叠前时间偏移在三维转换波资料处理中的应用

在转换波资料处理中，共转换点道集的抽取和倾斜时差校正等是处理的难点，而叠前克希霍夫时间偏移技术不需要进行共转换点道集抽取、倾斜时差校正和叠后偏移等处理，就能实现三维转换波资料的全空间精确成像。为此，探讨了叠前克希霍夫时间偏移技术在转换波资料处理中的应用。论述了建立叠前时间偏移初始速度场的方法原理——根据转换波的特点，在转换波散射旅行时方程中引入各向异性参数，针对转换波速度和各向异性参数，利用“三谱”分析技术建立叠前时间偏移初始速度场；论述了建立叠前时间偏移速度场的方法原理——通过对共成像点道集的偏移、反正常时差校正处理、交互迭代解释速度和各向异性参数等，确定最佳的偏移速度场。将该技术应用于XC气田的三维三分量转换波资料处理，处理后的三维转换波叠前时间偏移剖面成像清晰，归位准确，地质形态细致。

Application of pre-stack time migration in 3-D converted-wave data

In convertea-wave data processing, CCP binning ana DMO are the difficult problems. However, the pre-stack Kirchhoff time migration can realize the full space imaging for 3D converted-wave without using CCP binning, DMO and post-stack migration processing. So the application of pre-stack time migration in 3D converted-wave data processing was discussed. The principles of establishing the initial velocity field for pre-stack time migration were studied, which are 1) introducing the anisotropic parameters in the scatter travel time equation based on the characteristics of converted-wave, and 2) using three spectrums analysis method to build the initial velocity field for pre-stack time migration. The principle of establishing the initial velocity field for pre-stack time migration processing was probed. In this principle, the optimal migration velocity field is obtained by mutual iterative interpretation for velocity and anisotropic parameters after processing of migration and in-verse-NMO on CIP gathers. The processing method has been applied to process the 3-D three-component converted-wave data in XC gas field. After processing, the sections of pre-stack time migration have clear images, exact location, and fine geologic configuration.