潜江凹陷潜江组盐间页岩含油性及其勘探意义

Oil-bearing characteristics and exploration significance of inter-salt shale in Qianjiang formation, Qianjiang depression, Jianghan basin

为研究江汉盆地潜江凹陷不同构造部位盐间页岩的含油性和勘探潜力,以王场构造带W99井潜34段10韵律钻井岩心为主要研究对象,结合相邻井的岩心分析资料,通过岩石常规热解和多温阶热解实验方法分析了构造凸起区和深凹区盐间页岩含油性特征,认为凸起区页岩含油性好的原因是来自深凹区页岩运移油贡献.研究结果表明:35件凸起区页岩样品总有机碳丰度TOC值在0.60%~6.38%之间,平均值为3.39%,岩石热解S1值在2.73~28.47 mg/g之间,平均值为14.14 mg/g,含油饱和度指数OSI值普遍大于100 mg/g,在225~564 mg/g之间,平均值达405 mg/g,现实可动油量S1-1值在0.75~5.89 mg/g之间,平均值为3.26 mg/g,这些指标均达到了优质烃源岩的标准,但凸起区页岩的成熟度较低,含油性好的主要原因是深凹区的成熟-高熟油通过侧向运移,在凸起部位聚集.深凹区存在比较丰富的原位页岩油富集,下一步勘探部署需加以重视.

In order to study the oil content and exploration potential of inter-salt shale in different structural positions in Qianjiang depression, Jianghan basin, the cores from the 10 th rhythmic of the Eq3 member of Qianjiang formation of well W99 and adjacent wells were taken as the main research objects. The oil-bearing characteristics of inter-salt shale from the uplift area and depression area were analyzed by the Rock-Eval 6 with both conventional pyrolysis heating program and the multi-stage temperature pyrolysis analysis heating program. The results show that the inter-salt shale from the uplift area has excellent oil content due to the contribution of migrated shale oil from the depression area. The total organic carbon(TOC) values of 35 samples from the uplift area are between 0.60% and 6.38%, with an average of 3.39%. The S1 values of rock pyrolysis are between 2.73 and 28.47 mg/g, with an average of 14.14 mg/g. The oil saturation index(OSI) values are between 225 and 564 mg/g and generally greater than 100 mg/g, with an average of 405 mg/g. And the realistic movable oil S1-1 values are between 0.75 and 5.89 mg/g, with an average of 3.26 mg/g. Although these indexes meet the high-quality source rock standard, the maturity of shale in the uplift area is low. The main reason for good oil content is the lateral migration of mature to high mature shale oil from the depression area. Therefore, it is considered that there should be in-situ shale oil enrichment in the depression area, and more attention should be paid to the future exploration and deployment.