玛湖西环带高角度断裂成因与控藏作用

Deformation Mechanism and Petroleum Accumulation of the High Angle Faults in the Western Circle Zone of Mahu Depression,Junggar Basin

通过高密度三维地震资料精细解释,在准噶尔盆地玛湖凹陷西环带发现众多高角度断层,断层剖面组合为复合型与单一型,平面组合为斜交式与平行式。规模大、压扭强的断层,分支多,剖面组合呈"花状"构造;规模小、压扭性弱的断层,常单独发育。成因机理分析表明,高角度断层是达尔布特断裂的派生构造,属Sylvester简单剪切模式中R′剪裂面,并得到物理模拟实验证实。高角度断层与油气运聚关系极密切,形成期与油气生成期匹配合理,构成油气垂向运移的良好通道。静止期形成有效的油气圈闭,高角度断层围限的断块、断鼻是下一步油气勘探的重点目标。

According to the high-resolution 3D seismic interpretation,a series of high angle faults are developed in thewestern circle zone of Mahu depression.In section view,these high angle faults present single or combination distribution;while in plain view,they present oblique or parallel distribution. The large shearing fault branches several splays to formflower structures in section view; whereas the smaller shearing fault usually presents single fault development. It is suggestedthat the high angle faults are accommodation structures of the Daerbute fault, corresponding to the R’shearing inthe Sylvester shearing model,which is also verified by the physical experiments. These high angle faults can be good conduitsfor the vertical migration of petroleum, as the deformation timing is properly matched with the hydrocarbon generationtiming. During stable period, the high angle faults present good sealing properties to form effective hydrocarbontraps. Therefore, the fault blocks and fault noses constrained by these high angle faults can be emphasizes in the followingpetroleum exploration.