渤海湾盆地东濮凹陷陆相页岩层系储集特征及其主控因素

Reservoir characteristics and its main controlling factors of continental shale strata in Dongpu Sag， Bohai Bay Basin

徐云龙 张洪安 李继东 张云献 袁波 杨栋栋

中国石化中原油田分公司勘探开发研究院，河南 濮阳 457001 中国石化中原油田分公司，河南 濮阳 457001

Exploration and Development Research Institute, Zhongyuan Oilfield Company, SINOPEC, Puyang 457001, China Zhongyuan Oilfield Company, SINOPEC, Puyang 457001, China)

文中综合运用岩心观察及镜下鉴定、X射线衍射、氩离子抛光扫描电镜、N2吸附￣高压压汞联合测定和微米CT等技术手段，系统地研究了东濮凹陷古近系页岩层系储层岩相发育特征及其储集机理。东濮凹陷古近系页岩层系主要发育纹层状碳酸盐岩￣碳酸盐质岩相、层状黏土岩￣黏土质混合岩相、块状黏土岩￣长英质黏土岩相等3种主要岩相类型，各岩相的储集空间、孔径分布及含油性差异明显。纹层状碳酸盐岩￣碳酸盐质岩相具有较高的有机质丰度（总有机碳质量分数平均为1.65%）；储集空间主要发育层理缝、生烃增压网状缝等宏观裂缝，黏土矿物晶间孔、碳酸盐矿物晶间孔、溶蚀孔、有机质孔等微观孔隙也较发育；以孔径大于20 nm的孔隙为主，中值孔喉半径为145 nm。研究表明：页岩层系中大孔的发育主要受沉积构造和矿物组分中碳酸盐矿物的含量控制，同时，中—高热演化阶段油气生成产生的有机质孔和生烃增压网状缝促进了储集空间的连通性。因此，处于中—高热演化阶段的纹层状碳酸盐岩￣碳酸盐质岩相具有良好的储集空间和较大的孔喉，且含油性较高，是东濮凹陷古近系最有利的页岩油勘探目标。

The data of core observation and microscopic identification, X-ray diffraction, argon ion polishing scanning electron microscope, N2 adsorption-high pressure mercury intrusion combined measurement and micro-CT are comprehensively used to systematically study the lithofacies development characteristics and its storage mechanism of Paleogene shale strata in Dongpu Sag. The Paleogene shale strata in the Dongpu Sag are mainly developed with lamellar carbonate rock-carbonatite lithofacies and layered clay rock-clayey migmatite, and massive clay rock-felsic clay rock. There are obvious differences in the reservoir space, pore size distribution and oil content of each lithofacies. Lamellar carbonate rock-carbonatite lithofacies has high abundance of organic matter （the average of tatol organic carbon content is 1.65%）. The bedding fractures, hydrocarbon-generating pressurized network fractures and other macro-fractures are mainly developed in the reservoir space. The microscopic pores such as intercrystalline pores of clay minerals, intercrystalline pores of carbonate minerals, dissolution pores, organic pores are also relatively developed. The pores with larger pore diameters than 20 nm are mainly developed, and the median pore throat radius is 145 nm. The results show that the development of macropores in shale strata is mainly controlled by the content of carbonate minerals in sedimentary structures and mineral constituent. At the same time, the organic pores and hydrocarbon-generating pressurized network fractures generated by hydrocarbon in the middle-high thermal evolution stage promote the connectivity of the reservoir space. Therefore, the lamellar carbonate rock-carbonatite lithofacies in the middle-high thermal evolution stage have good storage space and large pore throat, and have high oil content, which is the most favorable shale oil exploration target in the Paleogene strata of Dongpu Sag.

10.6056/dkyqt202206002