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
This study integrates field outcrop profiles,drilling cores,2D seismic profiles,and 3D seismic data of key areas to analyze the Triassic tectonic-sequence stratigraphy in the Kuqa foreland basin,and investigates the i...This study integrates field outcrop profiles,drilling cores,2D seismic profiles,and 3D seismic data of key areas to analyze the Triassic tectonic-sequence stratigraphy in the Kuqa foreland basin,and investigates the impact of episodic thrust structures on sedimentary evolution and source rock distribution.(1)The Kuqa foreland basin has experienced stages of initial strong,weakened activities,relaxation and inactivity of episodic thrusting,resulting in the identification of 4 second-order sequences(Ehebulake Formation,Karamay Formation,Huangshanjie Formation,Taliqike Formation)and 11 third-order sequences(SQ1-SQ11)in the Triassic strata.Each sequence or secondary sequence displays a“coarse at the bottom and fine at the top”pattern due to the influence of secondary episodic thrust activity.(2)The episodic thrusting is closely linked to regional sequence patterns,deposition and source rock formation and distribution.The sedimentary evolution in the Triassic progresses from fan delta to braided river delta,lake,braided river delta,and meandering river delta,corresponding to the initial strong to the inactivity stages of episodic thrusting.The development stage of thick,coarse-grained sandy conglomerate reservoirs aligns with the strong to weakened thrust activities,while the source rock formation period coincides with the relaxation to inactivity stages.(3)Controlled by the intensity and stages of episodic thrust activity,the nearly EW trending thrust fault significantly thickened the footwall source rock during the Huangshanjie Formation,becoming the development center of Triassic source rock,and experienced multiple overthrust nappes in the soft stratum of the source rock,showing“stacked style”distribution.(4)The deep layers of the Kuqa foreland basin have the foundation and conditions necessary for the formation of substantial gas reservoirs,capable of forming various types of reservoirs such as self-generating and self-storing lithology,lower generating and upper storing fault block-lithology,and stratigraphic unconformity.This area holds significant importance for future gas exploration efforts aimed at enhancing reserves and production capabilities.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 CNPC Major Science and Technology Project(2023ZZ14YJ02)Petro China Science and Technology Major Project(2022KT0201)。
文摘This study integrates field outcrop profiles,drilling cores,2D seismic profiles,and 3D seismic data of key areas to analyze the Triassic tectonic-sequence stratigraphy in the Kuqa foreland basin,and investigates the impact of episodic thrust structures on sedimentary evolution and source rock distribution.(1)The Kuqa foreland basin has experienced stages of initial strong,weakened activities,relaxation and inactivity of episodic thrusting,resulting in the identification of 4 second-order sequences(Ehebulake Formation,Karamay Formation,Huangshanjie Formation,Taliqike Formation)and 11 third-order sequences(SQ1-SQ11)in the Triassic strata.Each sequence or secondary sequence displays a“coarse at the bottom and fine at the top”pattern due to the influence of secondary episodic thrust activity.(2)The episodic thrusting is closely linked to regional sequence patterns,deposition and source rock formation and distribution.The sedimentary evolution in the Triassic progresses from fan delta to braided river delta,lake,braided river delta,and meandering river delta,corresponding to the initial strong to the inactivity stages of episodic thrusting.The development stage of thick,coarse-grained sandy conglomerate reservoirs aligns with the strong to weakened thrust activities,while the source rock formation period coincides with the relaxation to inactivity stages.(3)Controlled by the intensity and stages of episodic thrust activity,the nearly EW trending thrust fault significantly thickened the footwall source rock during the Huangshanjie Formation,becoming the development center of Triassic source rock,and experienced multiple overthrust nappes in the soft stratum of the source rock,showing“stacked style”distribution.(4)The deep layers of the Kuqa foreland basin have the foundation and conditions necessary for the formation of substantial gas reservoirs,capable of forming various types of reservoirs such as self-generating and self-storing lithology,lower generating and upper storing fault block-lithology,and stratigraphic unconformity.This area holds significant importance for future gas exploration efforts aimed at enhancing reserves and production capabilities.
