Low-permeability deformation medium nonlinear seepage numerical simulation method based on boundary layer

Abstract

The invention provides a low-permeability deformation medium nonlinear seepage numerical simulation method based on a boundary layer. The low-permeability deformation medium nonlinear seepage numerical simulation method comprises the steps: a reservoir nonlinear seepage model based on the boundary layer is built; according to the relation that the reservoir deformation medium permeability is changed with effective stress, a reservoir pressure sensitive model is built by combining with the effective stress coefficient; based on a capillary communicator device, the low-permeability rock core static starting pressure is measured, and the minimum starting pressure gradient of a rock core is obtained; the influences of the boundary layer effect, the pressure sensitivity and the minimum startingpressure gradient are comprehensively considered, and a deformation medium nonlinear seepage mathematical model based on the boundary layer is built; and transforming is conducted based on a traditional black oil numerical simulation software platform, and low-permeability nonlinear seepage numerical simulation is achieved. According to the low-permeability deformation medium nonlinear seepage numerical simulation method based on the boundary layer, depicting for the rock core seepage characteristic is truly and comprehensively reflected, the high reliability and accuracy are achieved, and the effective technical support is provided for adjusting and optimizing of the low-permeability oilfield development scheme.

Description

technical field [0001] The invention relates to the field of reservoir numerical simulation theory research, technical application and oil and gas field development enhanced recovery, in particular to a nonlinear seepage numerical simulation method for low-permeability deformable medium based on boundary layer. Background technique [0002] With the increasingly severe situation of world oil resources, the development of low-permeability reservoirs has become an important part of oil resource output replacement. However, low permeability reservoirs have low permeability, and their seepage characteristics are quite different from those of conventional medium and high permeability reservoirs. The fluid flow does not satisfy Darcy's law, and there are nonlinear seepage characteristics. Throats are easily deformed under pressure changes, which further complicates the seepage capacity of the reservoir, so it is very difficult to perform accurate numerical simulation calculations....

AI Technical Summary

Problems solved by technology

However, low permeability reservoirs have low permeability, and their seepage characteristics are quite different from those of conventional medium and high permeability reservoirs. The fluid flow does not satisfy Darcy's law, and there are nonlinear seepage characteristics. Throats are easily deformed under pressure changes, which further complicates the seepage capacity of the reservoir, so it is very difficult to perform accurate numerical simulation calculations

At present, there are still many controversies and deficiencies in the study of numerical simulation methods for low-permeability reservoirs. There are two mainstream processing methods for nonlinear seepage characteristics. One is the quasi-threshold pressure gradient method commonly used by commercial software. Approximate processing, ignoring the nonlinear seepage section, and using the pseudo-threshold pressure gradient as the threshold value of fluid flow, this method is suitable for general low-permeability reservoirs with short nonlinear seepage sections, and for ultra-low permeability or even tight sandstone reservoirs The linear seepage section is long, and the calculation error is large; the other is to establish a continuous seepage model by means of curve fitting, but the parameters in the continuous seepage model are all fitting parameters, which have no actual physical meaning, and pressure sensitivity is not considered The impact of other characteristics of the reservoir on seepage cannot comprehensively reflect the seepage characteristics of low-permeability reservoirs, and it is difficult to popularize

For the numerical simulation research of low-permeability reservoirs, there is a lack of systematic and effective nonlinear seepage models, which cannot better guide the formulation of development plans and the prediction of development indicators

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