渤中凹陷西斜坡新近系油气成藏主控因素及有利勘探方向

Main Controlling Factors of Hydrocarbon Accumulation and Prediction of Favorable Exploration Zone of Neogene in the Western Slope of Bozhong Sag

近年来,渤中凹陷西斜坡新近系油气勘探相继取得重大突破,成为深入挖潜的重要区带。在对渤中凹陷西斜坡新近系油气分布和油源分析的基础上,总结了该斜坡新近系油气成藏的主控因素。结果表明:源岩发育特征、断裂展布特征以及圈闭类型主控了油气分布;研究区西部多洼共生,沙河街组烃源岩发育,并且被长期活动性油源断裂深切洼陷,为新近系浅层油气成藏提供了优越条件;研究区南部由于缺乏深切沙河街组烃源岩的大断裂,难以将油气运移至浅层,不利于油气聚集成藏。因此,渤中凹陷西斜坡应该遵循"环洼选区、主断控带"的勘探理念,重视次洼周边的勘探,以寻找生烃次洼周边有效的运移断层为工作重点,研究区西北部为新近系油气勘探的有利区带。

A series of breakthroughs has been made in petroleum exploration of Neogene in the western slope of Bozhong sag in recent years,which makes this area become favorable.On the basis of distribution and hydrocarbon source of Neogene in the western slope,the main controlling factors of hydrocarbon accumulation were summarized,and the favorable exploration zone was proposed.Researches on hydrocarbon source and distribution of Neogene of the western slope indicate that the oil and gas distribution is controlled by source rock development characteristics,fracture characteristics and trap types;in the west area,symbiotic sag,hydrocarbon source rocks and long-term activities of oil source faults are well developed,which provides a favorable condition for the formation of oil and gas reservoir in shallow strata;due to the lack of deep Shahejie Formation source rocks of fault,it is difficult for oil and gas migration to shallow,and is not conducive for the accumulation of oil and gas;these regions,which are close to subsag and fault belts,should be the preferable prospects in the exploration process of Neogene in the western slope of Bozhong sag,and more attention should be paid on faults which could be migration pathway and regions near subsag.Southwest part of the study area is the most favorable zone.