江汉盆地潜江凹陷潜江组盐间页岩油储层矿物组成与脆性特征研究

Mineral composition and brittleness characteristics of the inter-salt shale oil reservoirs in the Qianjiang Formation, Qianjiang Sag

王芙蓉 何生 郑有恒 侯宇光 吴世强

Wang Furong He Sheng Zheng Youheng Hou Yuguang Wu Shiqiang

中国地质大学构造与油气资源教育部重点实验室, 武汉 430074 2. 中国石化江汉油田分公司勘探开发研究院, 武汉 430223

Key Laboratory of Tectonics and Petroleum Resources of Ministry of Education, China University of Geoscience, Wuhan, Hubei 430074, China 2. Research Institute of Exploration and Development, SINOPEC Jianghan Oilfield Branch Company, Wuhan, Hubei 430223, China

应用X射线衍射分析技术对潜江组潜二-四段的页岩岩心样品进行了矿物组成与脆性特征研究,以及有机地球化学实验,结果表明,各样品具有差异的矿物组成和地球化学特征。潜二段页岩有机质以腐泥型为主,TOC平均值为1.38%,总体处于未熟-低熟阶段(Ro为0.26%~0.5%),矿物中蒸发岩类矿物含量高;潜三段页岩有机质以腐泥型和腐殖腐泥型为主,TOC平均值为2.53%,总体处于低熟-中等成熟阶段(Ro为0.5%~0.88%),矿物中石英和黏土含量较高;潜四段页岩有机质以腐泥型和腐殖腐泥型为主,TOC平均值为0.69%,总体处于中等成熟-成熟范围(Ro为0.55%~1.3%),碳酸盐矿物含量较高。与北美及中国其他地区的页岩相比,潜江组盐间页岩具有"低黏土矿物、低石英、高碳酸盐、低脆性矿物"的特征,但其中潜三段的脆性矿物含量较高(平均56%),脆性指数较大(平均75.3%),具有较好的脆性,是潜江组盐间页岩最有利的勘探层段。

Core samples of shales from the second (Eq2), third (Eq3) and fourth (Eq4) members of the Qianjiang Formation in the Qianjiang Sag were analyzed using X-ray diffraction (XRD) analyses to determin their mineral composition, brittleness and geochemical characteristics. The results showed that the shales from different formations have different mineral compositions and geochemical characteristics. The shales in Eq2 have sapropelic organic matter. The TOC content averages 1.38%. The Ro value ranges from 0.26%-0.5%, indicating an immature to low-maturity thermal evolution stage. Evaporite rocks are in high content. The shales in Eq3 have sapropelic and humic-sapropelic organic matter. The TOC content averages 2.53%. The Ro value ranges 0.5%-0.88%, indicating a low to medium-maturity thermal evolution stage. Quartz and clay minerals are in high content. The shales in Eq4 have sapropelic and humic-sapropelic organic matter. The TOC content averages 0.69%. The Ro value ranges 0.55%-1.3%, indicating a medium-maturity to mature thermal evolution stage. Carbonate minerals are in high content. The inter-salt shales in the Qianjiang Formation are characterized by "low clay content, low quartz content, high carbonate content, and low brittle mineral content" compared to those in the USA and other regions in China. The shales in Eq3 have higher brittle mineral content (average 56%) and higher brittleness index (average 75.3%), which show excellent exploration potential.

国家自然科学基金青年基金项目(41302111)资助。

https://doi.org/10.11781/sysydz201602211