A Multi-Field Coupled Permeability Calculation Method Considering Differences in Shale Matrix

A calculation method and technology of permeability, which is applied in the field of calculation of shale permeability to avoid calculation errors

CN108229048BActive Publication Date: 2021-04-06RES INST OF SHAANXI YANCHANG PETROLEUM GRP
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
Publication Date
2021-04-06

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Abstract

The invention relates to a calculation method of shale permeability. A method for calculating the multi-field coupling permeability considering the difference of shale matrix, characterized in that the described permeability, on the basis of the prior art scheme, further considers the interaction between adsorbed gas and free gas on the shale The influence of rock permeability is considered, and the influence of water film thickness on shale permeability is considered. The influence of the interaction between adsorbed gas and free gas, the influence of water film thickness and the influence of viscous flow, diffusion, thickness of adsorbed layer gas, matrix shrinkage and stress sensitivity are all coupled into the shale permeability calculation model. The impact of various properties of shale on permeability can be more comprehensively characterized. Based on the respective characteristics of shale organic matter and inorganic matter, the calculation models of organic matter and inorganic matter permeability were established respectively. Calculation errors caused by matrix differences can be effectively avoided.
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Description

technical field

[0001] The invention relates to a calculation method of shale permeability. Background technique

[0002] Shale permeability is a key parameter to guide shale gas productivity evaluation and shale gas development. There are generally experimental methods and calculation methods to obtain shale permeability. The experimental method can obtain relatively accurate results, but the cost is too high. At present, there are endless calculation methods for shale permeability. For example, the calculation method of shale matrix permeability proposed by Mi Lidong corrects the slippage coefficient, which represents slippage and free gas diffusion. Shale permeability calculation model of joint influence. Wang Rui characterized the effect of the adsorption layer on the shale pore size, and established a shale permeability calculation model considering the effects of adsorption, slippage and diffusion. Cao Cheng proposed a shale permeability calculation model considering...

Examples

Embodiment Construction

[0067] 1. Establishment of calculation model for organic matter permeability

[0068] There are free gas and adsorbed gas in the pores of organic matter, but the transmission modes of the two are very different. Adsorbed gas will have a certain impact on the pore size, porosity and free gas transmission of organic matter, so it will affect the permeability of organic matter. In the micro-nano-level pore size, gas diffusion will also have a certain impact on the permeability of organic matter.

[0069] Under the control of the micro-nano-scale pore structure, free gas is mainly transported through viscous flow and diffusion flow under the action of pressure or concentration difference.

[0070] 1) Viscous streaming

[0071] Assuming that the gas is transported in a viscous laminar flow in a capillary with radius r, the transport velocity at any radius ξ is

[0072]

[0073] In the formula, v is the gas transmission velocity, m / s; r is the capillary radius, m; μ g is the g...