基于交错网格有限差分法的断面波叠前时间偏移成像影响因素正演分析

Forward analysis of the influencing factors in prestack time migration imaging of fault surface waves based on the staggered-grid finite-difference method

断层和断裂带的有效识别是地震资料解释中的重要环节,断层在地震信号响应中以断面波的形式体现,因此断面波成像的质量关系到断层的精细识别与刻画.本文利用精度较高的交错网格有限差分正演模拟方法对断面波成像的影响因素进行了正演研究,主要正演分析的参数包括采集因素中的电缆长度和采集方向,地质因素中的断层倾角、断距、反射系数,以及处理因素中的偏移方法等几个方面.通过正演论证得出:采用合理的采集参数能够提高断面波的照明度;有效结合地质因素能够提高断面波的解释精度;利用合理的偏移方法能够使断层归位更加准确,断面波有效成像.基于以上结论,对于断面波的精确识别与刻画,应综合采集因素,处理因素及地质因素,只有这样才能提高断层的解释精度,有效减小解释误差.

Identification of faults is an important step in seismic data interpretation. In seismic signal response, a fault can be recognized by fault surface waves, so the quality of the imaging of fault surface waves determines how to characterize the fault. In this paper, the influence factors of sueh imaging is studied by forward modeling using the staggered-grid high-order finitedifference method. The parameters in this modeling include the cable length and acquisition direction, the formation dip and reflection coeffieient and the migration method. The results of forward modeling demonstrate that selecting the reasonable acquisition parameters can improve the illumination of fault surface waves. Combining with the geological factors can enhance the accuracy of fault interpretation. Using reasonable migration methods can make the fault homing more accurate. Based on the above conclusions, for accurate identification and characterization of fault surface waves, we should integrate acquisition, treatment and geological factors. Only in this way can the interpretation accuracy of faults be improved greatly.