Study On Methods Of Viscoelastic Reverse Time Migration

As exploration targets become more complex,New requirements are placed on seismic exploration imaging methods and technologies.Traditional underground structure imaging methods are far from meeting the needs of exploration and production.In petroleum exploration,the effects of deep migration imaging have been limited.One of the most important points is the absorption and attenuation effect of the formation on seismic waves.Because the underground medium itself has very strong viscous characteristics,the traditional migration imaging method uses Hooke's law as the assumption of underground rock physics,which is inconsistent with the actual situation,which will cause a certain deviation in the imaging results.In order to solve this problem,a viscous reverse-time migration imaging method has been proposed to effectively solve the problem that deep structures cannot be accurately imaged due to subsurface absorption attenuation.In this paper,based on the theory of viscoelasticity,combined with two viscoelastic models of standard linear solid model and constant Q model,the method of viscoelastic reverse time migration imaging is analyzed and studied.Firstly,the high-precision wave field simulation is analyzed and studied.For the standard linear solid model and constant Q model,the high-order finite difference method and the pseudo-spectral method are used to solve the numerical value.And further analyze the factors that determine the accuracy of the two methods,and compare the calculation accuracy and calculation efficiency of the two models;Then the viscoelastic wave field separation algorithm is studied,and the four P and S wave field separation methods and the two up and down wave separation methods are implemented and compared to obtain the most accurate separation method;For the viscoelastic reverse time migration imaging method,this paper proposes a stability compensation method based on constant Q equation,based on the Predictor-Corrector algorithm to solve the problem of high frequency noise suppression in the wave field compensation process,so as to obtain higher accuracy and signal to noise ratio imaging results;Aiming at the method of viscoelastic least squares reverse time migration imaging,the least squares correlation equation is derived,and the flow of least squares inverse time migration imaging under viscoelasticity is obtained.Through the model test of horizontal layered and complex structures,it is concluded that the viscoelastic reverse-time migration imaging method can effectively improve the imaging effect and accuracy of high-attenuation structures,which is very important for the development of high-precision imaging methods for oil and gas.It has a positive role in ensuring national energy security.