车排子凸起沙湾组油气成藏条件研究

Study on hydrocarbon accumulation conditions of Shawan Formationin Chepaizi Uplift

准噶尔盆地车排子凸起新近系沙湾组油藏主要以岩性油藏为主,原油性质多样,有轻质油、中质油和稠油。通过对油源、古地貌、输导体系及沉积特征研究,轻质油主要来自侏罗系烃源岩,稠油来自二叠系烃源岩,中质油为混源所致;古地貌影响着油气运移方向;烃源岩供烃影响着成藏时间;厚砂及多期不整合面、断裂系统构成了输导体系;曲流河侧积砂坝是形成岩性油藏的关键因素。不同凹陷供烃的成藏模式不同:昌吉凹陷二叠系烃源岩生成的原油先形成白垩系油藏,后期在断层调整下进入沙湾组成藏,侏罗系烃源岩通过断裂体系和厚砂体运移至沙二段成藏;四棵树凹陷侏罗系烃源岩的油气输导至西南沙一段成藏。

The Neogene Shawan Formation reservoirs of Chepaizi Uplift in Junggar Basin are mainly lithologic reservoirs with various crude oil properties,including light oil,medium oil,and heavy oil.According to the study of oil source,paleogeomorphology,transport system,and sedimentary characteristics,light oil mainly comes from Jurassic source rocks,heavy oil comes from Permian source rocks,and medium oil is caused by mixed sources;Palaeogeomorphology influences the direction of oil and gas migration;hydrocarbon supply from source rocks affects the time of reservoir formation;thick sand,multi-phase unconformity and fault systems constitute the transportation system;alluvial bars on the side of the meandering river are the key factors in forming a lithologic reservoir.The hydrocarbon accumulation patterns in different sags are different:the crude oil generated from the Permian source rocks in the Changji Sag formed the Cretaceous reservoir first,and later entered the Shawan Formation reservoir under the fault adjustment;the Jurassic source rocks migrated to the second member of Shawan Formation through fault system and thick sandbody;the oil and gas of Jurassic source rock in Sikeshu Sag was transported to the first member of Shawan Formation in southwestern China.