Method for mining coalbed methane through coalbed burning assisted fracture forming

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 the problems of easy sand plugging, difficult construction, reservoir damage, etc. Fracturing fluid contamination and the effect of avoiding compaction

Active Publication Date: 2016-11-09
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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  • Method for mining coalbed methane through coalbed burning assisted fracture forming
  • Method for mining coalbed methane through coalbed burning assisted fracture forming
  • Method for mining coalbed methane through coalbed burning assisted fracture forming

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0052] Example 1. Coalbed methane reservoir combustion reformation

[0053] 1) For selected CBM 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%, almost no gas is produced in the initial test, and nitrogen (N 2 ) (can also inject carbon dioxide (CO 2 )) gas pushes the coalbed methane near the wellbore to a depth of about 5m (equivalent to 25,000m under ground conditions) 3 ), for the purpose of isolating the injected air and the coalbed methane in the later stage, avoiding the risk of explosion caused by the direct contact between the injected air and the 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℃, the maximum temperature is 525℃, and the initial injection speed is about 5000m 3 / d, the ignition time is 4 days, continue to inject air after turning off the igniter, and ...

Embodiment 2

[0059] Example 2. Fracturing + Coalbed Gas Reservoir Fire Combination Reform

[0060] 1) For the selected CBM well, the depth is 606.6-609.6m, the thickness is 3m, and the gas content is 16-20m 3 / t, the gas saturation is 73%-93%. First, high-energy gas fracturing is used to generate multiple fractures.

[0061] 2) Run the electric heating igniter into the bottom of the well, inject air to ignite, the ignition temperature is guaranteed to be above 500℃, the highest temperature is 543℃, 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 generate more micro-cracks, increase the ventilation volume by 20000m in the later stage 3 / d air injection, accumulative air injection 40×10 4 m 3 , ignite the coal seam in the near wellbore area, and finally form the cave completion effect in the near wellbore area, relieve the pollution in the near wellbore area, and improve the seepage capacity in the...

Embodiment 3

[0066] Example 3. Horizontal well in coalbed methane reservoir + combustion reformation

[0067] 1) For the selected CBM horizontal wells, the length of the horizontal well section is 500m 3 , the depth of the 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 a depth of about 5m (equivalent to 60,000m under ground conditions) 3 ), for the purpose of isolating the injected air and the coalbed methane in the later stage, avoiding the risk of explosion caused by the direct contact between the injected air and the coalbed methane.

[0068] 2) Run 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℃, the maximum temperature is 532℃, and the initial injection speed is about 12000m 3 / d, the ign...

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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 coalbed methane development, and in particular relates to a method for exploiting coalbed methane by using fire-burning coal seams to assist fracture-making. 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, partially free in coal pores or dissolved in coal seam water, commonly known as "gas", with methane (CH 4 ), followed by carbon dioxide (CO 2 ), nitrogen (N 2 ), etc., the calorific value is 2 to 5 times that of general coal, and 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 afterward, hardly producing any exhaust gas. In addition to being used as industrial, chemical, power generation and residential fuel energy,...

Claims

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Application Information

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Patent Type & Authority Applications(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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