冀中坳陷潜山油气藏特征

Characteristics of buried hill reservoir in Jizhong Depression

由于碳酸盐岩储集体非均质性极强,造成油气分布十分复杂,使得冀中坳陷潜山油气勘探难度加大。该文利用石油地质、地球物理、有机地球化学等理论和方法,结合勘探实践,对冀中坳陷潜山油气藏特征进行了系统的研究。结果表明:潜山油气主要来源于古近系和石炭系—二叠系烃源岩;储集层主要由中上元古界和下古生界碳酸盐岩组成,储集空间主要为孔、洞、缝系统;古近系泥质岩、石炭系—二叠系煤系地层和潜山内幕泥质岩隔层构成了潜山油气藏良好的盖(隔)层,并发育2类、8套储盖组合;潜山发育的断层和不整合是油气的主要运移通道。根据圈闭类型的差异,将潜山油气藏分为潜山顶油气藏、潜山坡油气藏和潜山内幕油气藏3种类型。潜山油气近油源分布,具东富西贫、南油北气的特征,并在断裂带附近的潜山及潜山内幕圈闭中富集,构成了复式油气聚集带。研究成果有助于深入揭示冀中坳陷潜山油气成藏规律,对今后潜山圈闭评价、区带优选等也具有很好的指导作用。

It is difficult to explore the buried hill reservoir in Jizhong Depression because of the strong heterogeneity of carbonate reservoirs and the complex hydrocarbon distribution. The theories and methods of petroleum geology, geophysics and organic geochemistry, combined with exploration practice, were applied to systematically study the charac-teristics of buried hill reservoir in Jizhong Depression. The result shows that the hydrocarbon in buried hill mainly came from the source rocks of Eogene and Permo-Carboniferous system. The reservoir is composed of Middle-Upper Praterozoic and Lower Paleozoic carbonate rocks, and pores, caves and fractures are the main reservoir spaces. The cap rocks are composed of argillaceous rocks of Eogene, coal measure strata of Permo-Carboniferous system and interlayers of inner buried hills, and there developed eight sets of reservoir-cap rocks assemblage. The faults and unconformities are the main hydrocarbon migration pathways of buried hills. The buried hill reservoirs can be divided into hilltop type, hillside type and inner buried hill type. The buried hill reservoirs are mainly located in eastern depressed areas, and distributed close to fractural belts near source rocks, forming the complex hydrocarbon accumulation belts. These research results will be helpful for the disclosure of hydrocarbon accumulation rules, and provide guidance for the target evaluation and favorable zone selection.