METHOD FOR DYNAMIC WATER FEEDING AND HOLE SEALING USING HIGH WATER-ABSORBENT RESIN

Abstract

A method for dynamic water feeding and hole sealing using high water-absorbent resin is applicable to sealing of a borehole on which extraction has a great impact. Two ends of a hole-sealed section of the borehole are sealed. Fine mixed high water-absorbent resin powder wrapped in a piece of cotton cloth is disposed in the hole-sealed section of the borehole, a water injection pipe and a gas extraction pipe are inserted in the borehole, and an automatic feed water valve is used to inject water into the hole-sealed section. The fine mixed high water-absorbent resin powder that fills the hole-sealed section and surrounding cracks with the water flow rapidly swells up after soaking up water to fill the hole-sealed section, and maintains at a swelling pressure. After the powder swells up and hole sealing is completed, the extraction pipe is connected to an extraction apparatus to perform gas extraction. This method has advantages such as tight hole sealing, high automation degree, and dynamic hole sealing, thus effectively solving problems that pores around the borehole are poorly sealed, it is difficult to seal cracks newly produced by extraction and so on. Moreover, the powder for hole sealing is low in price, and therefore the hole sealing cost is low.

Claims

1. A method for dynamic water feeding and hole sealing using high water-absorbent resin, comprising the following steps: a. winding a polyurethane material tape A (3) for sealing a borehole (2) around a front end of a drainage pipe (8); b. wrapping fine mixed high water-absorbent resin powder in a piece of cotton cloth, and winding the cotton cloth strip (6) in which the fine mixed high water-absorbent resin powder is wrapped around a portion of the drainage pipe (8) behind the polyurethane material tape A (3); c. winding a polyurethane material tape B (7) for sealing the borehole (2) around a portion of the drainage pipe (8) behind the cotton cloth strip (6) in which the fine mixed high water-absorbent resin powder is wrapped, and simultaneously winding the polyurethane material tape B around a water inlet section of a water injection pipe (9), such that an inlet end of the water injection pipe (9) is located between the polyurethane material tape A (3) and the polyurethane material tape B (7); rapidly inserting the drainage pipe (8) to a specified position in the borehole (2); and forming a hole-sealed section (4) after the polyurethane foams and solidifies; d. mounting an automatic feed water valve (10) on the water injection pipe (9) and setting a pressure, and connecting the valve to a downhole water-supply pipe (11); e. turning on the automatic feed water valve (10) to start injecting water into the formed hole-sealed section (4) at the set pressure; f. unfolding the cotton cloth by the fine mixed high water-absorbent resin powder in the cotton cloth wound around the drainage pipe (8) under the effect of water, such that the powder comes into the hole-sealed section and enters cracks (5) with the water flow to fully seal the cracks and isolate gas leakage channels; the fine mixed high water-absorbent resin powder rapidly swells up after soaking up water to fill the hole-sealed section, and tightly presses against the cracks around the borehole under its swelling pressure; g. automatically stopping water injection when the water injection pressure reaches a set value; h. connecting the drainage pipe (8) to an extraction pipe network according to conventional techniques, to perform gas extraction; and i. when the water injection pressure approaches zero, automatically starting water feeding by using the automatic feed water valve (10), such that the fine high water-absorbent resin powder maintains a water-swelling state, thus achieving a desirable hole sealing effect.

2. The method for dynamic water feeding and hole sealing using high water-absorbent resin according to claim 1, wherein the high water-absorbent resin powder is formed by a mixture of high water-absorbent resin powder of the following five types: H30-60, H700, H30-50, H100 and H610, the granularity of the high water-absorbent resin powder ranges from 30 meshes to 100 meshes, and the water absorbency thereof ranges from 200 to 700 times.

3. The method for dynamic water feeding and hole sealing using high water-absorbent resin according to claim 1, wherein the pressure of the automatic feed water valve (10) is set according to the length of the hole-sealed section (4) and a cracking degree of the borehole at the scene of a coal mine.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] FIG. 1 is a schematic diagram of hole sealing before water injection according to the present invention; and

[0018] FIG. 2 is a schematic diagram of automatic water feeding after hole sealing according to the present invention.

[0019] In the accompanying drawings: 1. Coal seam, 2. Borehole, 3. Polyurethane material tape A, 4. Hole-sealed section, 5. Cracks, 6. Cotton cloth strip, 7. Polyurethane material tape B, 8. Gas extraction pipe, 9. Water injection pipe, 10. Automatic feed water valve, 11. Downhole water-supply pipeline, and 12. Water-swelling mixed high water-absorbent resin powder.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0020] An embodiment of the present invention is further described below with reference to the accompanying drawings.

[0021] A method for dynamic water feeding and hole sealing using high water-absorbent resin of the present invention specifically includes the following steps:

[0022] a. winding a polyurethane material tape A 3 for sealing a borehole 2 around a front end of a drainage pipe 8, where a portion of a sufficient length is left in front of the polyurethane material tape A 3, and the length is determined according to the actual situation of the borehole 2;

[0023] b. wrapping fine mixed high water-absorbent resin powder in a piece of cotton cloth, and winding the cotton cloth strip 6 in which the fine mixed high water-absorbent resin powder is wrapped around a portion of the drainage pipe 8 behind the polyurethane material tape A 3, where the cotton cloth is folded in half twice to wrap the powder and then spirally wound around the drainage pipe 8, two ends of the cotton cloth being tucked into the middle part thereof to avoid leakage of the powder; the high water-absorbent resin powder is formed by a mixture of high water-absorbent resin powder of the following five types: H30-60, H700, H30-50, H100 and H610, the granularity of the high water-absorbent resin powder ranges from 30 meshes to 100 meshes, and the water absorbency thereof ranges from 200 to 700 times;

[0024] c. spirally winding a polyurethane material tape B 7 for sealing the borehole 2 around a portion of the drainage pipe 8 behind the cotton cloth strip 6 in which the fine mixed high water-absorbent resin powder is wrapped, and simultaneously winding the polyurethane material tape B around a water inlet section of a water injection pipe 9, such that an inlet end of the water injection pipe 9 is located between the polyurethane material tape A 3 and the polyurethane material tape B 7, the distance between the polyurethane material tape A 3 and the polyurethane material tape B 7 being determined according to a state-stipulated standard length of a hole-sealed section; rapidly inserting the drainage pipe 8 to a specified position in the borehole 2; and forming a hole-sealed section 4 after the polyurethane foams and solidifies;

[0025] d. mounting an automatic feed water valve 10 on the water injection pipe 9 and setting a pressure, and connecting the valve to a downhole water-supply pipe 11;

[0026] e. turning on the automatic feed water valve 10 to start injecting water into the formed hole-sealed section 4 at the set pressure;

[0027] f. unfolding the cotton cloth by the fine mixed high water-absorbent resin powder in the cotton cloth wound around the drainage pipe 8 under the effect of water, such that the powder comes into the hole-sealed section and enters cracks 5 with the water flow to fully seal the cracks and isolate gas leakage channels; the fine mixed high water-absorbent resin powder rapidly swells up after soaking up water to fill the hole-sealed section, and tightly presses against the cracks around the borehole under the swelling pressure of the water-swelling mixed high water-absorbent resin powder 12;

[0028] g. automatically stopping water injection by the automatic feed water valve 10 when the water injection pressure reaches a set value;

[0029] h. connecting the drainage pipe 8 to an extraction pipe network according to conventional techniques, to perform gas extraction;

[0030] i. when the water injection pressure approaches zero, automatically starting water feeding by using the automatic feed water valve 10, such that the fine high water-absorbent resin powder maintains a water-swelling state, thus achieving a desirable hole sealing effect.

[0031] The pressure of the automatic feed water valve 10 is set according to the length of the hole-sealed section 4 and a cracking degree of the borehole at the scene of a coal mine, thereby achieving a desirable hole sealing effect. The pressure of the water injection pipe 9 is set according to measurement data. The pressure of the water injection pipe 9 and that of the hole-sealed section 4 are stabilized at set values in spite of the water pressure in the downhole water-supply pipe 11, thereby achieving an automatic water feeding effect.