应用正演模拟分析近地表黏弹性对深层缝洞储层地震波衰减及成像的影响

Nearsurface visco-elastic medium influences on wave attenuation and imaging of deep fractured-vuggy reservoir with forward modeling

近地表沙层的黏弹特性引起的地震波能量及频率的吸收衰减不容忽视。本文基于黏弹性介质波动方程正演模拟技术,研究了近地表不同Q值情况下地震波穿过黏弹介质后的地震波场特征,通过波场频谱特征分析了影响地震波能量及频率吸收衰减的因素,即Q值越小、激发子波的主频越高、传播距离越远的地震波能量及主频吸收衰减越严重。在此基础上建立起伏地表沙层缝洞型模型,研究近地表沙层对中深部储层反射波的衰减及对缝洞型储层成像的影响,对实际地震资料的振幅、频率的恢复补偿以及提高分辨率具有一定意义。

Seismic absorption and attenuation of energyand frequency caused by visco-elasticity nearsurface sand layers cannot be ignored.In this article,we discuss seismic wave field generated by seismic wave travelling through visco-elastic medium with different Qby forward modeling based on visco-elastic wave equation.We also analyze factors affecting seismic energy and frequency absorption and decay through wave field spectral analysis.The smaller the Qvalue is,the higher dominant frequency the wavelet has,seismic energy and frequency absorption and decay are more serious and with the propagation distance increases.Finally,building fractured-vuggy models,we analyze nearsurface sand influence on wave attenuation and deep fractured-vuggy reservoir imaging.It is proved that this meaningful work is helpful for amplitude and frequency compensation and data resolution enhancement.