Drilling fluid for protecting coal bed against collapse

A drilling fluid and coal seam technology, applied in the field of coalbed methane exploration, can solve the problems of large economic losses, damage to coal seams, buried drilling tools, etc., and achieve the effects of small damage, reduced complex accidents, and high-efficiency mining

Active Publication Date: 2013-08-14
BC P INC CHINA NAT PETROLEUM CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0002] In order to better protect coalbed methane resources, clean water aeration and underbalanced methods are generally used to drill multi-branch horizontal wells in China. However, due to technical and geological factors, accidents such as well collapse and buried drilling tools occur from time to time, resulting in huge economic losses.
Although the traditional mud technology can solve the problem of wellbore instability, it seriously damages the coal seam. Coal seam protection and wellbore stability have become the main contradiction in the safety drilling technology of coal seam horizontal wells, multi-branch horizontal wells and U-shaped wells.

Method used

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  • Drilling fluid for protecting coal bed against collapse
  • Drilling fluid for protecting coal bed against collapse
  • Drilling fluid for protecting coal bed against collapse

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0020] A drilling fluid for protecting coal seams from collapsing is made of the following components by weight percentage:

[0021]

[0022] The degradation desorbent used is a mixture of ammonium persulfate and sodium hypochlorite solution, and the weight percentage composition of the two is 60% and 40% respectively.

[0023] Weigh each component according to the above ratio, and mix thoroughly to obtain a density of 1.03g / cm 3 The performance index of the drilling fluid is shown in the table below:

[0024]

Embodiment 2

[0026] A drilling fluid for protecting coal seams from collapsing is made of the following components by weight percentage:

[0027]

[0028] Wherein the weight percent composition of fluid loss reducer is as follows:

[0029] Sodium Carboxymethyl Cellulose 90%

[0030] Polyanionic Cellulose 10%.

[0031] The degradation desorbent is a mixture of ammonium persulfate and sodium hypochlorite solution, and the weight percentage composition of the two is 90% and 10% respectively.

[0032] Weigh each component according to the above ratio, and mix thoroughly to obtain a density of 1.03g / cm 3 drilling fluid. The performance index of the drilling fluid is shown in the table below:

[0033]

Embodiment 3

[0035] A drilling fluid for protecting coal seams from collapsing is made of the following components by weight percentage:

[0036]

[0037] Wherein the weight percent composition of fluid loss reducer is as follows:

[0038] Sodium Carboxymethyl Cellulose 85%

[0039] Polyanionic Cellulose 15%

[0040] The degradation desorbent is a mixed solution of ammonium persulfate and sodium hypochlorite solution, and the composition of the two is 70% and 30% by weight respectively.

[0041] After mixing the above raw materials, the density is 1.02g / cm 3 The performance index of the drilling fluid is shown in the table below:

[0042]

[0043] In the above examples, density, apparent viscosity, plastic viscosity, initial shear, final shear and dynamic shear force are conventional performance indicators of drilling fluid. By adjusting the formula of the drilling fluid, drilling fluids with different densities can be obtained, which can effectively reduce leakage an...

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Abstract

The invention discloses drilling fluid for protecting a coal bed against collapse. The drilling fluid is prepared from the following components in percentage by weight: 1-2% of clay stabilizer, 0.2-0.5% of viscosity increaser, 0-0.8% of filtrate loss reducer, 0.01-0.5% of degradation desorbent, 0.3-1.2% of pH value regulator and the balance of water. The density, viscosity and degradation time of the drilling fluid can be regulated by adjusting the formula, and the system has no solid phase, no clay and small damage to the coal bed; and the drilling fluid shows good capacity of bringing debris during the drilling process, can promote the stability of a well wall, reduce the occurrence of underground complex accidents and meet the high-efficient mining requirements of coal bed gas, and is suitable for well completion operation of coal bed drilling of horizontal wells, multi-branch horizontal wells and U-shaped wells.

Description

technical field [0001] The invention relates to the field of coal bed gas exploration, in particular to a drilling fluid which protects coal seams and has the function of preventing collapse. Background technique [0002] In order to better protect coalbed methane resources, clean water and aerated underbalanced methods are generally used to drill multi-branch horizontal wells in China. However, due to technical and geological factors, accidents such as well collapse and buried drilling tools occur from time to time, resulting in huge economic losses. Although the traditional mud technology can solve the problem of wellbore instability, it seriously damages the coal seam. Coal seam protection and wellbore stability have become the main contradiction in the safety drilling technology of coal seam horizontal wells, multi-branch horizontal wells and U-shaped wells. Contents of the invention [0003] The purpose of the present invention is to overcome the shortcomings of the a...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C09K8/10C09K8/035
Inventor 刘大伟虞海法王益山袁孟雷贾东民代礼杨刘艳艳苏秀纯田野赵福祥李洪俊郭贤伟
Owner BC P INC CHINA NAT PETROLEUM CORP
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