深层古近系“汇聚脊”对浅层新近系油气聚集的控制作用——以渤海湾盆地环渤中地区为例

Control of deep Paleogene“catchment ridge”on shallow Neogene hydrocarbon accumulation:A case study around Bozhong area in Bohai Bay Basin

根据渤海海域多年的勘探实践经验,“汇聚脊”可以划分为凸起型、凹中隆起型、陡坡带砂体型3种类型。目前对于“汇聚脊”的控藏机理和控油气运聚过程尚不清晰。为解决渤海海域浅层不同构造带油气成藏差异显著的问题,利用油气运移物理模拟实验对“汇聚脊”的控藏机理和控油气运聚过程进行分析。结果表明:凸起型“汇聚脊”规模大、幅度高,汇烃能力最强,在断层沟通下,其上的浅层新近系油气藏规模最大;凹中隆起型“汇聚脊”的面积和幅度中等,浅层油气成藏规模以中型为主;陡坡带砂体型“汇聚脊”依靠砂体的汇聚作用,也具有较强的汇烃能力,浅层新近系也可以形成大中型油气藏;深层发育“汇聚脊”是浅层油气富集的必要条件。“汇聚脊”控藏理论的提出可以有效指导渤海油田的浅层油气勘探实践,同时对相似背景下陆地油田的油气勘探也同样具有借鉴意义。

Based on years of exploration experience in Bohai Sea area,“catchment ridge”can be divided into 3 types including uplift,middle-sag uplift and steep-slope sandbody.Currently,mechanism of“catchment ridge”controlling reservoirs and controlling process of hydrocarbon migration and accumulation are still unclarified.In or-der to solve the problem of significant hydrocarbon accumulation difference in different structural belts of shallow Bohai Sea area,physical simulation experiment of hydrocarbon migration are performed to analyze mechanism of“catchment ridge”controlling reservoirs and controlling process of hydrocarbon migration and accumulation.The re-sults show that uplift-type“catchment ridge”is characterized by large scale and high amplitude,with the maximum hydrocarbon catchment capability.Connected by faults,shallow Neogene reservoirs above it have the largest scale.Middle-sag uplift type“catchment ridge”has moderate area and amplitude,and shallow reservoirs have mainly me-dium accumulation scale.Relying on sandbodies catchment,steep-slope sandbody type“catchment ridge”also has high hydrocarbon catchment capability,and can form medium-large shallow Neogene reservoirs.Deep developed“catchment ridge”is a necessary condition for shallow oil and gas enrichment.The proposal of“catchment ridge”controlling reservoirs theory effectively guides shallow oil and gas exploration in Bohai Oilfield,and also provides reference significance for oil and gas exploration in onshore oilfields in similar background.