苏北盆地高邮凹陷古近系阜宁组二段页岩油富集主控因素

Main controlling factors of shale oil enrichment in second member of Paleogene Funing Formation in Gaoyou Sag of Subei Basin

段宏亮 孙雅雄 杨保良

DUAN Hongliang SUN Yaxiong YANG Baoliang

中国石化 江苏油田分公司 勘探开发研究院, 江苏 扬州 225009

Research Institute of Exploration and Development, SINOPEC Jiangsu Oilfield, Yangzhou, Jiangsu 225009, China

高邮凹陷古近系阜宁组二段是苏北盆地页岩油勘探的重点区带和层系，已部署实施的8口页岩油水平井的成功，证实其具有非常大的页岩油勘探潜力和良好的勘探前景。针对该层段页岩油井产能存在差异、富集主控因素认识不清楚等难点问题，综合利用岩心、测录井、分析测试数据和生产动态数据等资料，对阜二段地质特征和页岩油富集主控因素进行研究。高邮凹陷阜二段泥页岩以长英质—黏土质混积岩和长英质—灰质/白云质混积岩为主，有机质丰度中等，有机质类型以Ⅰ型和Ⅱ1型为主；自下向上有机质类型由腐殖型向腐泥型逐渐转变，有机质丰度总体由低逐渐增高，具有较好的页岩油形成条件。综合岩相、生油性、含油性、储集性、可压性等多因素评价可知，高邮凹陷阜二段共发育Ⅴ-4～Ⅴ-9、Ⅳ-2～Ⅳ-7小层和Ⅱ～Ⅲ亚段三套勘探有利层段。阜二段页岩油富集具体表现为：①有利岩相组合是页岩油富集的物质基础，其中混积岩夹白云石条带是有利的源—储配置组合，页岩油产能高；②复杂的孔缝系统是页岩油富集的核心，层理缝和裂缝是页岩油流动的主要通道，有效沟通基质孔隙，提高页岩油导流能力；③较高的成熟度和良好的保存条件是页岩油高产稳产的关键，镜质体反射率(Ro)介于0.8%～0.9%时滞留油含量相对较高，远离长期活动性断层的井游离烃含量(S1)相对较高。

The second member of the Paleogene Funing Formation in the Gaoyou Sag is a key area for shale oil exploration within the Subei Basin. The successful implementation of eight horizontal shale oil wells evidences its significant potential and promising prospects of exploration. Addressing challenges such as variations in well productivity and unclear understanding of the main controlling factors of shale oil enrichment, this study utilized core data, logging data, analysis testing data, and production dynamics to investigate the geological characteristics and main controlling factors of shale oil enrichment in the second member of the Funing Formation. The results reveal that the mudstone and shale in this member predominantly consist of felsic-argillaceous mixed rocks and felsic-calcilutite/dolomitic mixed rocks, with moderate organic matter abundance and mainly TypeⅠand TypeⅡ1 organic matter. From bottom to top, the organic matter type gradually transitions from humus to sapropelic, with an overall increase in organic matter abundance, providing favorable conditions for shale oil formation. A comprehensive evaluation of lithofacies, oil generation potential, oil content, reservoir characteristics, and compressibility identified three favorable exploration layers in the second member of the Funing Formation: Ⅴ-4 to Ⅴ-9, Ⅳ-2 to Ⅳ-7, and Ⅱ to Ⅲ.Shale oil enrichment in the second member of the Funing Formation is characterized by the following factors: (1) Favorable lithofacies combinations, particularly mixed rocks interbedded with dolomite bands, form the material basis for shale oil enrichment, resulting in high shale oil productivity. (2) A complex pore and fracture system is central to shale oil enrichment, with laminar fractures and cracksserving as the main pathways for shale oil flow, effectively connecting matrix pores and enhancing shale oil conductivity. (3) Higher maturity and favorable preservation conditions are crucial for high and stable shale oil production, with vitrinite reflectance (Ro) between 0.8% and 0.9%, indicating relatively higher retained oil content. Wells located away from long-term active faults exhibit relatively higher free hydrocarbon (S1) content.

国家自然科学基金面上项目(42072155)、中国石化科技部项目(P21113、P23189)、中国石化江苏油田分公司科研课题(JD22002)和江苏省卓越博士后计划共同资助。

https://doi.org/10.11781/sysydz202403441