岩相组合特征及其对页岩含气性的影响
——以涪陵地区凉高山组为例

Characteristics of lithofacies combinations and its influence on shale gas-bearing property: a case study of the Lianggaoshan Formation in Fuling area

刘苗苗 付小平 倪楷

中国石化勘探分公司，四川 成都 610041

SINOPEC Exploration Company, Chengdu 610041, China

陆相页岩非均质性强，为了查明涪陵地区凉高山组不同岩相组合对页岩含气性的影响，文中基于岩心照片、普通薄片、X衍射、有机质丰度等分析化验资料开展了岩相评价，通过扫描电镜、等温吸附、现场含气量测试等实验，分析了6种岩相组合的孔隙结构和含气性。研究表明：凉高山组发育高碳纹层状页岩夹粉砂岩、中碳纹层状—层状页岩夹粉砂岩、中碳层状页岩夹粉砂岩、含碳块状泥岩夹粉砂岩、中低碳层状泥岩与粉砂岩互层、低碳层状粉砂岩夹泥岩6种岩相组合类型；不同岩相的孔隙度、孔径分布特征主要受层理缝、有机质丰度的影响，比表面积则受黏土矿物成分、有机质丰度及微裂缝的共同影响；明确了高碳纹层状页岩夹粉砂岩是研究区优势岩相组合，在研究区内广泛分布。研究成果可为页岩油气富集预测提供技术支撑，为涪陵地区凉高山组页岩油气下步勘探指明方向。

Continental shale reservoirs has strong heterogeneity. In order to find out the influence of different lithofacies combinations of Lianggaoshan Formation in Fuling area on shale gas-bearing property, the lithofacies evaluation is carried out based on the analysis and test data of core photograph, ordinary thin section, X-ray diffraction and organic matter abundance. The pore structure and gas-bearing property of six lithofacies combinations are analyzed by means of scanning electron microscope, isothermal adsorption experiment and in-situ gas content test. The research shows that six kinds of lithofacies such as high carbon laminated mudstone with siltstone, medium carbon laminated-bedded mudstone with siltstone, medium carbon bedded mudstone with siltstone, carbon-bearing massive mudstone with siltstone, medium-low carbon bedded mudstone with siltstone interbedded, low carbon bedded siltstone with mudston are developed. The porosity and pore size distribution of different lithofacies are mainly influenced by bedding fractures and organic matter abundance, the specific surface area is affected by clay mineral composition, organic matter abundance and micro-fracture. The high carbon laminated mudstone with siltstone is the favorable lithofacies combination in Fuling area, and it is widely distributed in the study area. The results can provide the basis for enrichment prediction and point out the direction for oil and gas exploration of Lianggaoshan Formation in Fuling area.

10.6056/dkyqt202301001