陆相页岩油储层微观孔喉结构表征与含油性分级评价

Microscopic pore structure characterization and oil-bearing property evaluation of lacustrine shale reservoir： A case study of the Permian Lucaogou Formation in Jimsar Sag， Junggar Basin

王林生 叶义平 覃建华 高阳 邓远 李映艳 肖佃师

Linsheng Wang Yiping Ye Jianhua Qin Yang Gao Yuan Deng Yingyan Li Dianshi Xiao

针对准噶尔盆地吉木萨尔凹陷二叠系芦草沟组页岩油储层类型多样和油层甜点预测难度大的问题，开展页岩油孔隙发育影响机制及含油性分级评价研究。在岩心观察的基础上，应用扫描电镜、压汞和核磁共振等手段，研究吉木萨尔凹陷二叠系芦草沟组页岩油储层的微观孔隙结构，揭示孔隙发育及含油性影响机制，建立油层分类评价标准。结果表明：①芦草沟组发育粒间孔型、粒间-溶蚀-晶间孔型、溶蚀孔型、溶蚀-晶间孔型和晶间孔型5类储层，其中粒间孔型和溶蚀孔型物性及可动性最好，晶间孔型最差。②较高的偏粗组分数量、适中的白云石含量和低胶结物含量共同决定优质储层形成，优质储层分布受近物源、高能环境及古凹的控制。③源-储互层或一体型配置模式含油性好于邻源厚层型，15 nm和70 nm为芦草沟组能否含油及含油性变好的孔喉半径界限。④以孔喉结构与含油性关系为指导，划分出Ⅰ类油层、Ⅱ类油层和Ⅲ类油层。芦草沟组一段二亚段优质储层发育，源-储配置佳，油层甜点分布规模大。研究成果为芦草沟组页岩油油层分类评价及甜点预测提供了地质依据。

In view of the diverse types of shale oil reservoirs and great difficulty in sweet-spot prediction in the Lucaogou Formation， analysis on the mechanism influencing shale oil pore development and evaluation on oil-bearing properties， are supposed to be carried out. To this end， this study focuses on the microscopic pore structure of shale oil reservoirs in the Permian Lucaogou Formation， Jimsar Sag， through an integration of core observation， scanning electron microscopy （SEM）， mercury intrusion porosimetry （MIP） and nuclear magnetic resonance （NMR）， etc. As a result， the influential mechanism is disclosed and classification criteria for reservoir evaluation are set up. The results show that there are five types of reservoirs developed in the Lucaogou Formation： reservoirs of intergranular pore type， of intergranular-dissolved-intercrystalline pore type， of dissolved pore type， of dissolved-intercrystalline pore type and of intercrystalline pore type. Among others， reservoirs of intergranular pore type and dissolved pore type are the best in terms of physical property and mobility， and those of intergranular pore type are the worst. Second， larger amount of coarser grains， proper dolomite content and low level of cement， serve to jointly determine the formation of high-quality reservoirs， the distribution of which is controlled by near distance to provenance， high-energy environment and paleo-sag. Third， the oil-bearing property of source-reservoir alternating or integrated source-reservoir configurations is better than that of near-source thick reservoir type， with a pore throat of 15 nm and 70 nm as a boundary to determine whether the Lucaogou Formation contains oil and whether the reservoir has good oil-bearing property， respectively. Fourth， as guided by the correlation between pore throat structure and oil-bearing property， three types of oil layers （i.e.， Class Ⅰ， Class Ⅱ and Class Ⅲ） are identified. The second interval of the first member of Lucaogou Formation （Lu 1 Member） is characterized by well-developed reservoirs of high quality， good source-reservoir configuration， and large-scale distribution of sweet spots within. The research results are of a geological basis for the classification， evaluation and prediction of shale oil reservoirs in the Lucaogou Formation.

10.11743/ogg20220112