AVO Inversion Method Of P-S Velocity Ratio In Carbonate Reservoir

After years of development,seismic inversion has become one of the core technologies of oil and gas seismic exploration.Through inversion technology,we can obtain the elastic and physical properties of underground strata conveniently,efficiently and stably.AVO inversion is an important part of seismic inversion and an effective method to obtain formation parameters.In inversion problem,the ill condition of inversion result is the main problem to be solved.The purpose of this paper is to propose an effective AVO inversion method,so as to reduce the parameter estimation error in the inversion process,improve the stability of the three parameter inversion problem,and apply to the identification of oil and gas reservoirs.AVO is a tool to estimate the properties of reservoir rocks and fluids and to predict oil and gas by using the variation of amplitude with offset.The basic theory of AVO technology is Zoeppritz equation,but the traditional inversion technology is based on various linear or quasi linear approximations of the nonlinear equation.In this paper,based on the previous studies,a more accurate Zoeppritz equation approximation is used for inversion study,and the formation parameters such as P-wave velocity,S-wave velocity and density are estimated effectively.The velocity ratio of P-wave and S-wave mentioned in the formula is convenient for iteration and can be used to identify oil and gas reservoirs.In order to effectively reduce the ill posed problems in AVO inversion process and improve the continuity of transverse interface and the vertical resolution of space.In this paper,a damped least square hybrid algorithm based on boundary constraint is proposed to solve the objective function.The traditional and effective linear AVO inversion is used externally,the Jacobian matrix is constructed and the model is updated,and the nonlinear iterative equation is used internally to refine the data.Numerical experiments show that this method is feasible and has achieved some practical results.