渤海海域油气运移“汇聚脊”模式及其对新近系油气成藏的控制

渤海海域新近系是重要的勘探层系,但不同构造区带的新近系油气成藏差异很大。通过渤海海域新近系不同构造带油气分布特征和富集规律的研究,提出在古近系中发育"汇聚脊"是造成上覆新近系有利圈闭成藏的关键。"汇聚脊"是有利于油气聚集的低势区,包括高凸起型、陡坡沉积砂体型和凹中古地貌隆起型3种类型。新近纪晚期,在凹陷内的掀斜断块构造和缓坡区的断块构造中,由于古近系不发育"汇聚脊",新近系难以形成商业性油气藏。依据新近系的有利构造圈闭与"汇聚脊"的空间和时间关系建立了油气成藏模式。油气运移的"汇聚脊"及其控藏模式的建立是对渤海湾盆地浅层油气成藏理论的丰富,可指导渤海海域新近系较高成熟勘探域的勘探。

The “catchment ridge” model of hydrocarbon migration in Bohai Sea and its control on Neogene hydrocarbon accumulation

The Neogene System in Bohai Sea area is an important exploration stratum, and the Neogene hydrocarbon accumulation in various tectonic zones shows a significant difference. Through studying the hydrocarbon distribution characteristics and enrichment laws of different Neogene structural belts in Bohai Sea, it is proposed that the "catchment ridge" developed in Paleogene is the key to form the overlying Neogene favorable trap accumulation. The "catchment ridge" is a low potential area conducive to oil and gas accumulation, including three types of high uplift, steep-slope sedimentary sand and concave paleo-geomorphologic uplift. In the late Neogene period, it was difficult for the Neogene system to form commercial oil and gas reservoirs due to the lack of Paleogene "catchment ridge" in hatchback fault block structure in the depression and fault block structure in the gentle slope area. The hydrocarbon accumulation model was established based on the spatial and temporal relationship between the favorable structural traps and the "catchment ridge" of the Neogene System. The "catchment ridge" for hydrocarbon migration and the establishment of reservoir control model have enriched the shallow hydrocarbon accumulation theory in Bohai Bay Basin, which can guide the exploration in Neogene highly mature exploration domain of Bohai Sea, and also has a great significance to explore the large and medium-sized oilfields detected in the recent period.