A Bayesian time-shifted avo inversion method and system based on biot theory

Abstract

The invention discloses a Bayesian time shift AVO inversion method and system based on a Biot theory. The method comprises the steps of: (1), on the basis of the Biot theory, constructing the relationship between a seismic record and a reservoir parameter; (2), on the basis of a Bayesian theory, constructing a target function inverted by the reservoir parameter; (3), deducing an inversion equationof the reservoir parameter by using a Gauss-Newton method; (4), deducing a time shift AVO joint inversion equation; and (5), giving an initial model, and performing iterative calculation. According to the Bayesian time shift AVO inversion method and system based on the Biot theory in the invention, the reservoir parameter before time shift and the reservoir parameter change before and after timeshift can be obtained by inversion stably and accurately. The Bayesian time shift AVO inversion method and system based on the Biot theory in the invention has the advantages that: seismic reflectioncharacteristics of a reservoir can be described more accurately by using a longitudinal wave reflection coefficient equation based on the Biot theory; the inversion target function is constructed by using the Bayesian theory; furthermore, low-frequency information is compensated by adding a model constraint item; inversion is relatively steady; linearization of a nonlinear problem is realized by using the Gauss-Newton method; implementation is convenient; and the calculation efficiency is high.

Description

technical field [0001] The invention relates to the field of oil and gas geophysical exploration, and more specifically relates to a Bayesian time-shift AVO inversion method and system based on Biot theory. Background technique [0002] Time-lapse seismic technology is a widely used oil and gas reservoir monitoring and management method. By conducting two or more repeated seismic explorations on the same work area in different periods of oil and gas production, the reservoir can be inferred based on the change of seismic response over time. fluid changes. Time-lapse AVO inversion is an important quantitative interpretation method, which is usually carried out in two steps. Firstly, the change information of elastic parameters (such as velocity, density, impedance, etc.) is obtained based on Zoeppritz equation inversion; Changes estimate reservoir parameter changes (eg, fluid saturation changes, pressure changes, etc.). But the conventional method has two deficiencies. Fir...

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Problems solved by technology

First, the real reservoir is a two-phase medium composed of solid and fluid, and the Zoeppritz equation is obtained on the basis of the assumption of a single-phase solid medium. Using it for time-lapse AVO inversion requires the fluid-bearing reservoir to be equivalent to is a single solid, so the Zoeppritz equation cannot reflect the characteristics of the reflection coefficient of the reservoir very objectively and accurately; second, estimating the change of reservoir parameters through two steps will introduce a certain cumulative error, and it is best not to introduce intermediate variables, directly Inversion of Reservoir Parameter Variations from Time-Lapse Seismic Records

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