Method for predicting coal seam hydraulic fracturing permeability

A technology of hydraulic fracturing and prediction method, applied in permeability/surface area analysis, measurement device, suspension and porous material analysis, etc., can solve the problem that coal seam permeability cannot be quantitatively characterized, and achieve the effect of improving pertinence

Active Publication Date: 2018-11-02
XIAN UNIV OF SCI & TECH
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Problems solved by technology

At present, there are few studies on the permeability of coal seams after hydraulic fracturing, and the permeability of coal seams after hydraulic

Method used

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  • Method for predicting coal seam hydraulic fracturing permeability
  • Method for predicting coal seam hydraulic fracturing permeability
  • Method for predicting coal seam hydraulic fracturing permeability

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Embodiment Construction

[0030] Such as figure 1 Shown, a kind of coal seam hydraulic fracturing permeability prediction method of the present invention comprises the following steps:

[0031] (1) Determination of coal seam original permeability k by permeability test 0 ;

[0032] The specific steps of the step (1) are: collecting coal samples from hydraulic fracturing coal seams and drilling coal cores with a coring machine to process them into standard test pieces, placing the test pieces between the upper pressure head and the lower pressure head of the pressure chamber according to the maximum principal stress of the coal seam hydraulic fracturing site (σ 1 ) and minimum principal stress (σ 3 ) size, the corresponding axial pressure (σ 1 ) and confining pressure (σ 3 ), read the fluid flow rate (q) through the flowmeter, and measure the original permeability k of the specimen 0 , k 0 It is obtained by the following calculation formula:

[0033]

[0034] In the formula: k 0 is the origi...

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Abstract

The invention relates to a method for predicting coal seam hydraulic fracturing permeability. The method comprises the following steps: (1) measuring original coal seam permeability k0 through a permeability test; (2) performing fitting on permeability test data in the fracturing process to obtain the permeability change rule k1 in the coal seam hydraulic fracturing process, and performing calculation to obtain the coal seam permeability k10 when hydraulic fracturing is completed; (3) performing fitting on permeability test data in the drainage process to obtain permeability change rule k2 inthe drainage process after coal seam hydraulic fracturing, and performing calculation to obtain the coal seam permeability k20 at the end of drainage; (4) obtaining permeability change rule k in the process of gas extraction after hydraulic fracturing of coal seams by taking account of gas adsorption expansion and pore fluid pressure, and performing calculation to obtain coal seam permeability indifferent gas pressures in the process of gas extraction after hydraulic fracturing. The coal seam permeability after hydraulic fracturing is quantitatively calculated, and the transformation of the coal seam hydraulic fracturing effect from qualitative analysis to quantitative analysis is achieved.

Description

technical field [0001] The invention relates to a coal seam hydraulic fracturing permeability prediction method, which is particularly suitable for the field of low permeability coal seam hydraulic fracturing permeability enhancement engineering. Background technique [0002] Gas is not only the "first killer" of coal mines, but also a non-renewable clean energy. Efficient gas drainage is the main way to control gas disasters and utilize resources. my country's coal seams are affected by multi-stage tectonic history, with complex geological conditions, high gas pressure, high gas content, and low permeability, making gas extraction very difficult. Especially at present, my country has entered the stage of deep well mining, the average mining depth has reached 600m, and it is extending downward at a rate of 20m every year. The increase of mining depth will inevitably increase the difficulty of gas drainage. Therefore, solving the problem of high-efficiency drainage of deep c...

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Application Information

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IPC IPC(8): G01N15/08
CPCG01N15/088
Inventor 徐刚
Owner XIAN UNIV OF SCI & TECH
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