Method for forecasting pore medium transverse wave velocity which varies with pressure

Abstract

Provided is a method for forecasting a pore medium transverse wave velocity which varies with pressure. The method comprises the steps that measuring coordination numbers are matched and weighed to obtain a coordination number Cp, the coordination number Cp is substituted into a Digby formula considering pressure variation to obtain a Kdry, the coordination number Cp is substituted into a Mindlin formula considering pressure variation to obtain a mudry, and the Kdry and the mudry are substituted into a deformation formula of a Gassmann equation to calculate a forecasted longitudinal wave speed to obtain a weighting coefficient W; the weighting coefficient W is substituted into a formula (2) to obtain the coordination number Cp, after the Cp is obtained, the Cp value is substituted into a formula (8) to obtain the shear modulus mudry of dry rock, then the mudry is substituted into the deformation formula of the Gassmann equation to calculate a forecasted transverse wave speed, a four-dimensional AVO model, an elastic impedance model and the like can be established according to the transverse wave speed which varies with pressure, and therefore the property of oil and gas reservoir with pressure variation on a reservoir stratum in the developing stage can be forecasted. The forecasted transverse wave velocity varying with the pressure can more accord with actual reservoir stratum variation situations.

Description

technical field

[0001] The invention belongs to the field of rock physics in seismic exploration, and in particular relates to a method for predicting shear wave velocity with pressure variation. Background technique

[0002] Through AVO analysis, geophysicists can better evaluate the rock properties of oil and gas reservoirs, including porosity, density, lithology and fluid properties, and shear wave velocity is an indispensable elastic parameter in the process of establishing AVO model and converting wave analysis . In most cases, there is no shear wave velocity logging data in the research area; people usually replace the shear wave velocity with a constant P-wave velocity ratio, but the P-wave velocity ratio should be different for different media, such an assumption is unreasonable. Therefore, many geophysicists are studying the prediction method of shear wave velocity. There are empirical formulas and those based on rock physics theory.

[0003] In 1963, Pickett gav...

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