气藏抬升过程中孔隙结构差异特征及演化模式——以四川盆地及周缘五峰组—龙马溪组页岩储层为例  

Pore structure difference characteristics and evolution model in the process of gas reservoir uplift:A case study of the shale reservoir of Wufeng Formation-Longmaxi Formation in Sichuan basin and its surrounding areas

作　　者：王丹丹[1,2] 姜振学[1,2] 杜威 刘达东 陈文逸 杨宇 冯霞 WANG Dandan;JIANG Zhenxue;DU Wei;LIU Dadong;CHEN Wenyi;YANG Yu;FENG Xia(National Key Laboratory of Petroleum Resources and Engineering,China University of Petroleum(Beijing),Beijing 102249,China;Unconventional Petroleum Research Institute,China Universityof Petroleum(Beijing),Beijing 102249,China;Guizhou Instituteof Petroleum Exploration and Development Engineering,Guiyang,Guizhou 550000,China)

机构地区：[1]油气资源与工程全国重点实验室,中国石油大学(北京),北京102249 [2]非常规油气科学技术研究院,中国石油大学(北京),北京102249 [3]贵州省油气勘查开发工程研究院,贵州贵阳550000

出　　处：《地质学报》2025年第4期1381-1397,共17页Acta Geologica Sinica

基　　金：国家自然科学基金项目(编号U24A20592,42072151)资助的成果。

摘　　要：岩相和超压是影响储层孔隙结构最重要的因素,但二者谁更占据主导作用存在较大争议,导致气藏抬升过程中孔隙结构差异特征及演化模式尚不清楚。以四川盆地及周缘五峰组—龙马溪组页岩为研究对象。通过矿物组成、有机地球化学分析、场发射扫描电镜观察、数字图像处理与提取、全孔径表征(CO_(2)、N_(2)和高压压汞)等方法,探讨了页岩气藏最大埋深后抬升过程中岩相及超压对页岩孔隙结构的影响作用,并建立了气藏抬升过程中页岩孔隙演化模式。研究结果表明:(1)同一压力区富有机质硅质页岩较贫有机质黏土质页岩具有更大的孔隙比表面积、孔隙体积及分形维数,TOC相对于黏土矿物对孔隙比表面积和孔隙体积影响更大;(2)不同压力区富有机质硅质页岩相抬升时期晚,抬升幅度小的页岩具有更大的孔隙比表面积、孔隙体积、圆度系数和分形维数,超压对孔隙具有保持作用,孔隙免遭压实而变形程度小;(3)岩相对页岩孔隙比表面积的影响主要体现在微孔,而超压对页岩孔隙孔体积的影响主要体现在介孔和宏孔。建立了气藏抬升过程中页岩石英抗压保孔和储层超压保孔模式。本研究成果可以丰富页岩气成藏机制的再认识,对页岩气储层保存及破坏评价具有重要意义。Lithofacies and overpressure are the most important factors affecting the pore structure of the reservoir.However,the relative dominance of these factors remains debated,leading to variations in the characteristics and evolutionary models of pore structure during the uplift process of gas reservoirs.This study focuses on the shale of the Wufeng Formation-Longmaxi Formation in the Sichuan basin and its surrounding areas as the research subject.By analyzing mineral composition,organic geochemistry,field emission scanning electron microscopy,digital image processing and extraction,and full-aperture pore characterization(CO_2,N_2,and high-pressure mercury intrusion),the effects of lithofacies and overpressure on shale pore structure during the uplift process after reaching maximum burial depth were investigated.Additionally,an evolutionary model of shale pores during gas reservoir uplift was established.The results reveal the following:(1) Organic-rich siliceous shale exhibits a larger pore-specific surface area,pore volume,and fractal dimension compared to organic-poor clay shale in the same pressure zone.(2) Organic-rich siliceous shale in different pressure zones experienced a later uplift period and a smaller uplift range.It demonstrates a larger specific surface area,pore volume,roundness coefficient,and fractal dimension.Overpressure has a maintaining effect on pores,preventing compaction and minimizing deformation.(3) The influence of lithofacies on shale pore-specific surface is mainly observed in micropores,while overpressure predominantly affects pore volume in mesopores and macropores.Based on these findings,models of shale quartz compressive pore-preserving and reservoir overpressure pore-preserving during gas reservoir uplift were established.This study enhances the understanding of shale gas accumulation mechanisms and is of great significance for evaluating shale gas reservoir preservation and potential damage.

关 键 词：岩相 构造抬升 储层孔隙结构 四川盆地及周缘 五峰组—龙马溪组页岩 

分 类 号：P618.13[天文地球—矿床学]