准噶尔盆地腹部复合圈闭成藏特征研究

HYDROCARBON ACCUMULATION CHARACTERISTICS OF COMBINATION TRAPS IN THE ABDOMEN OF JUNGGAR BASIN

准噶尔盆地是一个勘探程度相对较高的盆地,可供勘探的构造圈闭已经越来越少,因此地层岩性圈闭甚至构造岩性复合圈闭就成了油气勘探的主要目标了。对于准噶尔盆地腹部情况更是这样,由于准噶尔盆地腹部构造活动不强烈,构造圈闭相对较少,寻找岩性或构造岩性复合圈闭就显得更加迫切了。根据地震地层学、层序地层学和沉积相分析研究,准噶尔盆地腹部地区主要目的层侏罗系三工河组和八道湾组主要为河流相-三角洲相-半深湖相沉积,储集地层以各类河道砂体、三角洲前缘砂体为主。根据构造演化研究,准噶尔盆地腹部上构造层(侏罗系及上覆地层)主要为向北抬升的单斜层,这样的构造背景正好与各类岩性砂体复合形成复合圈闭。由于侏罗系和白垩系砂体展布复杂,导致工区油水关系复杂,从而使得工区复合成藏非常复杂。

Junggar Basin is a highly explored basin, with few unexplored structural traps remaining. Thus the lithologic trap, and even the structural lithologic trap, have become the main target of oil-gas exploration. This is especially evident in the abdomen of Junggar Basin, where the weak structural movement resulted in less structural trap, making it more urgent to look for lithologic or structural lithologic combined traps. According to the sedimentary facies analysis with seismic stratigraphy and sequence stratigraphy, in the abdomen of Junggar Basin, the Jurassic Sangonghe formation and Bandaowan formation in the main target strata are mainly flurial-delta-semi-deep lake facies. And the reservoirs are mainly composed of various kinds of channel sand and deltaic front sand. In accordance with the research on structural evolution, the suprastructure (Jurassic and overlying formation) in the abdomen of Junggar Basin is mainly monoclinal formation uplift to the north. This structural background, combined with various kinds of lithologic sand, forms combination trap. The complicated distribution of Jurassic and Cretaceous sand results in the complex relationship between oil and water in the study area, thereby makes the combination on accumulation quite complicated.