尼日尔Trakes斜坡走滑断裂特征及其对油气藏的控制作用

Characteristics of strike-slip fault and its control on oil and gas accumulation in the Trakes slope,Niger

因断裂发育模式及展布规律不清楚,尼日尔Trakes斜坡圈闭识别困难,油气勘探一直未取得突破。为此,利用三维地震资料,通过构造导向滤波及本征值相干等断裂精细刻画技术,明确了断裂展布特征及成因。结果表明:研究区发育NNW-SSE和NW-SE向两组共轭的走滑断裂,在地震剖面上呈花状或半花状。其中,NW-SE向的走滑断裂为R右行同向剪切破裂形成的断裂,控制了Trakes斜坡南北分带的构造格局;NNW-SSE向的走滑断裂为R′左行反向剪切破裂,与NW-SE向断裂配合,控制了Trakes斜坡构造圈闭的分布。另外,走滑断裂也是油气自下向上运移的重要通道,对油气成藏具有控制作用。

Due to the unclear fault pattern and distribution rules,it is difficult to identify traps in the Trakes slope,Niger,and thus there is no breakthrough in oil and gas exploration.Therefore,based on 3D seismic data,this paper clarifies the distribution characteristics and formation mechanism of faults by fine characterization techniques for faults such as constructing guided filtering and eigenvalue coherence.Results show that two groups of NNW-SSE and NW-SE conjugate strike-slip faults are developed in the studies area,with floral or semi-floral characteristics in seismic profiles.The NW-SE strike-slip fault formed by the simultaneous shear rupture on the right side of R controls the tectonic pattern of the north-south zoning of this slope.The NNW-SSE strike-slip fault is an R′left-lateral reverse shear fracture,which,in conjunction with the NW-SE fault,controls the trap distribution on the Trakes slope.Additionally,strike-slip faults are also an important channel for hydrocarbon migration from bottom to top,controlling hydrocarbon accumulation.