VTI介质角度域转换波高斯束偏移成像方法研究

转换波偏移可以利用纵横波波场信息，得到高分辨率的成像结果，从而为油藏描述提供高质量的地震资料.目前的研究主要是利用纵波波场信息进行偏移成像，然而，传统的纵波方法在复杂探区成像时具有一定的局限性.为此，本文在各向异性介质声波射线追踪算法的基础上，推导出各向异性介质转换波射线追踪方程，发展了一种转换波射线追踪算法；并将研究的追踪算法应用到偏移成像中，提出了一种各向异性VTI介质角度域转换波高斯束偏移成像方法.通过各向异性VTI介质断块模型和复杂构造模型试算，说明了本文方法的正确性和有效性.模型试算的结果表明，在考虑地下各向异性时，本文研究的方法具有更好的成像效果，提取的角道集结果可以为偏移速度分析提供依据.

Angle domain converted wave Gaussian beam migration in VTI media

As targets are highly variable complex reservoirs, the difficulty of hydrocarbon exploration has been gradually increasing. Taking into account the wavefield information of both primary and shear waves, images with high resolution could be obtained by using the migration method of converted waves, which can help lithology identification, reservoir prediction and reservoir characterization. However, by far only the information of the primary wavefield is widely utilized in migration, which results in many drawbacks of the primary migration method especially when the prospecting area is complex.#br#On the basis of the anisotropic acoustic ray tracing algorithm, we derive the equations and develop a ray tracing algorithm of converted waves for an anisotropic medium. Furthermore, we summarize the imaging formula of converted waves in the angle domain for this medium.#br#Using this algorithm, we propose a Gaussian beam migration imaging method of converted waves in the angle domain for anisotropic VTI media. Numerical experiments on fault-block and complex structural models have verified its accuracy and efficiency. Besides, the proposed method is not only more efficient compared with the anisotropic Gaussian beam migration imaging method put forward, but also more accurate in comparison with the isotropic Gaussian beam migration imaging method. Moreover, the result of angle domain common imaging gathers could also provide useful information for migration velocity analysis.