Method for calculating gas mass transmission parameters under shale microcrack crack width variation

A technology of transmission parameters and gas quality, applied in the field of mineral resources, can solve the problems such as no relevant research, the calculation method of gas transmission parameters has not been proposed, and the gas quality transmission of shale micro-fractures has a great influence.

Active Publication Date: 2018-07-31
SOUTHWEST PETROLEUM UNIV
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Problems solved by technology

[0007] Since the change of micro-fracture width has a great influence on gas mass transport in shale micro-fractures, previous studies have not done relevant research on the ga

Method used

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  • Method for calculating gas mass transmission parameters under shale microcrack crack width variation
  • Method for calculating gas mass transmission parameters under shale microcrack crack width variation
  • Method for calculating gas mass transmission parameters under shale microcrack crack width variation

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Experimental program
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Embodiment 1

[0272] The basic parameters used in the simulation are shown in Table 1.

[0273] (1) Basic parameters

[0274] Table 1 Simulation basic data table

[0275]

[0276]

[0277] (2) Calculation results

[0278] Depend on figure 2 It can be seen that as the average formation pressure decreases, the fracture width first decreases and then increases, and there is a minimum fracture width when the formation pressure is around 10MPa. Theoretically, there is a maximum fracture width when the formation pressure is close to 0 MPa. When the formation pressure is less than 4MPa or greater than 16MPa, the stress sensitivity increases the fracture width; when the formation pressure is between 4MPa and 16MPa, the stress sensitivity reduces the fracture width. Among them, the compressibility of micro-cracks and the compressibility of matrix both lead to the reduction of fracture width, but gas desorption makes the fracture width larger.

[0279] The apparent permeability is used to...

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Abstract

The invention discloses a method for calculating gas mass transmission parameters under shale microcrack crack width variation. The method comprises the following steps that the reservoir pressure, the microcrack initial size, rock mechanics parameters, and reservoir gas-related parameter basic data are collected; according to the influence of microcrack compressibility, matrix compressibility andgas desorption on the microcrack width, a crack width variation equation under stress sensitivity is established; aiming at different transmission mechanisms, a mass migration equation describing theflow state corresponding to continuous flowing, slippage flowing, Knudsen flowing and the surface diffusion effect under consideration of shale crack width dynamic variation is established; and a unified equation describing mass migration of the different transmission mechanisms under consideration of shale crack width dynamic variation is established. The gas mass transmission parameters in shale microcracks can be calculated, crack width dynamic variation under the stress sensitivity is considered, and the characteristics of novelty, comprehensiveness and the like are achieved.

Description

technical field [0001] The application belongs to the technical field of mineral resources, and in particular relates to a method for calculating gas mass transmission parameters under the change of shale micro-fracture width. Background technique [0002] Under the action of stress and thermal fluid, shale gas reservoirs will produce micro-fractures in the process of diagenesis and hydrocarbon evolution. Regular and irregular micro-fractures are easy to form at the edge of organic matter or weak surfaces. The existence of these micro-fractures has great influence on The mass transport of shale gas has a great influence. According to the definition of Knudsen number, the flow patterns of microfracture gas transport can be divided into continuous flow, slip flow, transitional flow and Knudsen flow. Different flow patterns will also affect the mass transport of shale microfractures. [0003] Compared with sandstone, organic matter in shale is weaker and more easily deformed. ...

Claims

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Application Information

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IPC IPC(8): E21B49/00G06F17/50
CPCE21B49/00G06F30/20G06F2111/10
Inventor 曾凡辉彭凡曾波郭建春向建华
Owner SOUTHWEST PETROLEUM UNIV
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