沃尔什函数法叠后相对层速度反演

Poststack inversion for relative interval velocity using Walsh function

江汉石油学院, 江陵434102

Department of Geophysical Exploration, Jianghan Petroleum Institute, Jianglin 434102

沃尔什(Walsh)函数法叠后相对层速度反演是以叠后地震道的褶积模型为基础的。把褶积方程改写为第Ⅰ类Fredholm积分方程, 利用沃尔什函数来求解积分方程中的未知函数──声阻抗, 再将声阻抗转换为相对层速度。该方法反演出的层速度界面突出, 分层明显, 对确定储层厚度十分有利。该方法抗噪能力强, 运算速度快, 与道积分法相比, 它具有更好的地质现象(断层、不整合等)表现能力, 是目前较为理想的一种将界面信息转换为地层信息的方法。

Poststack relative interval velocity inversion using Walsh function is based on the convolution model of poststack seismic traces. It first writes a first-category Fredholm integral equation for the convolution equation, then determines the unknowns - acoustic impedances from the integral cquation using Walsh function and finally transforms the acoustic impedances into a set of relative interval velocities. The resulting interval velocity interfaces look quite distinct in stratification, whick is definitely a great help to the determination for reservoir thickness. The method proves powerful in noise immunity and efficient in computation. Compared to the trace integral method, it is capable of well-delineating geological structures (e. g. faults and unconformity interfaces), and is thereforc an idcal method for transforming interace information into stratigraphic information.