Research On Seismic Modeling Method Of Heterogeneous Two-phase Medium With Rock Physics

Two-phase medium rock physical basis is the important link between elastic properties and reservoir physical properties,which mainly studies the effect of petrophysical parameters to rock elastic parameters and plays an important role in the seismic forward modeling and migration results.petrophysical parameters includes rock constituents,porosity,modulus,density,fluid type and saturation,etc.Rock physical basis regards the ideal rock physics model as two-phase model under certain assumptions,then makes the relationship between elastic parameters and rock matrix,framework and fluid properties.Combination of rock physics and seismic forward modeling can help studying the seismic wave propagation in heterogeneous complex medium and has important significance to structure image and reservoir prediction.Accuracy and efficiency are key problems in forward modeling,how to improve them has been highly concerned.Numerical dispersion is connected with time step,spatial step,seismic wave velocity,direction of propagation,wave length,differential coefficients and so on.This paper aims at ten order space staggered-grid finite difference algorithm,using the least square method by changing the integral interval to calculate a series of differential coefficients of the first-order spatial derivative to analyzes dispersion relations of the differential coefficients with the traditional method.This paper selects the least square method of the best result and compares it with the traditional method.Numerical dispersion analysis and elastic wave field simulation analysis show that in the same conditions of elastic parameters and discrete parameters,the least square method using the best integral interval can effectively suppress numerical dispersion and has higher precision than the traditional Taylor-series method.Combination of two-phase medium rock physics and forward modeling can help studying the seismic wave characteristics more accurately.Based on Biot theory,this article start from the one-order stress-velocity wave equation and use the new differential coefficients to simulate the two phase medium with high-order staggered-grid finite difference algorithm.The forward modeling algorithm was applied to homogeneous model to analyze the effects of the petrophysical parameters,it then was applied to two-layer medium aimed at analyzing the reflection and transmission of the interface.Finally,the forward modeling algorithm was applied to the heterogeneous complex medium.The results provide theoretical support for exploration of heterogeneous reservoirs in reality.