Inversion method of original permeability of gas-water two-phase seepage stress sensitive reservoir

Abstract

The invention relates to an inversion method of the original permeability of a gas-water two-phase seepage stress sensitive reservoir. The method comprises the steps that (1), daily production data ofa gas well, reservoir physical properties, fluid properties, and stress sensitive data are collected and collated; (2), gas-water equivalent permeability curves under different pressure conditions are calculated; (3), improved pseudo parameters taking gas-water two-phase complex seepage characteristics of the stress sensitive reservoir into consideration are calculated; (4), drawing is conductedand an improved semi-logarithmic curve is utilized to identify pseudo radial flow; (5), linear regression is performed on scatters on the curve, and a reservoir original permeability calculation modelis utilized to achieve the inversion of the original permeability according to the slope of a straight line obtained by the regression. According to the method, the complex seepage characteristics such as stress sensitivity of a relative permeability curve, absolute permeability stress sensitivity, a slippage effect and the like can be fully considered, errors caused by a traditional calculationmethod are eliminated, and the method can be extensively applied to reservoir parameter evaluation of the stress sensitivity reservoir.

Description

technical field [0001] The invention relates to the technical field of gas reservoir development, in particular to an original permeability inversion method for a gas-water two-phase seepage stress-sensitive reservoir. Background technique [0002] The permeability of stress-sensitive reservoirs is usually low and changes continuously with the change of formation pressure. Before the development of stress-sensitive gas reservoirs, the formation pressure remains at the original formation pressure, and the permeability at this time is called the original permeability. For stress-sensitive reservoirs with gas-water two-phase seepage, accurate acquisition of original permeability is very important for predicting the change law of reservoir permeability during development, predicting gas well productivity, and formulating a reasonable development plan. [0003] However, some existing original permeability inversion methods do not comprehensively consider the complex seepage char...

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Problems solved by technology

[0003] However, some existing original permeability inversion methods do not comprehensively consider the complex seepage characteristics of gas-water two-phase in stress-sensitive reservoirs, especially ignore the stress sensitivity of phase permeability curves. There is usually a certain difference between the true values, so it is not suitable for the inversion of the original permeability of the gas-water two-phase seepage stress-sensitive reservoir

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