Gravity flows in steep-slope zones of lacustrine rift basins interact with deep-water shales to form heterogeneous mixed sedimentation zones,yet their sedimentary evolution and hydrocarbon occurrence characteristics r...Gravity flows in steep-slope zones of lacustrine rift basins interact with deep-water shales to form heterogeneous mixed sedimentation zones,yet their sedimentary evolution and hydrocarbon occurrence characteristics remain poorly understood.In this study,core and thin section observations,X-ray diffraction,scanning electron microscopy,mercury intrusion porosimetry,low-pressure nitrogen physisorption,total organic carbon testing,step-by-step Rock-Eval pyrolysis,and time series analysis,were conducted to decode sedimentology and hydrocarbon occurrence characteristics based on lithofacies combinations controlled by astronomical cycles.Results reveal five microfacies(calcareous/felsic semi-deep lake,outer fan,channel front,braided channel)and six lithofacies combinations(LC1-LC6)shaped by debris flows,turbidity currents,and felsic mixed floating currents.The 406-kyr long eccentricity cycle governs sediment supply and reservoir heterogeneity.During high eccentricity phases,increased monsoon-driven terrigenous input enhances sandstone deposition,developing braided channel(LC5)and channel front(LC6)microfacies.These intervals exhibit elevated terrigenous quartz/feldspar content and reduced organic carbon in fine-grained sedimentary rocks,with hydrocarbons occurring as quasi-continuous to discontinuous accumulations.Conversely,during low eccentricity phases,felsic mineral layers or isolated sandstone interlayers dominate,forming outer fan(LC3),channel front(LC4),and semi-deep lake(LC1-LC2)microfacies.These intervals show lower terrigenous content and higher TOC in fine-grained sedimentary rocks,with hydrocarbons occurring as continuous to quasi-continuous accumulations.A novel sedimentary evolution and hydrocarbon occurrence model demonstrates the ordered coexistence of conventional and unconventional reservoirs,driven by astronomically forced climate fluctuations.This framework advances theoretical understanding and optimizes exploration strategies for steep-slope lacustrine basins with mixed sedimentation.展开更多
页岩气储层的气水两相渗流能力对其产能有着重要影响,但尚无直接通过测井等地球物理手段评价页岩气流动能力的方法。目前已通过岩心聚焦离子束-扫描电镜(Focused Ion Beam-Scanning Electron Microscope,FIB-SEM)扫描建立页岩无机孔隙...页岩气储层的气水两相渗流能力对其产能有着重要影响,但尚无直接通过测井等地球物理手段评价页岩气流动能力的方法。目前已通过岩心聚焦离子束-扫描电镜(Focused Ion Beam-Scanning Electron Microscope,FIB-SEM)扫描建立页岩无机孔隙、有机孔隙和微裂缝的三维数字岩心模型,基于流体体积法(Volume of Fluid,VOF)开展了不同润湿条件下的页岩孔缝结构气驱水渗流模拟并得到了端点含水饱和度等特征。该文基于模拟结果得到的不同孔隙类型流动能力的认识,结合大面积拼接扫描电镜(Modular Automated Processing System,MAPS)中提取的不同类型的孔隙统计,获得了每块岩心的等效流动能力。将岩心的等效流动能力与岩石物理实验和测井响应进行综合分析,提出了无量纲渗流能力的概念,建立了基于测井资料评价流动能力的模型。实际测井资料处理结果表明,所提出的评价模型具有较高的准确度,可以获得连续的页岩气流动能力剖面,可用于指导页岩气勘探开发。展开更多
基金funded by Oil&Gas Major Project of China(Grant No.2024ZD1405102)National Natural Science Foundation of China(Grant No.42172153)+1 种基金Xinjiang Key Research and Development Program(No.2024B03007)Youth Innovation and Technology Support Program for Shandong Provincial Universities(Grant No.2022KJ066).
文摘Gravity flows in steep-slope zones of lacustrine rift basins interact with deep-water shales to form heterogeneous mixed sedimentation zones,yet their sedimentary evolution and hydrocarbon occurrence characteristics remain poorly understood.In this study,core and thin section observations,X-ray diffraction,scanning electron microscopy,mercury intrusion porosimetry,low-pressure nitrogen physisorption,total organic carbon testing,step-by-step Rock-Eval pyrolysis,and time series analysis,were conducted to decode sedimentology and hydrocarbon occurrence characteristics based on lithofacies combinations controlled by astronomical cycles.Results reveal five microfacies(calcareous/felsic semi-deep lake,outer fan,channel front,braided channel)and six lithofacies combinations(LC1-LC6)shaped by debris flows,turbidity currents,and felsic mixed floating currents.The 406-kyr long eccentricity cycle governs sediment supply and reservoir heterogeneity.During high eccentricity phases,increased monsoon-driven terrigenous input enhances sandstone deposition,developing braided channel(LC5)and channel front(LC6)microfacies.These intervals exhibit elevated terrigenous quartz/feldspar content and reduced organic carbon in fine-grained sedimentary rocks,with hydrocarbons occurring as quasi-continuous to discontinuous accumulations.Conversely,during low eccentricity phases,felsic mineral layers or isolated sandstone interlayers dominate,forming outer fan(LC3),channel front(LC4),and semi-deep lake(LC1-LC2)microfacies.These intervals show lower terrigenous content and higher TOC in fine-grained sedimentary rocks,with hydrocarbons occurring as continuous to quasi-continuous accumulations.A novel sedimentary evolution and hydrocarbon occurrence model demonstrates the ordered coexistence of conventional and unconventional reservoirs,driven by astronomically forced climate fluctuations.This framework advances theoretical understanding and optimizes exploration strategies for steep-slope lacustrine basins with mixed sedimentation.
文摘页岩气储层的气水两相渗流能力对其产能有着重要影响,但尚无直接通过测井等地球物理手段评价页岩气流动能力的方法。目前已通过岩心聚焦离子束-扫描电镜(Focused Ion Beam-Scanning Electron Microscope,FIB-SEM)扫描建立页岩无机孔隙、有机孔隙和微裂缝的三维数字岩心模型,基于流体体积法(Volume of Fluid,VOF)开展了不同润湿条件下的页岩孔缝结构气驱水渗流模拟并得到了端点含水饱和度等特征。该文基于模拟结果得到的不同孔隙类型流动能力的认识,结合大面积拼接扫描电镜(Modular Automated Processing System,MAPS)中提取的不同类型的孔隙统计,获得了每块岩心的等效流动能力。将岩心的等效流动能力与岩石物理实验和测井响应进行综合分析,提出了无量纲渗流能力的概念,建立了基于测井资料评价流动能力的模型。实际测井资料处理结果表明,所提出的评价模型具有较高的准确度,可以获得连续的页岩气流动能力剖面,可用于指导页岩气勘探开发。
