Accurate Zeoppritz equation seismic amplitude inversion method and system based on saturated medium

Abstract

The invention provides an accurate Zeoppritz equation seismic amplitude inversion method based on a saturated medium. According to the scheme, firstly, saturated seismic wave velocity containing fluid parameters is introduced into an elastic medium Zoeppritz equation to represent an isotropic saturated medium; then, by means of the perturbation theory and the Taylor expansion method, the problem of solving the target function is converted into the problem of solving the gradient or partial derivative of the reflection coefficient to the model parameters; an iterative least square algorithm and a Bayesian theory are combined, a model parameter iterative update expression is established, a multi-wave saturated medium fluid factor nonlinear direct inversion method based on an accurate Zoeppritz equation is provided, and finally quantitative characterization and accurate prediction containing fluid characteristics and distribution rules are achieved.

Description

technical field [0001] The disclosure belongs to the technical field of conventional or unconventional oil and gas reservoir exploration seismic and fluid prediction, and in particular relates to a seismic amplitude inversion method and system based on an accurate Zeoppritz equation in a saturated medium. Background technique [0002] The statements in this section merely provide background information related to the present disclosure and do not necessarily constitute prior art. [0003] Seismic amplitude inversion is an effective method to obtain internal images of subsurface media and describe reservoirs in detail, and it is also the final form of high-resolution seismic exploration. Seismic data inversion greatly improves the value of reservoir characterization. As the focus of seismic research has gradually shifted from exploration to development, and from conventional oil and gas to unconventional oil and gas, especially shale gas, the fine distribution characteristics...

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Problems solved by technology

[0004] The inventors found that the linear inversion method based on the approximate Zoeppritz equation can stably solve ill-conditioned inversion problems or local extremum problems. large error, failed to make full use of the rich pre-stack information, and could not meet the fine characterization requirements of actual reservoirs in terms of inversion accuracy, especially for actual 3D large offset seismic data

For isotropic saturated media, the traditional approximate reflection coefficient based on the Zoeppritz equation is an expression that includes elastic parameters and fluid characteristic items, but the elastic parameters or fluid characteristic items obtained by conventional inversion are difficult to directly evaluate the reservoir fluid distribution characteristics Characterization, step-by-step inversion, or indirect calculations introduce cumulative errors

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