鄂尔多斯盆地西缘奥陶系乌拉力克组海相页岩气储层甜点分类评价

Classification and evaluation of sweet spots of marine shale gas reservoir in Ordovician Wulalike Formation on the westen margin of Ordos Basin

张琳琳 王孔杰 赖枫鹏 郭伟 苗丽丽

ZHANG Linlin WANG Kongjie LAI Fengpeng GUO Wei MIAO Lili

1. 中国地质大学(北京) 能源学院, 北京 100083; 2. 非常规天然气能源地质评价与开发工程北京市重点实验室, 北京 100083; 3. 中国石油 川庆钻探工程有限公司 长庆井下技术作业公司, 西安 710016; 4. 中国石油 长城钻探工程有限公司 地质研究院, 辽宁 盘锦 124010; 5. 中国地质大学(北京), 北京 100083

1. School of Energy, China University of Geosciences (Beijing), Beijing 100083, China; 2. Beijing Key Laboratory of Unconventional Natural Gas Energy Geological Evaluation and Development, Beijing 100083, China; 3. Changqing Downhole Technology Operation Company, CNPC Chuanqing Drilling Engineering Co., Ltd., Xi'an, Shaanxi 710016, China; 4. Geology Research Institute of GWDC, PetroChina, Panjin, Liaoning 124010, China; 5. China University of Geosciences (Beijing), Beijing 100083, China

甜点评价对页岩气藏高效勘探开发具有重要意义。以鄂尔多斯盆地西缘奥陶系乌拉力克组页岩储层为研究对象，通过岩石薄片分析、X射线衍射、SEM扫描电镜、低温氮气吸附、等温吸附、总有机碳(TOC)含量、有机质镜质体反射率(Ro)测试和三轴岩石力学测试8个实验，得到目标区岩石类型为灰褐色泥页岩，孔径集中分布在2～4 nm和35～61 nm，主要发育粒间孔、黏土矿物层间孔和粒内孔；总有机碳含量平均为1.01%，Ro值平均为1.75%，脆性指数平均为47.8%。通过分析不同因素对页岩储层甜点区评选及评价的影响，认为硅质矿物含量、黏土矿物含量、孔比表面积、总有机碳含量和Ro值对储层的吸附性能起决定作用，孔径大小和孔隙类型数量控制储层的储集性能，脆性矿物含量和岩石力学参数影响储层的可压性。根据地质甜点评价的吸附性能和储集性能两个指标以及工程甜点的可压性指标，完成了不同特征对应的参数指标细分类，初步建立了鄂尔多斯盆地西缘奥陶系乌拉力克组海相页岩气储层3个等级的地质甜点和可压性甜点的分类评价方案，结果表明目标区各特征参数均达到Ⅱ级标准，可以作为页岩气开发甜点区。

Sweet spot evaluation is of great significance for efficient exploration and development of shale gas reservoirs. Taking the shale reservoir in Ordovician Wulalike Formation on the western margin of the Ordos Basin as the research object, eight experiments including rock section analysis, X-ray diffraction, SEM scanning electron microscopy, low-temperature nitrogen adsorption, isothermal adsorption, total organic carbon (TOC) content test, organic matter vitrinite reflectance (Ro) test and triaxial rock mechanics test were carried out in this study. It is found that the rock type in the target area is gray brown mud shale, with the pore size in the ranges of 2-4 nm and 35-61 nm, and intergranular pores, clay mineral interlayer pores and intragranular pores are developed. The TOC content is 1.01%, the average Ro value is 1.75%, and the brittleness index is 47.8%. By analyzing the influence of different factors on the selection and evaluation of shale reservoir sweet spots, it is concluded that the content of siliceous minerals, clay minerals, pore specific surface area, TOC content and Ro value play a decisive role on the adsorption perfor-mance of the reservoir, the pore size and the number of pore types control the reservoir property, the content of brittle minerals and rock mechanics parameters affect the compressibility of the reservoir. According to the two indexes of adsorption property and reservoir property evaluated by geological sweet spots and the compressibility index of engineering sweet spots, the parameter indexes corresponding to different characteristics are finely classified, and a classification and evaluation scheme of geological sweet spots and compressibility sweet spots of the marine shale gas reservoir in Ordovician Wulalike Formation in the Ordos Basin is preliminarily established. The results show that all characteristic para-meters in the target area meet the grade Ⅱ standard. It could be a sweet spot for shale gas development.

国家自然科学基金项目“页岩油藏CO2复合压裂渗吸—渗流机理及排采制度优化研究”(52174037)资助。

https://doi.org/10.11781/sysydz202401191