidal cycles and subtidal cycle-dominated transgressive successions generally yield extremely low porosity.This scenario indicates that porosity development and preservation in the thick dolomite successions are primarily controlled by depositional facies which were influenced by sea-level fluctuations of different orders and later diagenetic overprinting.展开更多
In this paper,substantial domestic and foreign research results of microscopic shale reservoir space were systemically reviewed,the research history consisting of simple observation and qualitative classification,quan...In this paper,substantial domestic and foreign research results of microscopic shale reservoir space were systemically reviewed,the research history consisting of simple observation and qualitative classification,quantitative research,the combination of qualitative and quantitative research successively as well as the characteristics of each research stage were summarized.In addition,the current problems existing in the characterization methods of shale reservoir space were also analyzed.Furthermore,based on massive actual detection of typical core samples obtained from more than 50 global shale gas wells and relevant practical experience,a comprehensive characterization method of combining qualitative with the semiquantitative characterization was put forward.In detail,the indicators of the qualitative characterization include pore combination type and organic-matter microscopic morphology type,while the core elements of the semi-quantitative characterization include the percentage of the organic-matter area and the plane porosity of the pores of different types.Based on the reference of the naming and classification of rocks,the three-end-member diagram method was used to characterize microscopic shale reservoir space.This is achieved by plotting the three end-member diagram of 3 kinds of first-order critical reservoir spaces,i.e.,organic-matter pores,matrix pores,and micro-fractures,in order to intuitively present the features of the microscopic pore combination.Meanwhile,statistic histograms of organic-matter microscopic morphology type and the plane porosity of different types of pores were adopted to characterize the development degree of second-order pores quantitatively.By this comprehensive characterization method,the importance of both pore combination and the microscopic morphology of organic matter were emphasized,revealing the control of organic-matter microscopic morphology over the organic-matter pores.What is more,high-resolution FE-SEM was adopted to obtain semi-quantitative statistics results.In this way,the features of pore development and pore combination were quantified,not only reflecting the types and storage capacity of the microscopic shale reservoir space,but also presenting the hydrocarbongenerating potential of organic matter in shale.Therefore,the results of this research are capable of providing in-depth microscopic information for the assessment and exploration and development of shale gas resources.展开更多
The Lower Cretaceous Yingcheng Formation in the southern Songliao Basin is the typical tight oil sandstone in China.In order to better predict the petrophysical properties of the tight sandstone reservoirs in the Lowe...The Lower Cretaceous Yingcheng Formation in the southern Songliao Basin is the typical tight oil sandstone in China.In order to better predict the petrophysical properties of the tight sandstone reservoirs in the Lower Cretaceous Yingcheng Formation,Songliao Basin,Northeast China,the diagenesis and porosity evolution was investigated using a suite of petrographic and geochemical techniques including thin section analysis,scanning electron microscopy,mercury intrusion and fluid inclusion analysis,on a set of selected tight sandstone samples.Combined with the histories of burial evolution,organic matter thermal evolution and hydrocarbon charge,the matching relationship between reservoir porosity evolution and hydrocarbon accumulation history is analyzed.The result showed that the tight sandstone reservoirs characterized of being controlled by deposition,predominated by compaction,improved by dissolution and enhanced by cementation.The hydrocarbon accumulation period was investigated using a suite of hydrocarbon generation and expulsion history,microfluorescence determination and temperature measurement technology.According to the homogenization temperature of the inclusions and the history of burial evolution,Yingcheng Formation has mainly two phases hydrocarbon accumulation.The first phase of oil and gas is charged before the reservoir is tightened,the oil and gas generated by Shahezi source rocks enter the sand body of Yingcheng Formation,influenced by the carrying capability of sand conducting layer,oil and gas is mainly conducted by the better properties and higher connectivity sand body and enriched in the east,which belongs to the type of densification after hydrocarbon accumulation.The second phase of oil and gas charge after densification,which belongs to the type of densification before the hydrocarbon accumulation.展开更多
基金jointly funded by the National Key Laboratory of Oil and Gas Reservoir Geology and Exploitation(PLC20210104)China Geological Survey(DD20221661)China National Science and Technology Major Project“Test and Application of Shale Gas Exploration and Evaluation Technology(2016ZX05034004)”。
文摘Upper Ordovician-Lower Silurian Wufeng-Longmaxi Formation is the most developed strata of shale gas in southern China.Due to the complex sedimentary environment adjacent to the Kangdian Uplift,the favorable area for organic-rich shale development is still undetermined.The authors,therefore,focus on the mechanism of accumulation of organic matter and the characterization of the sedimentary environment of the Wufeng-Longmaxi Shales to have a more complete understanding and new discovering of organic matter enrichment and favorable area in the marginal region around Sichuan Basin.Multiple methods were applied in this study,including thin section identification,scanning electron microscopy(SEM)observations and X-ray diffraction(XRD),and elemental analysis on outcrop samples.Five lithofacies have been defined according to the mineralogical and petrological analyses,including mudstone,bioclastic limestone,silty shale,dolomitic shale,and carbonaceous siliceous shale.The paleo-environments have been reconstructed and the organic enrichment mechanism has been identified as a reduced environment and high productivity.The Wufeng period is generally a suboxic environment and the early Longmaxi period is a reducing environment based on geochemical characterization.High dolomite content in the study area is accompanied by high TOC,which may potentially indicate the restricted anoxic environment formed by biological flourishing in shallower water.And for the area close to the Kangdian Uplift,the shale gas generation capability is comparatively favorable.The geochemical parameters implied that new favorable areas for shale gas exploration could be targeted,and more shale gas resources in the mountain-basin transitional zone might be identified in the future.
基金This study is financially supported by the National Natural Science Foundation of China(42072181).
文摘The Pearl River Mouth Basin(PRMB)is one of the most petroliferous basins on the northern margin of the South China Sea.Knowledge of the thermal history of the PRMB is significant for understanding its tectonic evolution and for unraveling its poorly studied source-rock maturation history.Our investigations in this study are based on apatite fission-track(AFT)thermochronology analysis of 12 cutting samples from 4 boreholes.Both AFT ages and length data suggested that the PRMB has experienced quite complicated thermal evolution.Thermal history modeling results unraveled four successive events of heating separated by three stages of cooling since the early Middle Eocene.The cooling events occurred approximately in the Late Eocene,early Oligocene,and the Late Miocene,possibly attributed to the Zhuqiong II Event,Nanhai Event,and Dongsha Event,respectively.The erosion amount during the first cooling stage is roughly estimated to be about 455-712 m,with an erosion rate of 0.08-0.12 mm/a.The second erosion-driven cooling is stronger than the first one,with an erosion amount of about 747-814 m and an erosion rate between about 0.13-0.21 mm/a.The erosion amount calculated related to the third cooling event varies from 800 m to 3419 m,which is speculative due to the possible influence of the magmatic activity.
基金supported jointly by the major projects of Basic and Applied Basic Research in Guangdong Province“Key Basic Theory Research for Natural Gas Hydrate Trial Production in Shenhu Pilot Test Area”(2020B0301030003)the project from Southern Marine Science&Engineering Guangdong Laboratory in Guangzhou City“Research on New Closed Circulation Drilling Technology without Riser”(GML2019ZD0501).
文摘As a prerequisite and a guarantee for safe and efficient natural gas hydrates(NGHs)exploitation,it is imperative to effectively determine the mechanical properties of NGHs reservoirs and clarify the law of the change in the mechanical properties with the dissociation of NGHs during NGHs production tests by depressurization.Based on the development of Japan’s two offshore NGHs production tests in vertical wells,this study innovatively proposed a new subsea communication technology-accurate directional connection using a wet-mate connector.This helps to overcome the technical barrier to the communication between the upper and lower completion of offshore wells.Using this new communication technology,this study explored and designed a mechanical monitoring scheme for lower completion(sand screens).This scheme can be used to monitor the tensile stress and radial compressive stress of sand screens caused by NGHs reservoirs in real time,thus promoting the technical development for the rapid assessment and real-time feedback of the in-situ mechanical response of NGHs reservoirs during offshore NGHs production tests by depressurization.
基金supported by the Jiangsu Natural Science Foundation project(SBK2021045820)the Chongqing Natural Science Foundation general Project(cstc2021jcyj-msxmX0624)+1 种基金the Graduate Innovation Program of China University of Mining and Technology(2022WLKXJ002)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(KYCX22_2600).
文摘The Ordos Basin is the largest continental multi-energy mineral basin in China,which is rich in coal,oil and gas,and uranium resources.The exploitation of mineral resources is closely related to reservoir water.The chemical properties of reservoir water are very important for reservoir evaluation and are significant indicators of the sealing of reservoir oil and gas resources.Therefore,the caprock of the Chang 6 reservoir in the Yanchang Formation was evaluated.The authors tested and analyzed the chemical characteristics of water samples selected from 30 wells in the Chang 6 reservoir of Ansai Oilfield in the Ordos Basin.The results show that the Chang 6 reservoir water in Ansai Oilfield is dominated by calcium-chloride water type with a sodium chloride coefficient of generally less than 0.5.The chloride magnesium coefficients are between 33.7 and 925.5,most of which are greater than 200.The desulfurization coefficients range from 0.21 to 13.4,with an average of 2.227.The carbonate balance coefficients are mainly concentrated below 0.01,with an average of 0.008.The calcium and magnesium coefficients are between 0.08 and 0.003,with an average of 0.01.Combined with the characteristics of the four-corner layout of the reservoir water,the above results show that the graphics are basically consistent.The study indicates that the Chang 6 reservoir in Ansai Oilfield in the Ordos Basin is a favorable block for oil and gas storage with good sealing properties,great preservation conditions of oil and gas,and high pore connectivity.
基金supported by a project of shale gas in Southern China(DD20190561)initiated by the China Geological Surveythe project for High-level Innovative Talents in Science and Technology,Ministry of Natural Resources(12110600000018003918)。
文摘The shale gas resources in China have great potential and the geological resources of shale gas is over 100×10^(12)m^(3),which includes about 20×10^(12)m^(3) of recoverable resources.Organic-rich shales can be divided into three types according to their sedimentary environments,namely marine,marine-continental transitional,and continental shales,which are distributed in 13 stratigraphic systems from the Mesoproterozoic to the Cenozoic.The Sichuan Basin and its surrounding areas have the highest geological resources of shale gas,and the commercial development of shale gas has been achieved in the Upper Ordovician Wufeng Formation-Lower Silurian Longmaxi Formation in these areas,with a shale gas production of up to 20×10^(9)m^(3) in 2020.China has seen rapid shale gas exploration and development over the last five years,successively achieving breakthroughs and important findings in many areas and strata.The details are as follows.(1)Large-scale development of middle-shallow shale gas(burial depth:less than 3500 m)has been realized,with the productivity having rapidly increased;(2)breakthroughs have been constantly made in the development of deep shale gas(burial depth:3500-4500 m),and the ultradeep shale gas(burial depth:greater than 4500 m)is under testing;(3)breakthroughs have been made in the development of normal-pressure shale gas,and the assessment of the shale gas in complex tectonic areas is being accelerated;(4)shale gas has been frequently discovered in new areas and new strata,exhibiting a great prospect.Based on the exploration and development practice,three aspects of consensus have been gradually reached on the research progress in the geological theories of shale gas achieved in China.(1)in terms of deep-water fine-grained sediments,organic-rich shales are the base for the formation of shale gas;(2)in terms of high-quality reservoirs,the development of micro-nano organic matter-hosted pores serves as the core of shale gas accumulation;(3)in terms of preservation conditions,weak structural transformation,a moderate degree of thermal evolution,and a high pressure coefficient are the key to shale gas enrichment.As a type of important low-carbon fossil energy,shale gas will play an increasingly important role in achieving the strategic goals of peak carbon dioxide emissions and carbon neutrality.Based on the in-depth study of shale gas geological conditions and current exploration progress,three important directions for shale gas exploration in China in the next five years are put forward.
基金funded by geological survey projects of China Geological Survey(DD20190405,DD20190406)National Science and Technology Special Project of China(2011ZX0500803)National Basic Research Project(2012CB214802).
文摘Increasing interests in hydrocarbon resources at depths have drawn greater attentions to the deeply-buried carbonate reservoirs in the Tarim Basin in China.In this study,the cyclic dolomite rocks of Upper Cambrian Lower Qiulitag Group from four outcrop sections in northwestern Tarim Basin were selected to investigate and evaluate the petrophysical properties in relation to depositional facies and cyclicity.The Lower Qiulitag Group includes ten lithofacies,which were deposited in intermediate to shallow subtidal,restricted shallow subtidal,intertidal,and supratidal environments on a carbonate ramp system.These lithofacies are vertically stacked into repeated shallowing-upward,meter-scale cycles which are further grouped into six third-order depositional sequences(Sq1 to Sq6).There are variable types of pore spaces in the Lower Qiulitag Group dolomite rocks,including interparticle,intraparticle,and fenestral pores of primary origin,inter crystal,and vuggy pores of late diagenetic modification.The porosity in the dolomites is generally facies-selective as that the microbially-originated thrombolites and stromatolites generally yield a relatively high porosity.In contrast,the high-energy ooidal grainstones generally have very low porosity.In this case,the microbialite-based peritidal cycles and peritidal cycle-dominated highstand(or regressive)successions have relatively high volumes of pore spaces,although highly fluctuating(or vertical inhomogeneous).Accordingly,the grainstone-based subtidal cycles and subtidal cycle-dominated transgressive successions generally yield extremely low porosity.This scenario indicates that porosity development and preservation in the thick dolomite successions are primarily controlled by depositional facies which were influenced by sea-level fluctuations of different orders and later diagenetic overprinting.
基金This study was supported by the National Scientific and Technological Major Special Project titled“Research on Evaluation Method and Exploration Technology on Shale Gas Resources”(2016ZX05034)“Shale Gas Basic Geological Survey Project in South China”(121201229000160021)initiated by CGSinter-governmental cooperation project titled“China-USA Cooperation Research Project of Carboniferous-Permian Shale Reservoir Evaluation Technology”(2017YFE0106300).
文摘In this paper,substantial domestic and foreign research results of microscopic shale reservoir space were systemically reviewed,the research history consisting of simple observation and qualitative classification,quantitative research,the combination of qualitative and quantitative research successively as well as the characteristics of each research stage were summarized.In addition,the current problems existing in the characterization methods of shale reservoir space were also analyzed.Furthermore,based on massive actual detection of typical core samples obtained from more than 50 global shale gas wells and relevant practical experience,a comprehensive characterization method of combining qualitative with the semiquantitative characterization was put forward.In detail,the indicators of the qualitative characterization include pore combination type and organic-matter microscopic morphology type,while the core elements of the semi-quantitative characterization include the percentage of the organic-matter area and the plane porosity of the pores of different types.Based on the reference of the naming and classification of rocks,the three-end-member diagram method was used to characterize microscopic shale reservoir space.This is achieved by plotting the three end-member diagram of 3 kinds of first-order critical reservoir spaces,i.e.,organic-matter pores,matrix pores,and micro-fractures,in order to intuitively present the features of the microscopic pore combination.Meanwhile,statistic histograms of organic-matter microscopic morphology type and the plane porosity of different types of pores were adopted to characterize the development degree of second-order pores quantitatively.By this comprehensive characterization method,the importance of both pore combination and the microscopic morphology of organic matter were emphasized,revealing the control of organic-matter microscopic morphology over the organic-matter pores.What is more,high-resolution FE-SEM was adopted to obtain semi-quantitative statistics results.In this way,the features of pore development and pore combination were quantified,not only reflecting the types and storage capacity of the microscopic shale reservoir space,but also presenting the hydrocarbongenerating potential of organic matter in shale.Therefore,the results of this research are capable of providing in-depth microscopic information for the assessment and exploration and development of shale gas resources.
基金The authors acknowledge sponsorship from China Petroleum Science and Technology Innovation Fund(2017d-5007-0101)China Geological Survey project(DD20191007)Key Special Project for Introduced Talents Team of Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou)(GML2019ZD0207).
文摘The Lower Cretaceous Yingcheng Formation in the southern Songliao Basin is the typical tight oil sandstone in China.In order to better predict the petrophysical properties of the tight sandstone reservoirs in the Lower Cretaceous Yingcheng Formation,Songliao Basin,Northeast China,the diagenesis and porosity evolution was investigated using a suite of petrographic and geochemical techniques including thin section analysis,scanning electron microscopy,mercury intrusion and fluid inclusion analysis,on a set of selected tight sandstone samples.Combined with the histories of burial evolution,organic matter thermal evolution and hydrocarbon charge,the matching relationship between reservoir porosity evolution and hydrocarbon accumulation history is analyzed.The result showed that the tight sandstone reservoirs characterized of being controlled by deposition,predominated by compaction,improved by dissolution and enhanced by cementation.The hydrocarbon accumulation period was investigated using a suite of hydrocarbon generation and expulsion history,microfluorescence determination and temperature measurement technology.According to the homogenization temperature of the inclusions and the history of burial evolution,Yingcheng Formation has mainly two phases hydrocarbon accumulation.The first phase of oil and gas is charged before the reservoir is tightened,the oil and gas generated by Shahezi source rocks enter the sand body of Yingcheng Formation,influenced by the carrying capability of sand conducting layer,oil and gas is mainly conducted by the better properties and higher connectivity sand body and enriched in the east,which belongs to the type of densification after hydrocarbon accumulation.The second phase of oil and gas charge after densification,which belongs to the type of densification before the hydrocarbon accumulation.
