利用地震和三维数值模拟研究鄂尔多斯盆地红河油田的走滑断裂活动及应力场演化

Using seismic data and 3D numerical simulation to study strike-slip faulting and stress field evolution in Honghe Oilfield,Ordos Basin

以鄂尔多斯盆地红河油田精细地震构造解释为基础,结合南缘秦岭和西缘六盘山的构造演化史,并采用有限差分软件开展两期构造叠加的大应变数值模拟实验,探讨红河油田的走滑断裂活动及应力场演化。结果表明,北西走向的玉都断裂带先活动,受到基底断层控制而发育单断式左行走滑,应在晚侏罗世—早白垩世活动,其动力学背景是秦岭北缘不同块体之间往北西方向的差异挤压,活动之时玉都断裂带附近最大主应力方向为北东东向;北东东向弥散式断层后活动,受到六盘山冲断带向东挤压过程中南北差异的影响而发生左行走滑,在早白垩世晚期或新生代活动,活动之时最大主应力为北东向(N36°~69°),平均N53°。研究结果对本地区的断裂预测提供了新的约束,亦可为鄂尔多斯盆地其他油田的断裂研究提供借鉴。

This work focuses on the strike-slip faulting activity and stress field evolution in Honghe Oilfield,Ordos Basin.With the finite difference software,a series of 3D numerical models were constructed to investigate the two stages of structural superposition.Constrained by the refined seismic structure interpretation and the tectonic evolution of Qinling Mountain in the south and Liupanshan Mountain in the west,the model results indicate that the NW trending Yudu Fault developed first and was controlled by the sinistral strike-slip of basement fault.The Yudu Fault is supposed to be active in the late Jurassic-early Cretaceous,which is mainly attributed to the northwestward compression among different blocks in the northern margin of the Qinling Mountains.The maximum principal stress near the Yudu Fault Zone was oriented NEE during faulting.Subsequently,the NEE trending faults developed and were subjected to distributed sinistral strike-slip faulting during eastward compression of the Liupanshan thrust belt.These faults developed in the late Early Cretaceous or the Cenozoic.The maximum principal stress was oriented in the range of N36°~69°with an average of N53°.This study provides a new constraint on the fault prediction in this area,and also sheds new light on faulting dynamics in the other oilfields in the Ordos Basin.