Method for predicting shale nanopore permeability based on fractal theory

A nano-porosity and fractal theory technology, applied in permeability/surface area analysis, analysis materials, measurement devices, etc., can solve problems such as insufficient flow regime, inability to generalize, and pore pressure not considered, to reduce the cost of prediction and calculation. Fast, simple model effects

Active Publication Date: 2019-12-13
SOUTHWEST PETROLEUM UNIV
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Problems solved by technology

However, analyzing previous studies, we still find that these prediction methods have many defects, such as not considering the comprehensive flow regime, shale pore

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  • Method for predicting shale nanopore permeability based on fractal theory
  • Method for predicting shale nanopore permeability based on fractal theory
  • Method for predicting shale nanopore permeability based on fractal theory

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Embodiment Construction

[0065] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0066] A method for predicting the permeability of shale nanopores based on fractal theory, comprising the following steps:

[0067] First, based on the fractal theory and the capillary bundle model, the expressions of the flow section and the length scale represented by the fractal dimension are established, and the expressions of the flow section and the length scale are:

[0068]

[0069]

[0070] In the formula:

[0071] A is the flow cross-sectional area, m 2 ;

[0072] π is pi, dimensionless;

[0073] D. p is the fractal dimension of the pore area, dimensionless;

[0074] D. max is the diameter of the largest capillary bundle pipe, m;

[0075] φ is porosity, dimensionless;

[0076] D. min is the diameter of the minimum capillary bundle pipe, m;

[0077] L is the length scale, m;

[0078] D is the fractal dimension of pore area int...

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Abstract

The invention discloses a fractal theory-based shale nanopore permeability prediction method, which comprises the following steps: establishing an expression of a flow section and a length scale expressed by fractal dimension based on a fractal theory and a capillary bundle model; based on the fractal theory, according to different flow state characteristics in a shale reservoir and the Hastelloy-Poisson's law, establishing a single round pipe gas mass flux integral expression including slip flow, free flow and surface flow; based on the Darcy law, establishing a total expression of the mass flow of the porous medium gas; substituting the mass flux integral expression and the flow section expression into the total expression to obtain a shale nanopore permeability analytical expression considering the multi-scale flow state; and calculating the nano-pore permeability of the shale in different flow states through the shale nanopore permeability analytical expression. According to the method, the permeability of the unconventional reservoir tight shale gas nanopores can be rapidly and accurately predicted.

Description

technical field [0001] The invention relates to the technical field of pore permeability prediction, in particular to a method for predicting shale nano-pore permeability based on fractal theory. Background technique [0002] Shale gas reservoirs have different accumulation methods and reservoir physical properties from conventional gas reservoirs, which lead to the complexity and multi-scale characteristics of shale gas seepage. Therefore, it is necessary to study the gas migration mechanism in different scale pore structures. system analysis. Due to the nanoscale pore size of shale and the coexistence of multiple gas migration mechanisms, it is very challenging to simulate gas flow in shale nanopores. As a result, it is quite difficult to accurately predict the nanopore permeability of unconventional shale reservoirs. However, in the process of oilfield development, the accurate prediction of permeability is of great significance to the accuracy of reserve prediction, re...

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Application Information

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IPC IPC(8): G01N15/08G06F17/50
CPCG01N15/0826
Inventor 王强胡永全赵金洲任岚赵超能赵金
Owner SOUTHWEST PETROLEUM UNIV
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