Based on 2D and 3D seismic data and well logging data,this paper studies the distribution of well-seismic stratigraphic filling and shoal controlled reservoirs of Upper Cambrian Xixiangchi Formation in the south slope...Based on 2D and 3D seismic data and well logging data,this paper studies the distribution of well-seismic stratigraphic filling and shoal controlled reservoirs of Upper Cambrian Xixiangchi Formation in the south slope of Leshan-Longnüsi paleouplift in the Sichuan Basin,to reveal the genetic relationship between stratigraphic filling,paleogeomorphology and large-scale grain shoal.(1)The Xixiangchi Formation in the study area is overlapped and filled gradually to the Leshan-Longnüsi paleouplift,but gets thin sharply due to truncation only near the denudation pinch-out line of the paleouplift.Two overlap slope break belts and one erosion slope break belt are identified,and the Xixiangchi Formation is divided into 4 members from bottom to top.(2)The filling pattern of the overlapping at the base and erosion at the top indicates that the thickness of Xixiangchi Formation can reflect the pre-depositional paleogeomorphology,and reveals that the studied area has a monoclinal geomorphic feature of plunging to southeast and being controlled by multistage slope break belts.(3)The large-scale grain shoals and shoal controlled reservoirs are developed longitudinally in the third and fourth members of the Xixiangchi Formation,and laterally in the vicinity of the multistage overlap slope break belts.(4)Overlap slope break belts are closely related to northwest trending reverse faults.The western margin of the South China Plate converging with the Qiangtang-Himalaya massif in the middle-late Cambrian resulted in the rapid uplift of the northwestern margin of the Yangtze Plate and expanding toward southeast,leaving gradually plunging multistage slope breaks and large-scale northeast grain shoal reservoir belts.Considering oil and gas test results,it is predicted that the favorable exploration zone of the grain shoal controlled reservoirs covers an area of 3340 km^(2).展开更多
In the Sichuan Basin,the Middle Permian marine carbonate rocks are important natural gas pay zones with immense exploration potential,but the facies belts and distribution situations of layered dolomite reservoirs are...In the Sichuan Basin,the Middle Permian marine carbonate rocks are important natural gas pay zones with immense exploration potential,but the facies belts and distribution situations of layered dolomite reservoirs are not clear,which hinders the progress in natural gas exploration.In view of the sedimentary background of the Sichuan Basin,field outcrop section,drilling data and seismic data were comprehensively analyzed with the favorable reservoir intervals in the framework of sequence stratigraphy as the key research units.Research results about its lithofacies paleogeography were obtained as follows.First,a gentle slope SW high and NE low was presented during the sedimentation of the Qixia Fm in the Middle Permian.In the Maokou Fm of the Middle Permian,however,a series of the N-W trending intra-platform rifts were developed in this setting,and eventually a paleogeographic pattern of NE-dipping alternative uplift and depression was evolved.Second,in the Qixia Fm,the transgressive tract was in an open platform environment and the highstand system tract evolved into a rimmed platform.And the platform margin beach in the area of Jiange-Ya'an is the favorable reservoir facies belt.And third,in the Maokou Fm,the transgressive tract was in the carbonate shelf environment and the highstand system tract evolved into a rimmed platform.And the platform margin reef flat in the area of Jiange-Ya'an and the syneclise margin beach in the area of YantingeGuang'an are favorable reservoir facies belts.It is concluded that the two grain beach facies belts in the areas of Jiange-Ya'an and YantingeGuang'an were the favorable zones for the large-scale development of Middle Permian layered dolomite reservoirs and they are the main target of subsequent natural gas exploration.展开更多
Based on the research progress of the geological theory of coal-formed gas,the contributions of coal-formed gas to the natural gas reserves and production in China and to the development of natural gas in major gas-pr...Based on the research progress of the geological theory of coal-formed gas,the contributions of coal-formed gas to the natural gas reserves and production in China and to the development of natural gas in major gas-producing basins are analyzed,and the key favorable exploration zones for coal-formed gas in China are comprehensively evaluated.The following results are obtained.First,coal measures are good gas source rocks,and hydrocarbon generation from coal measure was dominated by gas,followed by oil.Second,a natural gas genetic identification index system based on stable isotopes,light hydrocarbon components,and biomarkers is established.Third,the quantitative and semi-quantitative factors controlling the formation of large gas fields,represented by the indicator of gas generation intensity greater than 20×10^(8) m^(3)/km^(2),are identified to guide the discovery of large gas fields in China.Fourth,coal-formed gas is the major contributor to the current natural gas reserves and production of China,both accounting for over 55%.The high proportion of coal-formed gas has enabled the Tarim,Sichuan and Ordos basins to be the major gas production areas in China.Fifth,coal rock gas is an important field for future exploration of coal-formed gas,and key zones include the Carboniferous Benxi Formation(Fm.)in the Wushenqi-Mizhi area of the Ordos Basin,the Permian Longtan Fm.in central-southern Sichuan Basin,the Jurassic Xishanyao Fm.in the southern margin and Luliang uplift of the Junggar Basin.Sixth,tight gas is the main area for increasing reserves and production,and the favorable exploration zones include the Carboniferous-Permian in southern Ordos Basin and the Bohai Bay Basin,and the Triassic Xujiahe Fm.in the transition zone between central and western Sichuan Basin.Seventh,the Jurassic in the southern margin of the Junggar Basin is a key favorable exploration zone for subsequent investigation of conventional coal-formed gas.These insights have valuable theoretical and practical significance for further developing and improving the theory of coal-formed gas,and guiding the exploration of coal-formed gas fields in China.展开更多
Progress of natural gas exploration has recently been made in the Upper Paleozoic marine-facies reservoirs in the NW Sichuan Basin.It has been proved that the Middle Permian Qixia Fm pore-type dolomite reservoirs may ...Progress of natural gas exploration has recently been made in the Upper Paleozoic marine-facies reservoirs in the NW Sichuan Basin.It has been proved that the Middle Permian Qixia Fm pore-type dolomite reservoirs may be distributed continuously in a large area,besides,for thefirst time favorable gas-bearing Devonian dolomite reservoirs in great thickness were discovered in the downhole there.Recent research achievements indicate that:(1)The Lower Cambrian quality source rocks in huge thickness were found in the study sedimentary area with advantageous hydrocarbon source conditions.(2)Influenced by the Caledonian movement,the whole NW Sichuan Basin was lifted up to form a massive box-like NS-trending plunging uplift low steep in the west but high sluggish in the east,laying a robust foundation for the inheritance of Devonian,Carboniferous,and Permian platform margin reef large-scale sedimentation and dolomitization.(3)In the Upper Paleozoic strata,there were multiple planes of unconformity and multi-stage supergene karst occurred,improving the preservation and seeping capacity of reservoirs.(4)Tectonic deformations resulted from the nappe structure in the Longmenshan Mountain provided good hydrocarbon source fractures and sealing conditions for oil and gas reservoirs,which is conductive to the formation of a giant gas pool.It is concluded that the back-thrust anticline belt east to Hidden fault I in this study area has favorable conditions for large-scale structuralestratigraphic and structur-alelithologic combination traps.As suggested in this study,relatively strong dolomitization was found in the Qixia Fm in the Shejianhe RivereZhongba higher palaeogeomorphic deposit area,so the most favorable exploration target of the Qixia Fm will be around the central axis of Caledonian paleo-uplift to the east ridgeline,and the most favorable prospect of the Upper Palaeozoic will be the central axis to the west of Hidden fault I where three gas bearing reservoirs will be possibly explored at the same time.展开更多
Based on comprehensive analysis of cores,thin sections,logging and seismic data,the sequence stratigraphy and sedimentary evolution of the third and fourth members of Sinian Dengying Formation(Deng 3 and Deng 4 member...Based on comprehensive analysis of cores,thin sections,logging and seismic data,the sequence stratigraphy and sedimentary evolution of the third and fourth members of Sinian Dengying Formation(Deng 3 and Deng 4 members for short)in the Gaomo area of Sichuan Basin were investigated,and the favorable zones for reservoir development in the Deng 3 Member and Deng 4 Member were predicted.(1)Two Type I and one Type II sequence boundaries are identified in the Deng 3 and Deng 4 members.Based on the identified sequence boundaries,the Deng 3 and Deng 4 members can be divided into two third order sequences SQ3 and SQ4,which are well-developed,isochronal and traceable in this area;the SQ3 thins from west to the east,and the SQ4 thins from northwest to southeast.(2)The sedimentary environment from the depositional period of SQ3 to SQ4 has experienced the evolution from mixed platform to rimmed platform,and the platform rimmed system on the west side is characterized by the development of platform margin microbial mound and grain shoal assemblages.The intraplatform area is a restricted platform facies composed of a variety of dolomites,and there are local micro-geomorphic highlands of different scales and scattered intraplatform mounds and shoals.(3)The Deng 4 Member reservoirs,with obvious facies-controlled characteristic,are mainly distributed in the upper part of high-frequency upward shallow cycle and the high-stand systems tract of the third-order sequence vertically,and are more developed in the platform margin belt than in the intraplatform belt,and more developed in the Gaoshiti platform margin belt than in the west Suining platform margin belt on the plane.(4)Three types of favorable reservoir zones of Deng 4 Member have been finely delineated with 3D seismic data;among them,the mound and shoal facies zones developed in the ancient highlands of the intraplatform are the first choice for the next exploration and development of the Deng 4 Member.展开更多
基金Supported by the Cooperation Project of China National Natural Science Foundation and Petro China(U23B20154)Science and Technology Cooperation Project of Petro China and Southwest Petroleum University(2020CX010000)。
文摘Based on 2D and 3D seismic data and well logging data,this paper studies the distribution of well-seismic stratigraphic filling and shoal controlled reservoirs of Upper Cambrian Xixiangchi Formation in the south slope of Leshan-Longnüsi paleouplift in the Sichuan Basin,to reveal the genetic relationship between stratigraphic filling,paleogeomorphology and large-scale grain shoal.(1)The Xixiangchi Formation in the study area is overlapped and filled gradually to the Leshan-Longnüsi paleouplift,but gets thin sharply due to truncation only near the denudation pinch-out line of the paleouplift.Two overlap slope break belts and one erosion slope break belt are identified,and the Xixiangchi Formation is divided into 4 members from bottom to top.(2)The filling pattern of the overlapping at the base and erosion at the top indicates that the thickness of Xixiangchi Formation can reflect the pre-depositional paleogeomorphology,and reveals that the studied area has a monoclinal geomorphic feature of plunging to southeast and being controlled by multistage slope break belts.(3)The large-scale grain shoals and shoal controlled reservoirs are developed longitudinally in the third and fourth members of the Xixiangchi Formation,and laterally in the vicinity of the multistage overlap slope break belts.(4)Overlap slope break belts are closely related to northwest trending reverse faults.The western margin of the South China Plate converging with the Qiangtang-Himalaya massif in the middle-late Cambrian resulted in the rapid uplift of the northwestern margin of the Yangtze Plate and expanding toward southeast,leaving gradually plunging multistage slope breaks and large-scale northeast grain shoal reservoir belts.Considering oil and gas test results,it is predicted that the favorable exploration zone of the grain shoal controlled reservoirs covers an area of 3340 km^(2).
基金Project supported by the National Major S&T Project(No.2011ZX05004-002)the CNPC Major S&T Project(No.2014E-32).
文摘In the Sichuan Basin,the Middle Permian marine carbonate rocks are important natural gas pay zones with immense exploration potential,but the facies belts and distribution situations of layered dolomite reservoirs are not clear,which hinders the progress in natural gas exploration.In view of the sedimentary background of the Sichuan Basin,field outcrop section,drilling data and seismic data were comprehensively analyzed with the favorable reservoir intervals in the framework of sequence stratigraphy as the key research units.Research results about its lithofacies paleogeography were obtained as follows.First,a gentle slope SW high and NE low was presented during the sedimentation of the Qixia Fm in the Middle Permian.In the Maokou Fm of the Middle Permian,however,a series of the N-W trending intra-platform rifts were developed in this setting,and eventually a paleogeographic pattern of NE-dipping alternative uplift and depression was evolved.Second,in the Qixia Fm,the transgressive tract was in an open platform environment and the highstand system tract evolved into a rimmed platform.And the platform margin beach in the area of Jiange-Ya'an is the favorable reservoir facies belt.And third,in the Maokou Fm,the transgressive tract was in the carbonate shelf environment and the highstand system tract evolved into a rimmed platform.And the platform margin reef flat in the area of Jiange-Ya'an and the syneclise margin beach in the area of YantingeGuang'an are favorable reservoir facies belts.It is concluded that the two grain beach facies belts in the areas of Jiange-Ya'an and YantingeGuang'an were the favorable zones for the large-scale development of Middle Permian layered dolomite reservoirs and they are the main target of subsequent natural gas exploration.
基金Supported by the Petro China Science and Technology Project(2023YQX10101)National Natural Science Foundation of China(42372165)。
文摘Based on the research progress of the geological theory of coal-formed gas,the contributions of coal-formed gas to the natural gas reserves and production in China and to the development of natural gas in major gas-producing basins are analyzed,and the key favorable exploration zones for coal-formed gas in China are comprehensively evaluated.The following results are obtained.First,coal measures are good gas source rocks,and hydrocarbon generation from coal measure was dominated by gas,followed by oil.Second,a natural gas genetic identification index system based on stable isotopes,light hydrocarbon components,and biomarkers is established.Third,the quantitative and semi-quantitative factors controlling the formation of large gas fields,represented by the indicator of gas generation intensity greater than 20×10^(8) m^(3)/km^(2),are identified to guide the discovery of large gas fields in China.Fourth,coal-formed gas is the major contributor to the current natural gas reserves and production of China,both accounting for over 55%.The high proportion of coal-formed gas has enabled the Tarim,Sichuan and Ordos basins to be the major gas production areas in China.Fifth,coal rock gas is an important field for future exploration of coal-formed gas,and key zones include the Carboniferous Benxi Formation(Fm.)in the Wushenqi-Mizhi area of the Ordos Basin,the Permian Longtan Fm.in central-southern Sichuan Basin,the Jurassic Xishanyao Fm.in the southern margin and Luliang uplift of the Junggar Basin.Sixth,tight gas is the main area for increasing reserves and production,and the favorable exploration zones include the Carboniferous-Permian in southern Ordos Basin and the Bohai Bay Basin,and the Triassic Xujiahe Fm.in the transition zone between central and western Sichuan Basin.Seventh,the Jurassic in the southern margin of the Junggar Basin is a key favorable exploration zone for subsequent investigation of conventional coal-formed gas.These insights have valuable theoretical and practical significance for further developing and improving the theory of coal-formed gas,and guiding the exploration of coal-formed gas fields in China.
基金Supported by the National Science and TechnologyMajor Project"Permian-Middle Triassic natural gas accumulations and evaluation in the Sichuan Basin"(No.:2016ZX05007-004)PetroChina Science and Tech-nology Major Project"Deep marine carbonate exploration&development field experiments in the Sichuan Basin"(No.:2014E-3208(GF)).
文摘Progress of natural gas exploration has recently been made in the Upper Paleozoic marine-facies reservoirs in the NW Sichuan Basin.It has been proved that the Middle Permian Qixia Fm pore-type dolomite reservoirs may be distributed continuously in a large area,besides,for thefirst time favorable gas-bearing Devonian dolomite reservoirs in great thickness were discovered in the downhole there.Recent research achievements indicate that:(1)The Lower Cambrian quality source rocks in huge thickness were found in the study sedimentary area with advantageous hydrocarbon source conditions.(2)Influenced by the Caledonian movement,the whole NW Sichuan Basin was lifted up to form a massive box-like NS-trending plunging uplift low steep in the west but high sluggish in the east,laying a robust foundation for the inheritance of Devonian,Carboniferous,and Permian platform margin reef large-scale sedimentation and dolomitization.(3)In the Upper Paleozoic strata,there were multiple planes of unconformity and multi-stage supergene karst occurred,improving the preservation and seeping capacity of reservoirs.(4)Tectonic deformations resulted from the nappe structure in the Longmenshan Mountain provided good hydrocarbon source fractures and sealing conditions for oil and gas reservoirs,which is conductive to the formation of a giant gas pool.It is concluded that the back-thrust anticline belt east to Hidden fault I in this study area has favorable conditions for large-scale structuralestratigraphic and structur-alelithologic combination traps.As suggested in this study,relatively strong dolomitization was found in the Qixia Fm in the Shejianhe RivereZhongba higher palaeogeomorphic deposit area,so the most favorable exploration target of the Qixia Fm will be around the central axis of Caledonian paleo-uplift to the east ridgeline,and the most favorable prospect of the Upper Palaeozoic will be the central axis to the west of Hidden fault I where three gas bearing reservoirs will be possibly explored at the same time.
基金Petro China-Southwest Petroleum University Innovation Consortium Science and Technology Cooperation Project(2020CX010000)。
文摘Based on comprehensive analysis of cores,thin sections,logging and seismic data,the sequence stratigraphy and sedimentary evolution of the third and fourth members of Sinian Dengying Formation(Deng 3 and Deng 4 members for short)in the Gaomo area of Sichuan Basin were investigated,and the favorable zones for reservoir development in the Deng 3 Member and Deng 4 Member were predicted.(1)Two Type I and one Type II sequence boundaries are identified in the Deng 3 and Deng 4 members.Based on the identified sequence boundaries,the Deng 3 and Deng 4 members can be divided into two third order sequences SQ3 and SQ4,which are well-developed,isochronal and traceable in this area;the SQ3 thins from west to the east,and the SQ4 thins from northwest to southeast.(2)The sedimentary environment from the depositional period of SQ3 to SQ4 has experienced the evolution from mixed platform to rimmed platform,and the platform rimmed system on the west side is characterized by the development of platform margin microbial mound and grain shoal assemblages.The intraplatform area is a restricted platform facies composed of a variety of dolomites,and there are local micro-geomorphic highlands of different scales and scattered intraplatform mounds and shoals.(3)The Deng 4 Member reservoirs,with obvious facies-controlled characteristic,are mainly distributed in the upper part of high-frequency upward shallow cycle and the high-stand systems tract of the third-order sequence vertically,and are more developed in the platform margin belt than in the intraplatform belt,and more developed in the Gaoshiti platform margin belt than in the west Suining platform margin belt on the plane.(4)Three types of favorable reservoir zones of Deng 4 Member have been finely delineated with 3D seismic data;among them,the mound and shoal facies zones developed in the ancient highlands of the intraplatform are the first choice for the next exploration and development of the Deng 4 Member.
