低凸起带油气充注机理及运聚模式:以济阳坳陷林樊家低凸起带为例

Hydrocarbon Filling Mechanism and Accumulation Model in Low-uplift Zone:Taking Linfanjia Low-uplift Zone of Jiyang Depression as an Example

断陷盆地低凸起带具有远离油源,油气富集层系浅的特点,其油气充注机理及运聚模式研究还较薄弱。以济阳坳陷林樊家低凸起带为例,从油气来源入手,分析了油气成藏动力与阻力的关系,探讨了低凸起带油气充注方式和运聚模式。结果表明:林樊家低凸起带原油具有高伽马蜡烷/C30霍烷值、低姥植比的特点,来源于利津洼陷沙四上亚段烃源;在成藏地质背景分析的基础上,结合成藏动力-阻力计算结果,确定了林樊家低凸起带油气主要为"断层双重输导-多层系充注-不整合面分流"的充注方式;根据断层在活动时期和静止时期输导方式及输导能力的差异,结合圈闭发育情况,林樊家低凸起带油气成藏可总结为"断层垂向输导-岩性尖灭控圈"、"断层侧向输导-‘天窗’开启-岩性尖灭控圈"、"断层侧向输导-不整合面遮挡"、"断层侧向输导-岩性尖灭控圈"等4种成藏模式。

The low uplift zone in faulted basin is far away from oil source, and the oil-bearing layers are quite shallow. The study on hydrocarbon filling mechanism and migration-accumulation model in faulted basin is very weak. Taking Linfanjia low-uplift zone in Jiyang depression as an example, the relationships between reservoir-forming dynamic and resistance were analyzed, and the hydrocarbon filling feature and migration-accumulaiton model of low-uplift zone were discussed. The results show that the crude oil in Linfanjia low-uplift zone has the characteristics of high gammacerane/C3o hopane and low ratio of pristane to phytane （Pr/Ph）, which is quite similar to that of source rocks of the upper sub-member of the fourth member of Shahejie Formation in Lijin depression. What is more, according to the analysis of the geological setting of reservoir, based on the results calculated by reservoir-forming dynamic and resistance, the hydrocarbon filling model in Linfanjia low-uplift zone is ＂fault double transport-multi-layer filling-unconformity filter＂. In addition, considering the differences of transporting mode and capacity between activity and stationary periods, combined with hydrocarbon occurrence and trap development, the accumulationmodes in Linfanjia low-uplift zone can be summarized as ＂fault vertical transport-lithology controlled trap＂, ＂fault lateral transport-＇ clearstory ＇ open-lithology controlled trap＂, ＂fault lateral transport- uncomformity screen＂ and ＂fault lateral transport-lithology controlled trap＂.