球面波叠前地震记录的合成方法

Method of generating prestack synthetic seismograms of spherical wave

叠前地震数据的反演需要以某种正演算法为基础。采用反射率法计算层状介质的球面波叠前地震记录,在平面纵波入射和全固态介质假设条件下,推导了水平层状介质中的频率慢度域纵横波反射、透射系数公式,给出了τ-p域的平面波合成记录的实现方法,并利用广义Filon积分方法对频率慢度域的反射率函数进行了积分变换,同时还对全反射现象和截断效应给出了相应的解决方案。计算结果表明,利用反射率法可以得到地震波场的完全解,包括地震波在地层中传播时形成的一次波、多次波和转换波信息。模型试算和实际应用均表明该方法能够提高计算速度和计算精度。

The inversion of prestack seismic data was conducted on the basis of some forward algorithms, The reflectivity method was adopted to compute the prestack synthetic seismograms in layered medium. Formulas for calculating reflection and transmission coefficients of P and S waves in frequency-slowness domain were derived on the assumptions of plane Pwave incidence and full mild medium. Method of generating plane-wave synthetic seismograms in the intercept-time ray-parameter （ r-p ） domain was developed, Reflectivity function in frequency-slowness domain was transformed to time-space domain by generalized Filon integration method and prestack synthetic seismograms were generated. The solution to critical problem and truncation effect was presented and the quality of record was improved. The modeling of full wave field including the primary reflection, multiple and converted wave was got. The numerical test and real application show that the computation speed and accuracy can be increased by the reflectivity method, and which lays solid foundation for prestack inversion.