井中地震三维高效黏声逆时偏移成像方法及应用

3D efficient visco-acoustic reverse time migration in borehole seismic and its application

井中地震是井中激发地面接收的一种新型地震采集方法,与地面地震相比,具有采集成本低,作业效率高的优点.此外,井中地震资料信噪比高、频带宽、波场丰富,可实现井周小尺度构造精细成像.在油藏开发中,井中地震可实现油藏描述与监测.鉴于上述原因,近年来,井中地震受到业内越来越多的关注.然而,井中地震震源能量弱,地层吸收衰减效应的影响强于地面地震.因此,需要发展针对性的井中地震衰减补偿偏移成像方法.本文基于Kelvin-Voigt模型推导新的振幅衰减和相位频散解耦的黏声波动方程,通过改进激发振幅成像条件,实现高效的井中三维地震黏声逆时偏移成像方法.此外,本文采用时变低通滤波器压制高波数噪声,提升黏声逆时偏移方法的稳定性.数值算例及实际资料应用表明,本文提出的井中三维黏声逆时偏移成像方法计算效率高、稳定性好,实用化潜力大.

At present,complex oil and gas reservoirs have the characteristics of thin reservoir,wide distribution and subtle occurrence,which poses a great challenge to the high-precision imaging of small-scale structures in the reservoir.Compared with surface seismic,borehole seismic theoretically has the advantages of high signal-to-noise ratio,wide frequency band,rich wavefield information and strong reservoir identification,and can produce fine reservoir images around the well.However,the source energy of borehole seismic is weak,and thus the absorption attenuation effect of subsurface media is stronger than that of surface seismic.Therefore,it is necessary to develop an attenuation compensation migration imaging method for borehole seismic.Based on Kelvin-Voigt model,a new viscoelastic wave equation decoupled by amplitude attenuation and phase dispersion is derived in this paper.By modifying the excitation amplitude imaging condition,an efficient 3D viscoacoustic reverse time migration imaging method for borehole seismic is implemented.In addition,a time-varying low-pass filter is used to suppress high wavenumber noise and improve the stability of the proposed viscoacoustic reverse time migration method.Numerical examples and field data results show that the proposed 3D viscoacoustic reverse time migration method has high calculation efficiency,good stability and great practical potential.