准噶尔盆地中拐凸起南部构造演化及油气地质意义——以中佳地区下二叠统佳木河组为例

Structural evolution and geological significance of hydrocarbons in the south of Zhongguai Uplift,Junggar Basin:a case study of the Jiamuhe Formation of the Lower Permian in Zhongjia Area

准噶尔盆地中拐凸起南部中佳地区佳木河组多口井获工业气流,断裂对油气影响显著。利用三维地震和钻井资料,采用平衡演化剖面技术,分析中拐凸起南部断裂发育特征及演化过程,建立断裂与下二叠统佳木河组二段油气成藏成储的联系。结果表明:中拐凸起南部主要发育逆冲断裂、走滑断裂和正断裂。逆冲断裂在早二叠世晚期开始发育,晚二叠世停止发育,对下二叠统佳木河组二段改造作用显著;走滑断裂集中在三叠纪发育,对地层的改造作用有限;正断裂在三叠系层内发育,未改造佳木河组。研究区构造演化可划分为4个阶段:石炭纪—二叠纪逆冲改造阶段、三叠纪—侏罗纪压扭走滑阶段、侏罗纪—白垩纪隆升剥蚀阶段和白垩纪—新近纪沉积掀斜阶段。石炭纪—二叠纪是断裂发育的主要时期;佳木河组二段优质储层主要发育于近断裂位置,断裂发育位置与研究区单斜构造共同控制油气圈闭的分布和形成;断裂与不整合分别为油气提供纵向和横向运移通道,将油气藏由北向南划分为低饱和度气顶大油环区、小气顶大油环区、小油环大凝析气藏区、无油环凝析气藏区及纯气区5种类型。该结果为中拐凸起南部中佳地区下二叠统佳木河组油气勘探部署提供指导。

Commercial gas flow has been obtained of Jiamuhe Formation in Zhongjia Area,Southern Zhongguai Uplift,Junggar Basin.The production practice shows that the fault has a significant impact on oil and gas in this area.Based on the existing research results,using the data of 3D seismic and drilling and the technology of balanced evolution profile,the development characteristics and evolution process of the fault of the Southern Zhongguai Uplift are analyzed,and the relationship between the fault and the hydrocarbon accumulation of the second member of the Lower Permian Jiamuhe Formation is established.The research shows that the thrust fault,strike-slip fault and normal fault are mainly developed in study area.The thrust fault began to develop in the late stage of Early Permian and stopped in the Late Permian,which had a significant transformation effect on the second member of the Lower Permian Jiamuhe Formation.The strike-slip faults are concentrated in the Triassic,and the transformation of the strata is limited.The normal fault is only developed in the Triassic strata,and the Jiamuhe Formation is not reformed.The tectonic evolution of the study area can be divided into four stages:Carboniferous-Permian thrust transformation stage,Triassic-Jurassic torsional strike-slip stage,Jurassic-Cretaceous uplift and denudation stage and Cretaceous-Neogene sedimentary tilt stage.Carboniferous-Permian is the main period of fault development.The high-quality reservoirs in the second member of Jiamuhe Formation are mainly distributed in the near-fault position,and the fault and the monoclinic structure in the study area common control the distribution and formation of oil and gas traps.Faults and unconformities provide vertical and horizontal migration channels for oil and gas.At the same time,from north to south,oil and gas reservoirs are divided into five types:low saturation gas cap and large oil ring area,small gas cap and large oil ring area,small oil ring and large condensate gas area,no oil ring condensate gas reservoir area and pure gas area.The research results can provide guidance for the next exploration and deployment of the Lower Permian Jiamuhe Formation in Zhongjia Area,Southern Zhongguai Uplift.