Abstract: After more than 60 years of exploration and development, Huanghua depression in Bohai Bay Basin has the accumulative proven oil geological reserves exceeding 13×10⁸t, where the proven conventional oil reservoirs exceed 50 %, facing great difficulty in increasing reserves on a large scale. Shale oil-gas and intra-source tight oil-gas resources have emerged as crucial exploration fields for future reserve growth and production increase in Dagang oilfield. Based on the drilling, geophysical, and analytical testing data obtained in recent years, a study has been conducted on the favorable conditions and enrichment characteristics for the formation of shale oil-gas and intra-source tight oil-gas resources in Huanghua depression, establishing theoretical insights into the intra-source hydrocarbon accumulation in faulted lake basin. The findings reveal that faulted lake basins possess geological conditions conducive to large-scale shale oil accumulation. Despite diverse lacustrine basin development environments, the organic matter abundance generally remains high in the study area. The lacustrine basin is characterized by small size with multiple sediment sources, and high brittle mineral contents; the high-frequency laminae develop, ensuring good source-reservoir matching at the microscopic scale. Additionally, the organic matter thermal evolution level is moderate, resulting in high retained oil content in shale. Shale oil in faulted lake basin possesses the enrichment characteristics of favorable fabric facies and hydrocarbon retention exceeding effect. The deep sag zones in faulted lake basin, located at the deposition/subsidence centers, have substantial accommodation space, and provide favorable conditions for intra-source tight oil enrichment, i.e., basin-mountain coupling, source-channel-sink matching, and two sand-rich accumulation modes developed in the deep sag zones. Effective reservoirs are developed under the control of both sedimentary facies and diagenetic facies. Moreover, source-reservoir coexistence and source-proximal charging result in the stable large-area distribution of reservoirs in the deep sag zones. Essentially, intra-source tight oil and shale oil in faulted lake basin correspond to source-reservoir combinations at different scales, exhibiting the orderly distribution of oil reservoirs and large-area continuous petroleum accumulation, which enable the integrated exploration and development. The theory of intra-source hydrocarbon accumulation in faulted lake basin has effectively guided exploration practices, providing an alternative field for the high-quality and sustainable development of mature oilfields.

Key words: Huanghua depression, faulted lake basin, intra-source hydrocarbon accumulation, shale oil-gas, tight oil-gas

摘要： 历经60余年的勘探开发,渤海湾盆地黄骅坳陷累计探明石油地质储量已超过13×10⁸t,其中,常规石油的探明程度超过50%,进一步规模增储的难度加大。页岩油气、源内致密油气已成为大港油田未来增储上产的重要勘探领域。基于近年来的钻井资料、地球物理资料以及分析测试数据等,对黄骅坳陷页岩油气、源内致密油气形成的有利条件和富集特征开展研究,形成了关于断陷湖盆源内油气成藏的理论认识。断陷湖盆具备页岩油大规模成藏的地质条件:尽管湖盆发育环境各异,但有机质丰度普遍较高;湖盆小且多物源输入,脆性矿物含量高;高频纹层发育,微观尺度下的源-储匹配关系好;有机质的热演化程度适中,页岩中的滞留油含量高。断陷湖盆的页岩油具备"优势组构相+滞留烃超越效应"的富集特征。断陷湖盆深凹区位于湖盆的沉积/沉降中心,可容空间大,具备源内致密油富集的有利条件:盆-山耦合,源-渠-汇匹配,深凹区发育2种富砂模式;受沉积相和成岩相共同控制,有效储层发育;源-储共生、近源充注,油藏呈大面积稳定分布。断陷湖盆的源内致密油和页岩油实质上对应了不同尺度下的源-储组合,油藏呈现出有序分布、大面积连续成藏的特征,具备一体化整体勘探开发的条件。断陷湖盆源内油气成藏理论认识有效指导了勘探实践,为老油田的高质量、持续发展提供了接替战场。

关键词: 黄骅坳陷, 断陷湖盆, 源内油气成藏, 页岩油气, 致密油气