Influences of lithofacies on fluid mobility in mixed sedimentary rocks:Insights from NMR analysis of the middle Permian Lucaogou Formation,Junggar Basin  

作　　者：Huricha Wu Yaohua Wang Jingqiang Tan Xiao Ma Ruining Hu Wenhui Liu 

机构地区：[1]Key Laboratory of Metallogenic Prediction of Nonferrous Metals and Geological Environment Monitoring,School of Geosciences and Info-physics,Central South University,Changsha,410083,China

出　　处：《Energy Geoscience》2024年第4期108-124,共17页能源地球科学（英文）

基　　金：supported by the Development Project of Xinjiang Conglomerate Reservoir Laboratory(Grant No.2020D04045).

摘　　要：The multi-source mixed sedimentation resulted in a unique series of mixed fine-grained sedimentary rocks evolved within the Permian Lucaogou Formation in the Jimusar Sag,located in the southeastern Junggar Basin,China.The variety of lithofacies within this series resulted in pronounced heterogeneity of pore structures,complicating the analysis of fluid occurrence space and state within reservoirs.As a result,the impact of lithofacies on fluid mobility remains ambiguous.In this study,we employed qualitative methods,such as field emission scanning electron microscopy(FE-SEM)and thin section observation,and quantitative analyses,including X-ray diffraction(XRD),total organic carbon(TOC),vitrinite reflectance(Ro),high-pressure mercury intrusion(HPMI)porosimetry,and nuclear magnetic resonance(NMR),along with linear and grey correlation analyses.This approach helped delineate the effective pore characteristics and principal factors influencing movable fluids in the fine-grained mixed rocks of the Lucaogou Formation in the Jimusar Sag,Junggar Basin.The findings indicate the development of three fundamental lithologies within the Lucaogou Formation:fine sandstone,siltstone,and mudstone.Siltstones exhibit the highest movable fluid saturation(MFS),followed by fine sandstones and mudstones sequentially.Fluid mobility is predominantly governed by the content of brittle minerals,the sorting coefficient(Sc),effective pore connectivity(EPC),and the fractal dimension(D_(2)).High content of brittle minerals favors the preservation of intergranular pores and the generation of microcracks,thus offering more occurrence space for movable fluids.A moderate Sc indicates the presence of larger connecting throats between pores,enhancing fluid mobility.Elevated EPC suggests more interconnected pore throat spaces,facilitating fluid movement.A higher D_(2)implies a more intricate effective pore structure,increasing the surface area of the rough pores and thereby impeding fluid mobility.Ultimately,this study developed a conceptual model that

关 键 词：Multi-source mixed sedimentation Movable fluid Permian lucaogou formation Nuclear magnetic resonance Grey correlation analysis 

分 类 号：P588.2[天文地球—岩石学] TE311[天文地球—地质学]