Based on the seismic, logging, drilling and other data, the distribution, structural types and mound-shoal hydrocarbon accumulation characteristics of platform margins of the Sinian Dengying Formation in the Deyang-An...Based on the seismic, logging, drilling and other data, the distribution, structural types and mound-shoal hydrocarbon accumulation characteristics of platform margins of the Sinian Dengying Formation in the Deyang-Anyue Rift and its periphery were analyzed. Four types of platform margins are developed in the Dengying Formation, i.e., single-stage fault-controlled platform margin, multi-stage fault-controlled platform margin, gentle slope platform margin, and overlapping platform margin. In the Gaoshiti West-Weiyuan East area, single-stage fault controlled platform margins are developed in the Deng 2 Member, which trend in nearly NEE direction and are shielded by faults and mudstones, forming fault-controlled–lithologic traps. In the Lezhi-Penglai area, independent and multi-stage fault controlled platform margins are developed in the Deng 2 Member, which trend in NE direction and are controlled by synsedimentary faults;the mound-shoal complexes are aggraded and built on the hanging walls of the faults, and they are shielded by tight intertidal belts and the Lower Cambrian source rocks in multiple directions, forming fault-controlled–lithologic and other composite traps. In the Weiyuan-Ziyang area, gentle slope platform margins are developed in the Deng 2 Member, which trend in NW direction;the mound-shoal complexes are mostly thin interbeds as continuous bands and shielded by tight intertidal belts in the updip direction, forming lithologic traps. In the Gaoshiti-Moxi-Yanting area, overlapping platform margins are developed in the Deng 2 and Deng 4 members;the mound-shoal complexes are aggraded and overlaid to create platform margin buildup with a huge thickness and sealed by tight intertidal belts and the Lower Cambrian mudstones in the updip direction, forming large-scale lithologic traps on the north slope of the Central Sichuan Paleouplift. To summarize, the mound-shoal complexes on the platform margins in the Dengying Formation in the Penglai-Zhongjiang area, Moxi North-Yanting area and Weiyuan-Ziyang area are large in scale, with estimated resources of 1.58×1012 m3, and they will be the key targets for the future exploration of the Dengying Formation in the Sichuan Basin.展开更多
Based on outcrop,seismic and drilling data,the main regional unconformities in the Sichuan Basin and their controls on hydrocarbon accumulation were systematically studied.Three findings are obtained.First,six regiona...Based on outcrop,seismic and drilling data,the main regional unconformities in the Sichuan Basin and their controls on hydrocarbon accumulation were systematically studied.Three findings are obtained.First,six regional stratigraphic unconformities are mainly developed in the Sichuan Basin,from the bottom up which are between pre-Sinian and Sinian,between Sinian and Cambrian,between pre-Permian and Permian,between middle and upper Permian,between middle and upper Triassic,and between Triassic and Jurassic.Especially,16 of 21l conventional(and tight)gas fields discovered are believed to have formed in relation to regional unconformities.Second,regional unconformity mainly controls hydrocarbon accumulation from five aspects:(1)The porosity and permeability of reservoirs under the unconformity are improved through weathering crust karstification to form large-scale karst reservoirs;(2)Good source-reservoir-caprock assemblage can form near the unconformity,which provides a basis for forming large gas field;(3)Regional unconformity may lead to stratigraphic pinch-out and rugged ancient landform,giving rise to a large area of stratigraphic and lithologic trap groups;(4)Regional unconformity provides a dominant channel for lateral migration of oil and gas;and(5)Regional unconformity is conducive to large-scale accumulation of oil and gas.Third,the areas related to regional unconformities are the exploration focus of large gas fields in the Sichuan Basin.The pre-Sinian is found with source rocks,reservoir rocks and other favorable conditions for the formation of large gas fields,and presents a large exploration potential.Thus,it is expected to be an important strategic replacement.展开更多
By examining structures,sediments,reservoirs and accumulation assemblages in the Deyang-Anyue rift and its surrounding area,four new understandings are obtained.First,during the initiation period of Deyang-Anyue rift,...By examining structures,sediments,reservoirs and accumulation assemblages in the Deyang-Anyue rift and its surrounding area,four new understandings are obtained.First,during the initiation period of Deyang-Anyue rift,multiple groups of faults developed in the rift due to the effect of tensile force,bringing about multiple mound and shoal belts controlled by horsts in the second member of the Sinian Dengying Formation;in the development stage of the rift,the boundary faults of the rift controlled the development of mound and shoal belts at the platform margin in the fourth member of Dengying Formation;during the shrinkage period of the rift,platform margin grain shoals of the Cambrian Canglangpu Formation developed in the rift margin.Second,four sets of large-scale mound and shoal reservoirs in the second member of Dengying Formation,the fourth member of Dengying Formation,Canglangpu Formation and Longwangmiao Formation overlap with several sets of source rocks such as Qiongzhusi Formation source rocks and Dengying Formation argillaceous limestone or dolomite developed inside and outside the rift,forming good source-reservoir-cap rock combinations;the sealing of tight rock layers in the lateral and updip direction results in the formation model of large lithologic gas reservoirs of oil pool before gas,continuous charging and independent preservation of each gas reservoir.Third,six favorable exploration zones of large-scale lithologic gas reservoirs have been sorted out through comprehensive evaluation,namely,mound and shoal complex controlled by horsts in the northern part of the rift in the second member of Dengying Formation,isolated karst mound and shoal complex of the fourth member of Dengying Formation in the south of the rift,the superimposed area of multi-stage platform margin mounds and shoals of the second and fourth members of Dengying Formation and Canglangpu Formation in the north slope area,the platform margin mounds and shoals of the second and fourth members of Dengying Formation in the west side of the rift,the platform margin mound and shoal bodies of the fourth member of Dengying Formation in the south slope area,etc.Fourth,Well Pengtan-1 drilled on the mound and shoal complex controlled by horsts of the second member of Dengying Formation in the rift and Well Jiaotan-1 drilled on the platform margin mound and shoal complex of the North Slope have obtained high-yield gas flows in multiple target layers,marking the discovery of a new gas province with reserves of(2-3)×10^(12) m^(3).This has proved the huge exploration potential of large lithologic gas reservoir group related to intracratonic rift.展开更多
基金Supported by the Science and Technology Project of PetroChina (2021DJ0605)。
文摘Based on the seismic, logging, drilling and other data, the distribution, structural types and mound-shoal hydrocarbon accumulation characteristics of platform margins of the Sinian Dengying Formation in the Deyang-Anyue Rift and its periphery were analyzed. Four types of platform margins are developed in the Dengying Formation, i.e., single-stage fault-controlled platform margin, multi-stage fault-controlled platform margin, gentle slope platform margin, and overlapping platform margin. In the Gaoshiti West-Weiyuan East area, single-stage fault controlled platform margins are developed in the Deng 2 Member, which trend in nearly NEE direction and are shielded by faults and mudstones, forming fault-controlled–lithologic traps. In the Lezhi-Penglai area, independent and multi-stage fault controlled platform margins are developed in the Deng 2 Member, which trend in NE direction and are controlled by synsedimentary faults;the mound-shoal complexes are aggraded and built on the hanging walls of the faults, and they are shielded by tight intertidal belts and the Lower Cambrian source rocks in multiple directions, forming fault-controlled–lithologic and other composite traps. In the Weiyuan-Ziyang area, gentle slope platform margins are developed in the Deng 2 Member, which trend in NW direction;the mound-shoal complexes are mostly thin interbeds as continuous bands and shielded by tight intertidal belts in the updip direction, forming lithologic traps. In the Gaoshiti-Moxi-Yanting area, overlapping platform margins are developed in the Deng 2 and Deng 4 members;the mound-shoal complexes are aggraded and overlaid to create platform margin buildup with a huge thickness and sealed by tight intertidal belts and the Lower Cambrian mudstones in the updip direction, forming large-scale lithologic traps on the north slope of the Central Sichuan Paleouplift. To summarize, the mound-shoal complexes on the platform margins in the Dengying Formation in the Penglai-Zhongjiang area, Moxi North-Yanting area and Weiyuan-Ziyang area are large in scale, with estimated resources of 1.58×1012 m3, and they will be the key targets for the future exploration of the Dengying Formation in the Sichuan Basin.
基金Supported by the National Natural Science Foundation Project of China(U22B6002)Prospective Basic Technology Research Project of PetroChina(2021DJ0605).
文摘Based on outcrop,seismic and drilling data,the main regional unconformities in the Sichuan Basin and their controls on hydrocarbon accumulation were systematically studied.Three findings are obtained.First,six regional stratigraphic unconformities are mainly developed in the Sichuan Basin,from the bottom up which are between pre-Sinian and Sinian,between Sinian and Cambrian,between pre-Permian and Permian,between middle and upper Permian,between middle and upper Triassic,and between Triassic and Jurassic.Especially,16 of 21l conventional(and tight)gas fields discovered are believed to have formed in relation to regional unconformities.Second,regional unconformity mainly controls hydrocarbon accumulation from five aspects:(1)The porosity and permeability of reservoirs under the unconformity are improved through weathering crust karstification to form large-scale karst reservoirs;(2)Good source-reservoir-caprock assemblage can form near the unconformity,which provides a basis for forming large gas field;(3)Regional unconformity may lead to stratigraphic pinch-out and rugged ancient landform,giving rise to a large area of stratigraphic and lithologic trap groups;(4)Regional unconformity provides a dominant channel for lateral migration of oil and gas;and(5)Regional unconformity is conducive to large-scale accumulation of oil and gas.Third,the areas related to regional unconformities are the exploration focus of large gas fields in the Sichuan Basin.The pre-Sinian is found with source rocks,reservoir rocks and other favorable conditions for the formation of large gas fields,and presents a large exploration potential.Thus,it is expected to be an important strategic replacement.
基金Supported by the National Science and Technology Major Project(2016ZX05007-002)。
文摘By examining structures,sediments,reservoirs and accumulation assemblages in the Deyang-Anyue rift and its surrounding area,four new understandings are obtained.First,during the initiation period of Deyang-Anyue rift,multiple groups of faults developed in the rift due to the effect of tensile force,bringing about multiple mound and shoal belts controlled by horsts in the second member of the Sinian Dengying Formation;in the development stage of the rift,the boundary faults of the rift controlled the development of mound and shoal belts at the platform margin in the fourth member of Dengying Formation;during the shrinkage period of the rift,platform margin grain shoals of the Cambrian Canglangpu Formation developed in the rift margin.Second,four sets of large-scale mound and shoal reservoirs in the second member of Dengying Formation,the fourth member of Dengying Formation,Canglangpu Formation and Longwangmiao Formation overlap with several sets of source rocks such as Qiongzhusi Formation source rocks and Dengying Formation argillaceous limestone or dolomite developed inside and outside the rift,forming good source-reservoir-cap rock combinations;the sealing of tight rock layers in the lateral and updip direction results in the formation model of large lithologic gas reservoirs of oil pool before gas,continuous charging and independent preservation of each gas reservoir.Third,six favorable exploration zones of large-scale lithologic gas reservoirs have been sorted out through comprehensive evaluation,namely,mound and shoal complex controlled by horsts in the northern part of the rift in the second member of Dengying Formation,isolated karst mound and shoal complex of the fourth member of Dengying Formation in the south of the rift,the superimposed area of multi-stage platform margin mounds and shoals of the second and fourth members of Dengying Formation and Canglangpu Formation in the north slope area,the platform margin mounds and shoals of the second and fourth members of Dengying Formation in the west side of the rift,the platform margin mound and shoal bodies of the fourth member of Dengying Formation in the south slope area,etc.Fourth,Well Pengtan-1 drilled on the mound and shoal complex controlled by horsts of the second member of Dengying Formation in the rift and Well Jiaotan-1 drilled on the platform margin mound and shoal complex of the North Slope have obtained high-yield gas flows in multiple target layers,marking the discovery of a new gas province with reserves of(2-3)×10^(12) m^(3).This has proved the huge exploration potential of large lithologic gas reservoir group related to intracratonic rift.
