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Field test method for gas starting pressure gradient and permeability of low-permeability coal reservoir

A start-up pressure gradient, on-site testing technology, applied in the direction of permeability/surface area analysis, measuring device, suspension and porous material analysis, etc., can solve the problem that the permeability cannot accurately reflect the actual situation on site, and achieve theoretically accurate results

Inactive Publication Date: 2016-11-16
HENAN POLYTECHNIC UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Therefore, the laboratory test start-up pressure gradient method has its limitations, and the obtained permeability often cannot accurately reflect the actual situation on site.

Method used

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  • Field test method for gas starting pressure gradient and permeability of low-permeability coal reservoir
  • Field test method for gas starting pressure gradient and permeability of low-permeability coal reservoir
  • Field test method for gas starting pressure gradient and permeability of low-permeability coal reservoir

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Embodiment 1

[0038] Such as figure 1 As shown, the present invention provides a field test method for gas start-up pressure gradient and permeability of low-permeability coal reservoirs, which specifically includes the following steps:

[0039]The first step: select a representative blank area in the low-permeability coal reservoir 1 in the coal mine, the blank area refers to the complete low-permeability coal reservoir 1 that has not been damaged by mining, and there are no other drilled areas within 10 meters around it. borehole interference, a piercing borehole is constructed through the coal seam floor 2 in the blank area as a pressure-measurement borehole, and the pressure-measurement borehole is recorded as C 1 , piezometric borehole C 1 The hole diameter is 94 mm, piezometric borehole C 1 Inner enclosure and pressure measurement drilling C 1 Four-part aluminum-plastic pipe 3 of equal depth and equal length, located in the pressure measurement borehole C 1 The inner four-point al...

Embodiment 2

[0060] The on-site test method for the start-up pressure gradient and permeability of low-permeability coal reservoir gas after hydraulic punching includes the following steps:

[0061] The steps of this embodiment two are basically the same as those of the example one, and will not be repeated one by one. The difference is that in the second step of the example one, the gas drainage drilling C 2 After the drilling construction is completed, the gas drainage drilling C 2 Carry out hydraulic punching, and drill holes for gas drainage after the hydraulic punching is completed 2 Perform gas extraction. Among them, the amount of coal produced by hydraulic punching is based on the gas drainage drilling C 2 See that the length of the coal section is not less than 1t / m.

[0062] With gas drainage drilling C 2 Continuous gas extraction, gas drainage drilling C 2 Nevas velocity v and piezometric borehole C 1 The reading of the pressure gauge will continue to decrease, and the inl...

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Abstract

The invention relates to a method for on-site testing of the start-up pressure gradient and permeability of gas in low-permeability coal reservoirs. By selecting representative blank areas in the low-permeability coal reservoirs in coal mines, drilling holes for pressure measurement and gas drainage holes are constructed. , and seal the pressure measurement borehole and the gas drainage hole respectively, observe and record the pressure gauge readings of the pressure measurement borehole and the gas flow readings of the gas drainage hole, and use the gas seepage equation and the starting pressure gradient formula to derive The permeability of the coal reservoir. This method does not need to process coal samples, and the particle size, moisture content, homogeneity, and confining pressure of the coal body are all characteristics of the coal reservoir in the real state. The permeability of the coal reservoir calculated by long-term field observation The average value is more accurate and can be used as a reference value for the coal reservoir permeability of the low-permeability coal seam in the entire mine. At the same time, this method provides a theoretically accurate and feasible method for testing the gas start-up pressure gradient and permeability of low-permeability coal reservoirs. new ideas.

Description

technical field [0001] The invention relates to the field of starting pressure gradient and permeability testing, in particular to a field-based testing method for starting pressure gradient and permeability of gas in low-permeability coal reservoirs. Background technique [0002] The concept of threshold pressure gradient has been proposed for more than 60 years. It means that when the fluid flows in the reservoir, the pressure gradient of the fluid must be greater than a certain critical value before the flow can occur. This critical value is the threshold pressure gradient. Later scholars found that there is also a critical value for gas flow in low-permeability coal reservoirs, and this critical value is the starting pressure gradient of coal reservoir gas. The vast majority of coal reservoirs in my country have the characteristics of "high storage and low permeability", which seriously restricts the rapid development of my country's coal mine gas drainage and coalbed me...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N15/08
CPCG01N15/0826G01N15/08
Inventor 苏现波李贤忠宋金星冯俊超郭红玉王乾
Owner HENAN POLYTECHNIC UNIV
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