Method for improving calculation precision of average capillary pressure curve of differential pore separation reservoir

Abstract

The invention provides a method for improving calculation precision of an average capillary pressure curve of a differential pore separation reservoir.. The method comprises the following steps: selecting a plurality of rock core samples from the same kind of reservoirs to carry out capillary pressure experiments; recording a corresponding numerical value of capillary pressure and wetting phase saturation; performing j function dimensionless processing on all capillary pressure curves; recording a corresponding numerical value of the J value and the wetting phase saturation; wherein the fractal J function regression formula 1 and the fractal J function regression formula 2 are respectively used for carrying out multiple nonlinear regression on data; obtaining two groups of regression parameters and a determination coefficient R2; selecting a regression result to be located in a data point range; determining a formula with a coefficient R2 closer to 1 as a basic formula of an average capillary pressure curve of the reservoir; and solving average capillary pressure and wetting phase saturation, namely an average capillary pressure curve, according to a J function definition formula by utilizing the regression parameters, the interfacial tension, the wetting angle and the average porosity and average absolute permeability of the reservoir.

Description

technical field [0001] The invention relates to the field of oil field development, and is an application method for effectively improving the calculation accuracy of the average capillary pressure curve of poor pore sorting reservoirs. Background technique [0002] At present, in the field of oilfield development, the calculation method of the average capillary pressure curve representing the average property of the pore structure of the same type of reservoir is mainly the J function method, which introduces the test capillary pressure curve of a single core sample of the reservoir into Carry out non-dimensionalization, perform power function regression on the J function value and water saturation of multiple cores of the reservoir, and obtain the average capillary pressure curve of the reservoir together with the averaged porosity and absolute permeability of the reservoir. In the theoretical and practical application of this method, there are mainly the following two pr...

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Problems solved by technology

In the theoretical and practical application of this method, there are mainly the following two problems: (1) The measured J function curve of the poorly sorted reservoir does not take the form of an empirical power function, that is, the regression accuracy of the empirical formula is low, and the applicability is limited ; (2) The empirical formula of the J function lacks a theoretical basis, and the regression parameters have no physical meaning

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