Elastic Wave Reverse Time Migration Of Decoupling Equation Based On Improved Cosine Combined Window Function

As the exploration continues to deepen,the petroleum industry's requirements for speed modeling accuracy and imaging quality are gradually increasing.However,some new problems should be solved urgently,such as how to accurately identify rocks and fluids,crack detection,and so on.With the continuous development and improvement of computer technology at this stage,we can achieve seismic big-data calculations that were not possible previously.The reverse time migration(RTM)of the elastic wave vector wavefield can comprehensively use the vertical and horizontal field information to image the underground space,and there is no angle limitation for the imaging medium,which can more clearly image the complex structure.So it is very important to deepen the research of RTM of elastic waves.The algorithm of solving the wave equation,which affects the accuracy and efficiency of imaging directly is the most important thing for RTM.The accuracy of elastic wave imaging depends largely on the separation effect of the elastic wave field.Therefore,based on the above problems,some research had been down as follows.1.In this paper,the cosine combined window function(CCWF)used in harmonic analysis of the power system was introduced.Then we obtained optimal finite-difference schemes based on improved CCWFs.Through numerical simulation,we can know that the optimized finite-difference operator can greatly improve the accuracy of elastic wave numerical simulation,and can greatly increase the calculation speed of numerical simulation and improve the calculation efficiency.2.Then,we introduced the separation of the elastic wave vector wave field.It mainly introduces the wavefield separation technology under a homogeneous medium.For the wavefield separation of isotropic media,we compare the advantages and disadvantages of the traditional Helmholtz equation separation method and the decoupling equation separation method.And introduced the wavefield separation strategy in anisotropic media.3.Finally,we apply the optimized finite-difference operator to the vector wavefield separation algorithm of the decoupling equation to greatly improve the imaging accuracy.Numerical tests show that the imaging accuracy and clarity of the reverse-time migration based on the new algorithm have been significantly improved.