四川盆地东北部下侏罗统自流井组陆相页岩储层孔隙特征及形成控制因素

Pore characteristics and controlling factors of continental shale reservoirs in the Lower Jurassic Ziliujing Formation, northeastern Sichuan Basin

刘忠宝 胡宗全 刘光祥 刘珠江 刘晧天 郝景宇 王鹏威 李鹏

Zhongbao Liu Zongquan Hu Guangxiang Liu Zhujiang Liu Haotian Liu Jingyu Hao Pengwei Wang Peng Li

为查明川东北自流井组陆相富有机质页岩储层孔隙发育特点及形成机理，采用岩石薄片、全岩X-衍射、有机岩石学、高压压汞-吸附联合测定、氩离子抛光-扫描电镜及物性测试等多种技术方法，开展了川东北地区自流井组陆相页岩储层孔隙结构、类型及储集性能研究，并探讨了主要孔隙类型的形成控制因素。研究结果表明：川东涪陵地区东岳庙段和川北元坝地区大安寨段页岩平均孔隙度均大于4%，储集性能较好，页岩孔隙类型主要以无机矿物质孔为主，其次为有机质孔，局部发育微裂缝，无机矿物质孔对孔隙度的贡献最大。页岩粘土矿物含量及压实作用的强弱控制了无机矿物质孔的发育程度，有机质组分类型是控制有机质孔发育与否的关键因素，表现为固体沥青内普遍发育有机质孔，而大多数镜质体内基本不发育有机质孔。川东涪陵地区东岳庙段与大安寨段、川北元坝地区大安寨段无机矿物质孔与有机质孔均有发育，而川北元坝地区东岳庙段仅发育无机矿物质孔，有机质孔基本不发育。

The development characteristics and mechanisms of pores in the organic-rich continental shale in the Ziliujing Formation of the Yuanba and Fuling areas, northeastern Sichuan Basin, were studied based on an integration of thin-section observation, whole-rock x-ray diffraction and organic matter petrological analyses with measurements obtained jointly through high-pressure mercury intrusion and adsorption experiments, and argon ion polishing-scanning electron microscopy and physical property tests.As a result, the structure, type and storage capacity of the pores as well as the factors controlling the pore growth were revealed.It shows that both the Dongyuemiao Member shale in the Fuling area of eastern Sichuan Basin and Da'anzhai Member shale in the Yuanba area of northern Sichuan Basin have high reservoir capacity with an average porosity higher than 4%.Pores in the shales are mostly inorganic mineral pores, followed by organic-matter pores and some local micro-cracks.The inorganic mineral pores show signs of strong influence of clay mineral and compaction intensity.And the organic-matter pores were probably conditioned by the composition type of organic matter as they are found to be abundant in solid asphalt, but rare in most vitrinites.The Dongyuemiao and Da'anzhai Members of the Fuling area in eastern Sichuan Basin and the Da'anzhai Member of the Yuanba area in northern Sichuan Basin contain both types of pores, while the Dongyuemiao Member of the Yuanba area is rich in inorganic mineral pores only.

10.11743/ogg20210112