页岩储层孔隙结构与分形特征演化规律  

Pore structures in shale reservoirs and evolution laws of fractal characteristics

作　　者：吴伟 梁志凯 郑马嘉 姜振学[2,3] 郭婕 薛子鑫 王孟 WU Wei;LIANG Zhikai;ZHENG Majia;JIANG Zhenxue;GUO Jie;XUE Zixin;WANG Meng(Shale Gas Research Institute,PetroChina Southwest Oil&Gasfield Company,Chengdu City,Sichuan Province,610051,China;State Key Laboratory of Petroleum Resources and Prospecting,China University of Petroleum(Beijing),Beijing City,102249,China;Unconventional Petroleum Research Institute,China University of Petroleum(Beijing),Beijing City,102249,China;Sichuan Changning Natural Gas Development Co.,Ltd.,Chengdu City,Sichuan Province,610051,China)

机构地区：[1]中国石油西南油气田公司页岩气研究院,四川成都610051 [2]中国石油大学(北京)油气资源与探测国家重点实验室,北京102249 [3]中国石油大学(北京)非常规油气科学技术研究院,北京102249 [4]四川长宁天然气开发有限责任公司,四川成都610051

出　　处：《油气地质与采收率》2022年第4期35-45,共11页Petroleum Geology and Recovery Efficiency

基　　金：国家自然科学基金项目“海相富气页岩低阻成因及其对含气性的控制机理”(42072151);国家科技重大专项“五峰-龙马溪组富有机质页岩储层精细描述与页岩气成藏机理”(2017ZX05035-02)。

摘　　要：为了研究页岩储层演化对其分形维数的影响,以鄂尔多斯盆地延长组低成熟度陆相页岩、松辽盆地沙河子组高成熟度陆相页岩、川南地区龙马溪组高—过成熟度海相页岩为例,利用X射线衍射分析、地球化学分析、氮气吸附实验等手段,结合FHH与热力学模型,研究不同分形维数的演化特征,利用灰色关联系数法分析不同演化阶段分形维数的控制因素。结果表明:低成熟度陆相页岩分形维数较低,高成熟度海相、陆相页岩具有较高的分形维数。高—过成熟度海相页岩中,较高的孔表面积与孔体积会造成孔隙复杂程度明显增高,但这种关系在低成熟度陆相页岩并不明显,可能是滞留烃造成微孔阻塞或覆盖孔隙表面,使分形维数下降。随着演化程度的增加,页岩储层分形维数的主要影响因素逐渐从矿物组成变成总有机碳含量。This study is conducted to explore the influence of the evolution of shale reservoirs on their fractal dimensions.Specifically,three examples are selected for the case study,namely,the terrestrial shale with low maturity of Yanchang For⁃mation in Erdos Basin,the terrestrial shale with high maturity of Shahezi Formation in Songliao Basin,and the marine shale with high and excessive maturity of Longmaxi Formation in the southern Sichuan region.On this basis,the evolution characteristics of different fractal dimensions are studied by means including X-ray diffraction(XRD),geochemical analysis,and nitrogen adsorption experiments in combination with the Frenkel-Halsey-Hil(FHH)and thermodynamic models.Moreover,the grey relational analysis(GRA)was performed to analyze the controlling factors of fractal dimensions in different evolution phases.The results reveal that the terrestrial shale with low maturity has low fractal dimensions,whereas the terrestrial and marine shale with high maturity has high dimensions.In the marine shale evolved from high maturity to exces⁃sive maturity,a high pore volume and surface area have a significantly positive relationship with the pore complexity,but this relationship is not prominent in the terrestrial shale with low maturity.The reason might be that the occluded hydrocarbon causes micropore blocking or covers the surface of pores,which reduces the fractal dimensions.As the evolution increases,the main influencing factor of the fractal dimensions of shale reservoirs gradually changes from the mineral compositions to the total organic carbon(TOC).

关 键 词：页岩 分形特征 孔隙结构 龙马溪组 延长组 沙河子组 

分 类 号：TE122.23[石油与天然气工程—油气勘探]