Characteristics and main controlling factors of intra-platform shoal thin-layer dolomite reservoirs:A case study of Middle Permian Qixia Formation in Gaoshiti-Moxi area of Sichuan Basin,SW China  

作　　者：HE Jiang LIAN Zhihua LUO Wenjun ZHOU Hui XU Huilin HE Puwei Yang Yi LAN Xuemei 

机构地区：[1]School of Geoscience and Technology,Southwest Petroleum University,Chengdu 610500,China [2]Research Institute of Petroleum Exploration and Development,PetroChina Southwest Oil&Gas Field Company,Chengdu 610041,China [3]Research Institute of Petroleum Exploration&Development,PetroChina,Beijing 100083,China

出　　处：《Petroleum Exploration and Development》2024年第1期69-80,共12页石油勘探与开发（英文版）

基　　金：Supported by the National Natural Science Foundation of China(42172177);CNPC Scientific Research and Technological Development Project(2021DJ05);PetroChina-Southwest University of Petroleum Innovation Consortium Project(2020CX020000).

摘　　要：Based on the study of the distribution of intra-platform shoals and the characteristics of dolomite reservoirs in the Middle Permian Qixia Formation in the Gaoshiti–Moxi area of the Sichuan Basin,SW China,the controlling factors of reservoir development were analyzed,and the formation model of“intra-platform shoal thin-layer dolomite reservoir”was established.The Qixia Formation is a regressive cycle from bottom to top,in which the first member(Qi1 Member)develops low-energy open sea microfacies,and the second member(Qi2 Member)evolves into intra-platform shoal and inter-shoal sea with decreases in sea level.The intra-platform shoal is mainly distributed near the top of two secondary shallowing cycles of the Qi2 Member.The most important reservoir rock of the Qixia Formation is thin-layer fractured-vuggy dolomite,followed by vuggy dolomite.The semi-filled saddle dolomite is common in fracture-vug,and intercrystalline pores and residual dissolution pores combined with fractures to form the effective pore-fracture network.Based on the coupling analysis of sedimentary and diagenesis characteristics,the reservoir formation model of“pre-depositional micro-paleogeomorphology controlling shoal,sedimentary shoal controlling dolomite,penecontemporaneous dolomite benefiting preservation of pores,and late hydrothermal action effectively improving reservoir quality”was systematically established.The“first-order high zone”micro-paleogeomorphology before the deposition of the Qixia Formation controlled the development of large area of intra-platform shoals in Gaoshiti area during the deposition of the Qi2 Member.Shoal facies is the basic condition of early dolomitization,and the distribution range of intra-platform shoal and dolomite reservoir is highly consistent.The grain limestone of shoal facies is transformed by two stages of dolomitization.The penecontemporaneous dolomitization is conducive to the preservation of primary pores and secondary dissolved pores.The burial hydrothermal fluid enters the early dolo

关 键 词：Middle Permian Qixia Formation intra-platform shoal thin-layer dolomite paleogeomorphology diagenesis Gaoshiti-Moxi area Sichuan Basin 

分 类 号：P618.13[天文地球—矿床学]