基于黏声介质的角度域高斯束逆时偏移方法研究

Angle-domain reverse time migration with Gaussian beams in viscoacoustic media

高斯束逆时偏移是一种兼具计算效率和成像精度的深度域成像方法,能够面向目标成像.地下介质中黏滞性普遍存在,利用传统各向同性或完全弹性的成像方法处理黏滞性探区的数据会降低分辨率,并导致成像位置不准确和振幅欠估计等问题.本文在高斯束逆时偏移的基础上,通过对震源点和检波点处的波场进行衰减补偿,并结合高斯束求解时的角度信息,实现了黏声介质角度域高斯束逆时偏移方法.最后通过模型和实际资料试算对本文方法的正确性和适用性进行了验证.试算结果表明:相比于声波高斯束逆时偏移,本文方法能够对黏滞性引起的吸收衰减进行有效补偿,同时提取的角度域共成像点道集(ADCIGs)不仅可以用于分角度叠加成像压制成像噪声,而且能够为后续的偏移速度分析提供支撑.

Reverse time migration with Gaussian beams is a depth domain imaging method with computational efficiency and imaging accuracy,which can be used for target-oriented imaging.The viscosity widely exists in the subsurface media,the use of traditional isotropic or fully elastic imaging methods to process the viscous data will cause inaccurate imaging positions and under-estimation of amplitude.This paper combined the angle information in the Gaussian beam calculation and compensated the absorption attenuation of the wavefields at the source and receiver points,then realized an angle-domain reverse time migration with Gaussian beams in viscoacoustic media.The correctness and applicability of the proposed method are tested by the numerical tests.The trial results show that compared with the acoustic reverse time migration with Gaussian beams,the proposed method can effectively compensate the absorption attenuation of the viscoacoustic media.Meanwhile,the extracted Angle Domain Common Imaging Point Gathers(ADCIGs)can be used not only for superimposition imaging to suppress the imaging noise,but also to provide support for migration velocity analysis.