渤海海域渤东低凸起差异演化及控藏作用

    Differential evolution of Bodong low uplift in Bohai Sea area and its control over oil and gas accumulation

    • 摘要: 以渤东低凸起及其围区钻井和三维地震等资料为基础,基于断层活动性统计、断裂体系展布特点和构造样式分析以及构造恢复等方法,恢复了渤东低凸起南北凸起的演化与形成机制。结果表明,该地区发育3期断裂体系,分别为古新世—始新世断裂系统、渐新世断裂系统以及新近系断裂系统;渤东低凸起北高南低,北凸起自古近纪裂陷早幕开始形成,在东营组沉积时期继续隆升,形成单断式掀斜垒块;而南凸起在裂陷早幕开始活动,抬升幅度相对较低,东营组沉积时期受郯庐断裂剧烈走滑的影响,断裂活动强烈,发育二台阶,形成双断式地垒;北凸起边界断层持续活动,裂陷早幕和晚幕构造叠合较好,油气顺断层运移到浅层成藏;南凸起双断式地垒构造,二台阶断层不直接沟通油源,在深层形成地层超复型油藏。南北凸起不同的成藏模式对于下一步的油气勘探具有一定的指导意义。

       

      Abstract: Based on the drilling and 3D seismic data collected from the Bodong low uplift and its surrounding areas, we studied in this paper the forming process of Bodong low uplift by means of fault systems, structural styles, fault activities and balanced profiles, and its control over hydrocarbon accumulation was also discussed. Three fault systems are found well developed in the area, namely, the Paleocene-Eocene fault system, the Oligocene fault system and the Neogene fault system. The Bodong low uplift is high in the north and low in the south in an overview. The north high started rising up in early Paleogene and continued through the whole period of Dongying Formation, and as the result a single fault tilting barrier was formed. The south uplift was activated in the early stage of the rifting, and the uplifting range was relatively small. During the depositional period of the Dongying Formation, the Tanlu fault suffered a strong strike-slip move, which caused the formation of a double-fault horst. The boundary faults of the north uplift kept active, and the early and late episodes of the rift well overlapped. Oil and gas may migrate along faults to shallower reservoirs. In the double-fault horst of the south uplift, the two-step faults do not connect directly to the oil source, and thus an overlapping stratigraphic reservoir formed in the deep layer. It is believed that different reservoir-forming models on the north and south uplifts have certain guiding significance for future oil and gas exploration.

       

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