Oil And Gas Identification Based On Two-phase Medium Asymptotic Model

Reservoir identification is a very important technology in seismic exploration.At home and abroad,there are many successful examples in this work.However,previous reservoir fluid identification is based on seismic elastic waves of sandstone reservoirs and carbonate reservoirs.These theories apply only to single-phase media reservoirs,but hydrocarbon reservoirs and many sedimentary rocks are fluid-saturated Of the two-phase medium reservoir.The elastic properties of these biphasic media can be described by the porosity elasticity theory.The classical Boit’s porosity elasticity theory is not suitable for seismic bands and is only applicable to bands above the Biot characteristic frequency,typically 0.1 MHz or higher.In addition,most pore elasticity studies focus on velocity dispersion and attenuation.Thus,it is desirable to obtain a simple form of analytical expression for the reflection coefficient from the interface between the two biphasic media.Although the angle of incidence is very complex,but for normal incidence,the problem is greatly simplified.Based on the asymptotic model of the two-phase porosity media,the oil-gas identification of the two-phase medium porosity reservoir is carried out.Asymptotic model constructed by formula,expressing the relation between the elastic modulus of the porous medium with the rock matrix,reservoir permeability,the parameters associated with the fluid flow,and the wave equation.Through the equilibrium equation of Hooke ’s law,momentum and mass and the derivation of dynamic Darcy’ s law,some new physical explanations are given to the parameters of some classical porosity theory.And the relationship between the fluid parameter and the seismic wave frequency is expressed by setting the parameter ε.In the progressive analysis,some parameters are decoupled,independent,and some of the associated high order terms are routed to obtain a relatively simple expression of the reflection coefficient and the transmission coeffic ient of the plane wave passing through the interface of the permeable medium formula.Through the expression of the reflection coefficient of fast wave,the objective function is established,and the method of inversion and inversion of the fluid parameter term B is used to simulate the annealing algorithm,and the parameter control and selection of the algorithm are pushed to achieve the global minimum.Get the optimal solution.The stronger the amplitude of the B parameter,the stronger the fluid that the target reservoir has.And then the B parameter is weighted,so that the response of the gas-bearing oil reservoir is more sensitive to the response of the aquifer reservoir,so as to achieve the purpose of fluid identification.