苏北盆地陆相“断块型”页岩油地质特征及勘探实践

Geological characteristics and exploration of continental fault-block shale oil reservoirs in the Subei Basin

方志雄 肖秋生 张殿伟 段宏亮

Zhixiong FANG Qiusheng XIAO Dianwei ZHANG Hongliang DUAN

中国东部陆相断陷盆地群中-新生代发育多套巨厚的湖相富有机质页岩，蕴含丰厚的页岩油资源，但富有机质页岩普遍受断层切割，形成若干独立断块，与北美连续稳定分布的页岩地层条件存在较大差异，能否获得稳定的商业油流是勘探面临的首要问题。基于苏北盆地高邮凹陷古近系阜（阜宁组）二段页岩岩性、烃源岩品质、储层品质研究与综合评价，研究认为阜二段发育3套厚层有利层，具备“多层楼”立体勘探开发条件；基于阜二段有利层、断层和断块发育地质现状，提出水平井在同一断块内或跨断块、在同一或多个有利层长距离穿行的“断块型”页岩油勘探思路；根据断层断距与有利层厚度之间的配置关系，将“断块型”页岩油划分为“连续稳定”型、“微断层切割”型和“跨断块多甜点”型等3种勘探目标类型。通过勘探实践，证实3种勘探目标类型均可获得稳定的商业油流。研究成果丰富了中国陆相页岩油勘探领域和类型，对陆相断陷盆地页岩油勘探具有重要借鉴意义。

Continental faulted basins in eastern China contain multiple suites of significantly thick lacustrine organic-rich shales of the Mesozoic and Cenozoic， thus boasting abundant shale oil resources. However， these organic-rich shales are extensively dissected by faults， resulting in multiple isolated fault blocks. This is a big difference compared with the shale strata in North America in continuous and stable distribution， and poses the challenge to obtain stable commercial oil flow in exploration. Based on the investigation and comprehensive assessment of the lithology， and quality of source rocks and reservoir of shales in the 2 member of the Funing Formation （also referred to as the Fu 2 Member） in the Gaoyou Sag， Subei Basin， we hold that three suites of thick target intervals are developed in the Fu 2 Member， which can be explored and exploited as a whole. Given the current geological conditions of the target intervals， faults， and fault blocks in the Fu 2 Member， we propose an idea for fault-block shale oil reservoir exploration， that is， to have long laterals landed within a single or across multiple target intervals within a single or multiple fault blocks. Considering the correlation between fault throw and target interval thickness， we divided the fault-block shale oil reservoirs into three types for exploration， that is， the continuous and stable reservoir， reservoir dissected by micro-faults， and the reservoir spanning multiple fault blocks with multiple sweet spots. It has been verified through practical exploration that all these exploration targets can yield stable commercial oil flow. The study results have expanded the exploration targets and reservoir types for continental shale oil in China， thus serving as a significant reference for shale oil exploration in continental faulted basins.

10.11743/ogg20230611