Flow-state evaluation method capable of considering shale multiscale effect

Abstract

The invention discloses a flow-state evaluation method capable of considering the shale multiscale effect. The method comprises the following steps that S1, a shale core basic parameter is collected;S2, an apparent permeability calculation model capable of considering the multiscale effect is built; S3, four seepage flow models which exist at the same time are built, and a related algorithm is combined to obtain pressure response curves of an upstream chamber and a downstream chamber; S4, a pulse decay method experiment is used for measuring the pressure response curves of the upstream chamber and the downstream chamber; S5, in combination with the shale core pressure response modes of different development conditions, fitting of the experiment data is carried out to obtain the pressure response curves of the upstream chamber and the downstream chamber through calculation, and the shale core parameter is obtained through calculation; and the four seepage flow models which simultaneously exist in the shale core and consider an adsorption and desorption matrix and matrix + natural fracture development are built, the pressure response curves in the upstream chamber and the downstreamchamber are obtained through calculation, the pressure response curves obtained through calculation and the pressure response curves measured through the experiment are subjected to fitting, and related parameters and distributions of four flow states in the shale core can be obtained.

Description

technical field [0001] The invention relates to the field of shale development, in particular to a fluid state evaluation method considering multi-scale effects of shale. Background technique [0002] Due to the shale core and its tightness, the conventional steady-state method, pressure drop method and other core permeability testing methods cannot accurately test the gas flow through the core. Brace introduced the well testing theory into the core test in 1968, and obtained the Pulse decay method for testing ultra-low permeability core permeability. Scholars at home and abroad have conducted a lot of research on this method. The national standard GB / T34533-2017 gives the specific operation steps and methods for testing shale permeability based on the pulse decay method of the Brace matrix core model. However, there are still the following defects and problems. [0003] 1. The Brace model is based on the steady-state flow in matrix shale, and does not consider the unstead...

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Problems solved by technology

[0003] 1. The Brace model is based on the steady-state flow in matrix shale, and does not consider the unsteady flow of gas in the core, the influence of gas adsorption and desorption in the shale, and the impact of natural fractures developed in the shale core. The effect of gas flow

[0004] 2. The Brace model ignores higher-order terms during the solution process, resulting in an approximate solution

[0005] 3. The apparent permeability obtained by the GB / T34533-2017 test method does not consider the influence of multi-scale seepage in shale cores

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