The Approximate Algorithm Of Seismic P-Wave And S-Wave Reflection Coefficients And Its Analysis Of Applicability In Shuxi Gas Reservoir As Example

AVO(Amplitude versus offset), which is a method in searching for oil and gas seismic exploration using the relationship between seismic reflection amplitude and its offset, has been developed quickly and used widely in seismic wave research and actual production in recent years.AVO forward modeling study, as a basic and essential part of AVO technology, plays an important role in AVO technique. As with other methods of seismic model, AVO forward model has many features as follows. Firstly, based on the determination and independence of the parameters, AVO forward model facilitates the design objective field observation system for the right selection. Secondly, according to the rigorous and detailed forward modeling, AVO response model is able to analysis and calculate depending on the curve type of AVO response in real area and judge the feasibility of objective layer of oil and gas. Thirdly, vast majority of models and technologies to retrieve formation parameters are based on AVO forward modeling technique when extracting formation parameters.AVO technology starts from the classical Zoeppritz equation as the theoretical basis,and the equation can be established the relationships between the parameters of P-wave and S-wave on both sides of the interface,which can reflect energy transfer in the medium. But on account of so many parameters in the equation and the complicated calculation, the practical application of Zoeppritz equation is not easy to use. In order to minimize the complex of equation which have effects on forward simulation,in this paper we contrast and analyze the approximation equations of Zoeppritz equation using Ostrander model to fit each solution of approximation equation. On the one hand,results show that different forward approximate equation has a different scope, and most of the approximation equations in the small angle range below the critical angle have high fitness. On the other hand, fitting equation will change with the alter of parameters in models.Considering that the fitness of forward approximation equation in the angle which is higher than the critical angle is not very ideal, this paper starts from the exact solution of Aki and Richards equation in appropriate parameter conditions, and it offers the approximate equation of P-SV wave reflection coefficient at large angle. Then the curves of reflection coefficients and AVO sets of the models are obtained by programming calculation. On the basis of the study the forward models is extended to Suxi area to analyze and compare with each other, which can reflect the influence of the wide-angle model in the actual formation production. Finally according to the chart the situation of different strata in Suxi region is summarized and the feasibility of AVO forward technical is retrospectively analyzed.