不同边界条件下的二维声波方程数值模拟

摘要

地震波场数值模拟是研究波动现象的重要手段之一,对油气田的勘探和开发具有重要意义.数值模拟过程中,需要通过添加边界条件来尽可能消除由于截断所产生的边界反射.选取雷克子波作为震源项,分别建立均匀及层状地质模型,拟定合适的波场模拟参数,实现了不同边界条件下的二维声波方程数值模拟.利用数值模拟得到的波场快照和地震记录直观地对比分析不同边界条件对边界反射的消除效果,认为透明边界条件(TBC吸收边界条件)和Clayton-Engquist边界条件(CE吸收边界条件)都能够较好地消除边界反射.最后提出了一种组合边界条件的方法.%Numerical simulation of seismic wave field is one of the important means to study the fluctuation phe-nomenon , which is very important for the exploration and development of oil and gas field .In the numerical simula-tion process, it is necessary to eliminate the boundary reflection due to the truncation by adding the boundary condi -tion as much as possible .The Ricker is selected as the source , and the uniform and stratiform geologic model is es-tablished respectively .The appropriate wave field simulation parameters are developed to realize the numerical sim-ulation of the two-dimensional acoustic equation under different boundary conditions .Wavelet snapshots and seismic records obtained by numerical simulation are used to visually analyze the elimination effect of boundary conditions on boundary reflections .It is considered that the boundary condition is better to eliminate the boundary condition ( hereinafter referred to as TBC absorption boundary condition ) and Clayton-Engquist boundary condition ( hereinaf-ter referred to as CE absorption boundary condition ) .Finally, a method of combining boundary conditions is pres-ented.