Geological Characteristics and Their Coupling Relationship between Structural Evolution and Reservoir Formation of Paleozoic Oil Reservoirs in the Southern Section of the Western Edge of the Ordos Basin
Wei Jiayi
Zhang Lei
Wang Hongwei
Cao Qian
Jing Xianghui
Yang Yajuan
Zhang Yan
Liu Gang
Li Han
Abstract：Based on the geological,seismic,and analytical data obtained from the exploration of Paleozoic oil reservoirs in the southern section of the western margin thrust belt in the Ordos basin and based on the first Paleozoic industrial oil flow Well YT3 discovered in 2022,combined with the tectonic sedimentary background of the Wulalike Formation and Yanghugou Formation oil-bearing series,this study conducts a comparison of Paleozoic oil sources,quantitatively restores the structural evolution process,systematically analyzes the genesis and reservoir-structure coupling relationship of Paleozoic oil reservoirs,constructs unconventional oil reservoir accumulation models,predicts and evaluates favorable exploration areas.The study shows follows.(1)The crude oil of the Lower Paleozoic Wulalike Formation is"single source"from the same layer of mudstone source rocks,and the oil sand of the Upper Paleozoic Yanghugou Formation is"dual source",contributing to the joint contribution of the Wulalike Formation mudstone source rocks and the Yanghugou Formation coal-bearing source rocks.Both sets of source rocks have the ability to generate oil,and in comparison,the Wulalike Formation source rocks have a greater potential for oil generation.(2)The construction quantitative restoration of the balanced profile method reveals that the differential settlement effect during the Hercynian-Indosinian period is the fundamental reason for the differences in maturity of the source rocks of the Wulalike Formation in the Yindongzi and Shajingzi thrust faults,which is high in the west and low in the east,as well as the differences in oil and gas phases.(3)A"dual source and dual storage"stereoscopic reservoir formation model of unconventional oil reservoirs is constructed through the study of source and reservoir configuration relationship.The Wulalike Formation has developed"self generating and self storing"oil reservoirs,while the Yanghugou Formation has developed"bottom generating and upper storing"and"source in"oil reservoirs.(4)The geological seismic multi-attribute fusion prediction area has a favorable exploration area of 400 km2 for the Wulalike Formation shale and 300 km2 for the Yanghugou Formation.The volume method estimates the total resource potential of the Upper and Lower Paleozoic oil reservoirs in the southern section of the western margin to be 1.0×108 t,which is a realistic target replacement area for Paleozoic reservoir exploration.
Keywords：Ordos basinPaleozoic oil reservoirsWulalike Formation crude oilYanghugou Formation oil sandquantitative structural evolutiondual source and dual storagetectonicspetroleum geology
Publication Date：2025-05-30
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：20( 1933-1952 )