苏北盆地古近系阜宁组二段页岩油储集空间特征及甜点段评价——以溱潼凹陷QY1井为例

Characteristics of reservoir space and sweet spot evaluation of shale oil in the second member of Paleogene Funing Formation in Subei Basin: a case study of well QY1 in Qintong Sag

高玉巧 蔡潇 夏威 吴艳艳 陈云燕

GAO Yuqiao CAI Xiao XIA Wei WU Yanyan CHEN Yunyan

1. 中国石化 华东油气分公司 勘探开发研究院, 南京 210000; 2. 中国石化 深层煤层气勘探开发重点实验室, 南京 210000

1. Exploration and Development Research Institute, SINOPEC East China Oil and Gas Company, Nanjing, Jiangsu 210000, China; 2. SINOPEC Key Laboratory of Deep Coalbed Methane Exploration and Development, Nanjing, Jiangsu 210000, China

苏北盆地古近系阜宁组二段是常规油重点产层，同时也是中国东部陆相页岩油勘探开发的优选层位。对溱潼凹陷QY1井岩心样品进行分析测试表明，该套页岩具有低有机质丰度、较低镜质体反射率(Ro)、矿物组分均衡及孔隙网络复杂的特点；运用岩石学及地球化学方法等对该页岩油储层的岩相特征、储集空间特征、含油性与可动性、脆性指数与可压性特征等进行研究，指明了生产甜点段。阜二段是一套混积页岩纹层型储层，矿物组成以黏土、长英质和碳酸盐矿物为主，有机碳含量平均值为1.32%，Ro为0.9%～1.1%；平均孔隙度中下部为4%，上部为2.2%。根据“有机质丰度+构造特征+岩性”将阜二段页岩划分为6种岩相，其储集性具有明显差异，纹层发育特征的差异是导致不同岩相具有不同储集空间特征的重要原因。除低有机质纹层/层状灰云质页岩外，其他岩相都具有较好的含油性；高有机质层状灰质页岩的有机碳含量最高。纹层数量与油气可动性具有较好的对应性，从中有机质纹层状含灰云页岩到高有机质块状泥岩，平均含油饱和度指数从202.62 mg/g降至77.83 mg/g。高有机质块状泥岩由于存在大量塑性矿物，造缝效果是6种岩相中最差的。中有机质纹层状含灰云页岩是最优岩相，中有机质层状含灰云页岩和中有机质纹层/层状灰云质页岩略差，但也可以作为优势岩相成为勘探开发的重点。根据优势岩相在纵向上的分布，优选阜二段Ⅰ亚段③—⑤小层和Ⅱ亚段②—④小层为该区地质甜点段。

The second member of the Paleogene Funing Formation in the Subei Basin is a key production layer for conventional oil and an optimal target for the exploration and development of continental shale oil in East China. The analysis and testing of core samples from well QY1 in the Qintong Sag indicate that the shale features low total organic carbon (TOC) content, relatively low vitrinite reflectance (Ro), balanced mineral composition, and a complex pore network. Using petrological and geochemical methods, the lithofacies characteristics, reservoir space characteristics, oil-bearing and mobility characteristics, brittleness index, and compressibility characteristics of this shale oil reservoir were studied to identify production sweet spots. The second member of the Funing Formation is a mixed shale layered reservoir, with mineral composition mainly consisting of clay minerals, felsic minerals, and carbonate minerals. The average TOC value is 1.32%, and Ro ranges from 0.9% to 1.1%. The average porosity is 4% in the middle and lower parts and 2.2% in the upper part. Based on the abundance of organic matter, structural characteristics, and lithology, the shale of the second member of the Funing Formation can be divided into six lithofacies, with significant differences in reservoir properties. The development characteristics of the laminae are an important reason for the different reservoir space characteristics among different lithofacies. Except for low organic matter laminated/layered shale with poor calcite and dolomite, other lithofacies have good oil content. The high organic matter layered shale with rich calcite demonstrates the highest TOC content. The number of layers correlates well with oil and gas mobility, with the average OSI value decreasing from 202.62 mg/g in medium organic matter laminae shale with poor calcite and dolomite to 77.83 mg/g in high organic matter massive mudstone. High organic matter massive mudstone, due to the presence of a large amount of plastic minerals, has the worst fracturing effect among the six types of lithofacies. Medium organic matter laminae shale with poor calcite and dolomite is the optimal lithofacies, while medium organic matter layered shale with poor calcite and dolomite and medium organic matter layered shale with rich calcite and dolomite are slightly less favorable but can still be key targets for exploration and development. Based on the vertical distribution of the dominant lithofacies, sublayers ③ to ⑤ of submember Ⅰ and sublayers ② to ④ of submember Ⅱ of the second member of the Funing Formation are selected as geological sweet spots in this area.

中国石化科技部项目(P21112，P23190)资助。

https://doi.org/10.11781/sysydz202405916