准噶尔盆地乌夏地区油气输导体系与成藏模式

HYDROCARBON CONDUCTING SYSTEM AND ACCUMULATION MODEL IN WUERHE-XIAZIJIE AREA OF JUNGGAR BASIN

乌夏地区在二叠系、三叠系和侏罗系3个层系的10个层组发现了油气,依据成因和遮挡条件,将油气藏分为背斜型、断块型、不整合型、稠油封堵型、岩性尖灭型和断层-岩性型6种类型。多期的构造运动,在该区形成了多期断裂体系、多个不整合及多套连通砂体,构成了立体网状输导体系。其中,中、下三叠统砂体发育广泛,连通性最好;侏罗系底部不整合分层结构明显,是油气运聚的良好场所;印支期断层活动与烃源岩排烃相匹配,构成垂向运移通道,印支期后活动减弱,油气被阻挡在断裂下盘成藏。根据油气来源、运移通道与方向、成藏期次等,将乌夏地区划分为"一"字型成藏模式、"Y"字型成藏模式、"Z"字型成藏模式和"多"字型成藏模式4种。

In Wuerhe-Xiazijie Area,oil and gas have been discovered in ten formations of Permian,Triassic and Jurassic strata.According to the origins and sealing conditions,the reservoirs can be divided into six types,they are anticline reservoirs,fault block reservoirs,unconformity reservoirs,heavy oil sealing reservoirs,lithology-pinchout reservoirs and fault-lithologic reservoirs.Because of the multi-period tectonic movements,multi-period fault systems,many unconformities and connected sand bodies,which constitute the three-dimensional net migration systems,were formed.Sand bodies in middle and lower Triassic strata are extensively developed and best connected.Unconformities at the bottom of Jurassic strata,which have good layered structures,are good places for hydrocarbon migration and accumulation.Fault activities in Indo-Chinese epoch,which were in the same period with the hydrocarbon expulsions from source rocks,created the vertical migration pathways,and the fault activities decreased after the Indo-Chinese epoch when oil and gas were trapped in the lower wall of the faults.In terms of the sources of oil and gas,migration pathways and directions and the reservoir-forming periods,the accumulation models can be divided into four types:'一'-like accumulation models,'Y'-like accumulation models,'Z'-like accumulation models and '多'-like accumulation models.