Pseudo acoustic equation for TI medium attenuation based on the GSLS model
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摘要: 随着计算机硬件技术的发展以及高分辨率勘探需求的增加,我们希望能够更准确地模拟地下介质,得到更丰富的地层信息.然而,传统的声学假设并不能描述实际地层所存在各向异性和黏滞性,使得成像分辨率较低.为了实现深部储层的高精度成像,本文同时考虑了介质的各向异性和黏滞性,从TI介质弹性波的基本理论出发,结合各向异性GSLS理论,并通过声学近似方法导出基于GSLS模型的各向异性衰减拟声波方程.数值模拟表明该方程既能准确地描述各向异性介质下的准P波运动学规律,又能体现地层的吸收衰减效应;模型逆时偏移结果表明,在实现成像过程中考虑各向异性和黏滞性的影响,能对高陡构造清晰成像,且剖面振幅相对均衡,分辨率较高.Abstract: It is well known that the underground medium is far from being an acoustic material. Neglecting anisotropy and attenuation in seismic wave propagation can result in inaccuracy imagery, such as problems of diffracted wave convergence and seismic wave attenuation. So it is urgent to take anisotropy and viscosity into account, and necessary to consider both of the characteristics in practical production. In this paper, starting from the basic theory of elastic waves in TI media, and introducing the GSLS theory of isotropic medium into anisotropic material, we derive a pseudo acoustic equation for anisotropic attenuation based on the GSLS model by the acoustic approximation method. The numerical results show that the VTI viscoacoustic wave equation can not only describe the propagation of wave in anisotropic media accurately, but also reflect the effects of absorption and attenuation. Reverse time migration of the HESS model on the VTI medium shows that the attenuation pseudo acoustic equations can image more clearly, such as the complex structure with high steep dip angles, make deep amplitude distribution more balanced, and obtain more accurate and reliable amplitude imaging profiles.
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