渤海湾盆地东濮凹陷潜山油气成藏模式

Hydrocarbon accumulation models of buried hills in the Dongpu Sag， Bohai Bay Basin

李卓奕 谢敏

Zhuoyi LI Min XIE

针对渤海湾盆地东濮凹陷潜山供烃方式不明确以及油气成藏过程不清楚的问题，对东濮凹陷潜山的形态及内部结构进行了系统分类，并结合烃源岩发育特征及源-储对接关系，明确了不同类型潜山的供烃方式，厘清了断层、砂体及不整合输导体系对油气成藏过程的控制作用，提出了东濮凹陷潜山的油气富集成藏模式。研究结果表明：①东濮凹陷发育残丘山、断块山和滑脱山3种类型；具体可划分为单斜-残丘型潜山、褶皱-残丘型潜山、单斜-断块型潜山、褶皱-断块型潜山和单斜-滑脱型潜山5种潜山类型，其中主要为单斜-断块型潜山。②东濮凹陷潜山油气藏主要有两套烃源岩供烃，存在单向或双向供烃2个方向。油气主要通过阶梯状、桥式、侧接式、全接触式或切断式5种供烃方式向潜山储层充注，不同的供烃方式使潜山油气运移效率及成藏过程受到输导条件的控制。③断层的垂向输导能力、砂岩的侧向输导能力以及断层的侧向封闭性是断块潜山的油气差异运移聚集的主要控制因素；潜山不整合面的输导能力是不整合面附近油气成藏的关键控制因素，它决定了油气的聚集位置和成藏规模。东濮凹陷潜山供烃方式及输导条件的差异是导致潜山油藏成藏差异的主要原因。其中，全接触式和桥式双向供烃的挤压-拉张型内部褶皱-断块型潜山油气最为富集，而单向阶梯式供烃的侵蚀型单斜-残丘型潜山的油气富集程度相对较低。

The hydrocarbon supply modes and accumulation processes of buried hills are yet to be clarified in the Dongpu Sag， Bohai Bay Basin. In this regard， we systematically classify the buried hills based on their morphologies and internal structures. In combination with the developmental characteristics of source rocks and the source rock-reservoir contact relationships， we determine the hydrocarbon supply modes of various buried hills， as well as the controlling effects of the fault-sand body-unconformity carrier system on the hydrocarbon accumulation process. Accordingly， the hydrocarbon enrichment and accumulation patterns of buried hills in the Dongpu Sag are proposed. The results indicate that the Dongpu Sag exhibits three buried-hill morphologies： residual， fault-block， and decollement. These hills can be categorized into five types based on their internal structures， namely monoclinal-residual， folded-residual， monoclinal-fault-block， folded fault-block， and monoclinal-decollement buried hills， with the monoclinal-fault-block type predominating. Hydrocarbon reservoirs therein are primarily supplied by two suites of source rocks， unidirectionally or bidirectionally. Hydrocarbon charging occurs principally through five supply modes： stepped， bridging， lateral-contact， full-contact， and cutting-through. Therefore， the hydrocarbon migration efficiency and accumulation processes in these buried hills are under the action of diverse hydrocarbon transport conditions. The differential hydrocarbon migration and accumulation in fault-block buried hills are primarily governed by the vertical transport capacity of faults， lateral transport capacity of sandstones， and the lateral sealing performance of faults. In addition， for hydrocarbon accumulation near the unconformities in the buried hills， the transport capacity of the unconformities represents a key controlling factor， determining the locations of hydrocarbon enrichment and the scales of hydrocarbon reservoirs. The differential hydrocarbon accumulation in the buried hills is attributed primarily to the differences in hydrocarbon supply modes and transport conditions. Specifically， the compressional-tensile folded-block-block buried hills， receiving bidirectional hydrocarbon supply through full contact and bridging， exhibit the most significant hydrocarbon enrichment. In contrast， the erosional monoclinal-residual buried hills with unidirectional， stepped hydrocarbon supply display a relatively low degree of hydrocarbon enrichment.

10.11743/ogg20250206