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A method for exploiting coalbed methane by using burning coal seam to assist fracture making

A technology for coalbed methane and coalbed methane wells, which is applied in the fields of fluid production, earthwork drilling, wellbore/well components, etc., can solve problems such as sand plugging, fracturing fluid filtration, and difficulty in construction, and avoid compaction. effect, improve the effect of reconstruction, no effect of fracturing fluid pollution

Active Publication Date: 2018-08-31
BEIJING PUXIN PETROLEUM TECH DEV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] Due to the differences between the coal seam and other strata, the fracturing operation will be different from the general construction. The main manifestations are as follows: (1) The micro-cracks and cleats in the coal seam are well developed, the fracturing fluid has serious filtration loss, and sand plugging is easy to occur, so the construction High difficulty
(2) The fractures produced by coal seam well fracturing are more complex than expected, and there may be combined fractures composed of horizontal fractures and vertical fractures, that is, T-shaped fractures, which bring difficulties to construction
(3) The fracturing fluid has serious damage to the reservoir
[0007] In summary, the existing coal seam fracturing technology will inevitably cause damage to the reservoir during the implementation process, which will affect the effect of the stimulation. Further research and improvement of related technologies are necessary to overcome the problems exposed during fracturing construction.

Method used

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  • A method for exploiting coalbed methane by using burning coal seam to assist fracture making
  • A method for exploiting coalbed methane by using burning coal seam to assist fracture making
  • A method for exploiting coalbed methane by using burning coal seam to assist fracture making

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0052] Example 1. Coalbed methane reservoir fire reformation

[0053] 1) For selected coalbed methane wells, the depth is 1128.4-1136.8m, the thickness is 5.6m, and the gas content is 15.31-19.36m 3 / t, the gas saturation is 71-89%, the initial test gas hardly produces gas, first inject nitrogen (N 2 ) (can also inject carbon dioxide (CO 2 )) The gas pushes the coalbed methane near the wellbore to about 5m deep in the formation (equivalent to 25000m under ground conditions 3 ), to achieve the purpose of isolation between air injection and coalbed methane in the later stage, and to avoid the risk of explosion caused by direct contact between air injection and coalbed methane.

[0054] 2) Lower the electric heating igniter into the bottom of the well, inject air to ignite, the ignition temperature is guaranteed to be above 500°C, the highest temperature is 525°C, and the initial injection speed is about 5000m 3 / d, the ignition time is 4 days, continue to inject air after tur...

Embodiment 2

[0059] Example 2. Combination reconstruction of fracturing + coalbed methane reservoir fire

[0060] 1) For selected coalbed methane wells, the depth is 606.6-609.6m, the thickness is 3m, and the gas content is 16-20m 3 / t, with a gas saturation of 73%-93%, first use high-energy gas fracturing to generate multiple fractures.

[0061] 2) Lower the electric heating igniter into the bottom of the well, inject air to ignite, the ignition temperature is guaranteed to be above 500°C, the highest temperature is 543°C, and the initial injection speed is about 8000m 3 / d, the ignition time is 5 days, turn off the igniter, continue to inject air, in order to produce more micro cracks, increase the ventilation rate to 20000m in the later stage 3 / d inject air, accumulatively inject air 40×10 4 m 3 , ignite the coal seam near the wellbore, and finally form the completion effect of caves near the wellbore, remove the pollution near the wellbore, and improve the seepage capacity of the n...

Embodiment 3

[0066] Example 3: Coalbed methane reservoir horizontal well + fire reconstruction

[0067] 1) For the selected CBM horizontal well, the length of the horizontal well section is 500m 3 , the depth of coalbed methane reservoir is 514.2-520.6m, the thickness is 5.4m, and the gas content is 16-26m 3 / t, gas saturation 90-98.9%, first inject a certain amount of nitrogen (N 2 ) gas pushes the coalbed methane near the wellbore to about 5m deep in the formation (equivalent to 60000m under ground conditions 3 ), to achieve the purpose of isolation between air injection and coalbed methane in the later stage, and to avoid the risk of explosion caused by direct contact between air injection and coalbed methane.

[0068] 2) Lower the electric heating igniter into the bottom of the well, inject air to ignite, the ignition time is 40 days, the ignition temperature is guaranteed to be above 500°C, the highest temperature is 532°C, and the initial injection speed is about 12000m 3 / d, the ...

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Abstract

The invention discloses a method for mining coalbed methane through coalbed burning assisted fracture forming. The method comprises steps as follows: (1) nitrogen gas and / or carbon dioxide gas are / is injected into a coalbed methane well, near-wellbore area coalbed methane is pushed to a deep position of a stratum by 3-5 m; (2) ignition is performed: air is injected for ignition at the temperature being 500 DEG C or above, and a near-wellbore area coalbed is ignited; (3) air injection is stopped, and the well is closed for 4-5 days; (4) the nitrogen gas or the carbon dioxide gas is injected to dilute involved oxygen in a near-wellbore area, and the mined gas explosion risk is avoided; (5) the coalbed methane is mined normally. The method is suitable for coalbed methane transformation, the cave completion effect in the near-wellbore area can be realized, fissures can be formed with the method instead of through fracturing, and a new thought is provided for effectively improving seepage capability of the coalbed methane.

Description

technical field [0001] The invention belongs to the technical field of coal-bed methane development, and in particular relates to a method for exploiting coal-bed methane by using burning coal seams to assist seam creation. Background technique [0002] Coalbed methane is a hydrocarbon gas stored in coal seams with methane as the main component, mainly adsorbed on the surface of coal matrix particles, and partly free in coal pores or dissolved in coal seam water, commonly known as "gas". 4 ), followed by carbon dioxide (CO 2 ), nitrogen (N 2 ), etc., the calorific value is 2 to 5 times that of general-purpose coal. The calorific value of 1 cubic meter of pure coalbed methane is equivalent to 1.13kg of gasoline and 1.21kg of standard coal, and its calorific value is equivalent to that of natural gas. It is very clean and hardly produces any exhaust gas. In addition to being used as fuel energy for industry, chemical industry, power generation and residential life, coal bed...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): E21B43/247E21B43/16
CPCE21B43/006E21B43/164E21B43/168E21B43/247
Inventor 雷春娣梁金中王普春郭俊
Owner BEIJING PUXIN PETROLEUM TECH DEV
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