Sand body architecture of braided river deltas in the Upper Triassic Xujiahe Formation, Sichuan Basin  

作　　者：Yanqing Huang Meizhou Deng Nan Duan Wujun Jin Junlong Liu Na Niu Ai Wang Xiaolin Lu 

机构地区：[1]Petroleum Exploration and Production Research Institute,SINOPEC,Beijing,100083,China [2]Southwest Oil&Gas Branch Company,SINOPEC,Chengdu,610095,China

出　　处：《Energy Geoscience》2025年第1期89-100,共12页能源地球科学(英文)

基　　金：funded by a SINOPEC project entitled Exploration Potential and Target Evaluation of Xujiahe Formation in the Northeastern Sichuan Basin(No.P23130).

摘　　要：The recent discovery of natural gas within the fifth member of the Xujiahe Formation(T_(3)x_(5))in the Dongfeng area within the Sichuan Basin highlights the significant exploration potential of this member.However,the unconvincing previous understanding of the sedimentary microfacies,combined with a total lack of studies on the sand body architecture and reservoir distribution,hampers the further exploration of this member.Using core data,log curves,and seismic data,along with sedimentary microfacies analysis,this study investigated the interfaces between the sand bodies of various scales in the Dongfeng area.Furthermore,this study explored the morphological characteristics,types,and stacking patterns of these sand bodies and determined the distributions of sand bodies and reservoirs in the area.The results indicate that the first sand group of the T_(3)x_(5) member(T_(3)x^(1)_(5))exhibits delta-front deposits,including subaqueous distributary channels,sheet sands,and interdistributary bays.Seven levels of sand body interfaces are identified in the T_(3)x^(1)_(5) sand group.Among them,the interfaces of the first and second levels were identifed only in cores,those of the third and fourth levels were recog-nizable from cores combined with log curves,while those of the fifth,sixth,and seventh levels were distinguishable using seismic data.Three superimposed subaqueous distributary channel complexes are found in the Dongfeng area.Among them,complex 1 in the northwest exhibits the strongest water body energy,while complex 2 in the south displays the weakest.Complex 2 was formed earlier than com-plexes 1 and 3.Also,complex 1 is further subdivided into three vertically stacked subaqueous distrib-utary channels.The subdivision of sedimentary microfacies in the T_(3)x_(5) member reveals nine lithofacies types.Among them,stacked pancake-shaped,carbonaceous debris-bearing,massive,and cross-bedded medium-grained sandstones are considered favorable lithofacies.These four lithofacies types exhibit high porosity,as well as low

关 键 词：Sand body architecture Favorable lithofacies Xujiahe Formation Upper Triassic Sichuan Basin 

分 类 号：P61[天文地球—矿床学]