Method for preventing and controlling coal, rock and gas composite disasters based on drilling holes in coal seam

Abstract

The invention relates to the field of coal rock gas composite disaster prevention and control, in particular to a coal rock gas composite disaster prevention and control method based on coal seam drilling, which comprises the following steps: judging a composite disaster dangerous area; bedding drilling is carried out on the coal seam needing gas extraction and rock burst disaster prevention and control; the drill bit retreats after construction to the designed depth; dividing the drill hole into a rock burst pressure relief drill hole and a gas drainage drill hole along the hole length; sealing the gas drainage hole at the junction of the pressure relief drill hole and the gas drainage drill hole; a gas drainage pump is connected for gas drainage; and the gas extraction pipe of the pressure relief section is coated with a film bag, the gas extraction capacity is enhanced, and the pressure relief effect is calculated. The drilled hole constructed through the method achieves multiple purposes through partitioning, and gas and rock burst disasters are jointly prevented and controlled.

Description

Technical Field

[0001] The invention relates to the field of prevention and control of coal and gas composite disasters, and in particular to a method for preventing and controlling coal-rock gas composite disasters based on coal seam drilling. Background Art

[0002] As the intensity and depth of coal mining continue to increase, the mines face the "three highs and one disturbance" and complex geological conditions after entering deep mining, and rock burst and coal and gas outburst compound dynamic disasters begin to appear frequently. At present, the mechanism, evaluation system, and prevention and control measures for rock burst and coal and gas outburst single disasters are becoming increasingly complete. There is no unified conclusion on the causative factors, occurrence mechanism, coupling relationship, and other issues of coal-rock gas compound dynamic disasters.

[0003] In view of this, the present invention proposes a method for preventing and controlling coal-rock gas composite disasters based on coal seam drilling, which solves the above-mentioned technical problems. Summary of the invention

[0004] The purpose of this section is to summarize some aspects of embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the specification abstract and the invention title of this application to avoid blurring the purpose of this section, the specification abstract and the invention title, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0005] The present invention proposes a method for preventing and controlling coal-rock gas composite disasters based on the coal seam drilling: the method combines the pressure relief drilling hole and the gas extraction drilling hole into one, and through one drilling hole, both coal body pressure relief and gas extraction can be performed, thus realizing "one hole for multiple uses", reducing the cost of disaster prevention and control and alleviating the labor burden.

[0006] A method for preventing and controlling coal-rock gas compound disasters based on the coal seam drilling method includes the following steps: S1: Determine the complex disaster hazard area based on rock burst, gas disaster risk assessment and actual monitoring data of the mine and other influencing factors, and clarify the drilling construction parameters; S2: Drill holes in the coal seam according to the complex disaster risk area determined in S1, and cover the gas extraction pipe with water film in the pressure relief section; S3: When the drilling construction in the composite disaster hazard area is completed, move to the next hazard area until all the divided coal-rock gas composite disaster hazard areas are covered, and the prevention and control project is completed; Preferably, the influencing factors for evaluating the composite disaster risk area in S1 are: Factors affecting gas disasters include: coal seam thickness, coal seam inclination, coal solidity coefficient, roof and floor lithology, gas pressure, coal seam gas content, initial velocity of gas outflow from drilling holes, and gas desorption index of drill cuttings; The factors affecting rock burst disasters include: multi-factor coupling method, comprehensive index method and factors mentioned in impact tendency identification.

[0007] Preferably, the drilling construction parameters in S1 include: borehole diameter, hole spacing, total drilling construction length, pressure relief section length, gas extraction section length, and sealing length.

[0008] Preferably, the drilling construction parameters in S1 are clear, and the drilling hole diameter parameters are determined by the effective influence radius of the drilling. The compressive strength of the coal body, the distribution of cracks inside the coal body, and the stress concentration in the coal body all affect the effective radius of the drilling.

[0009] Preferably, S2 covers the gas extraction pipe in the pressure relief section with a water film. The purpose of borehole pressure relief is to break and collapse the coal body around the hole under the action of stress, expand the cracks and release the stress. However, it is difficult to evaluate whether the collapse inside the borehole is sufficient. After the gas extraction pipe in the pressure relief section is covered with a film bag, liquid is flushed into the film bag. When collapse occurs, the liquid is discharged from the coal wall at the side of the roadway through the drainage pipe. Due to the incompressibility of the liquid, the collapsed area in the hole can be calculated, and the film bag can seal the voids in the gas extraction pipe in the pressure relief section to enhance the gas extraction effect.

[0010] Preferably, the formula for calculating the percentage of collapsed holes is:

[0011] Where: V is the liquid outflow volume monitored by the flow meter, in cm 3 ; R is the diameter of the film, in cm; L is the length of the pressure relief section, in cm; b is the thickness of the film, in cm.

[0012] Preferably, in S3, after constructing a pressure relief and extraction integrated borehole in the complex disaster risk area, the elastic energy accumulated inside the coal body on the coal wall side is released, the high stress is transferred to a deeper level, and the gas contained in the coal body is extracted, the gas concentration and gas pressure are reduced, thereby achieving the joint prevention and control of rock burst disasters and gas disasters.

[0013] Beneficial effects of the present invention: This invention combines the prevention and control concepts of rock burst disasters and gas disasters, and proposes a method for preventing and controlling coal-rock gas composite disasters based on coal seam drilling. This method combines the pressure relief drilling hole and the gas extraction drilling hole into one, and one drilling hole can be used to both meet the needs of coal body pressure relief and gas extraction, realizing "one hole for multiple uses". The pressure relief effect of the pressure relief section can be evaluated by the water discharge of the membrane bag, and the voids in the extraction pipe of the pressure relief section can be sealed to enhance the gas extraction effect, reduce the cost of disaster prevention and control, and alleviate the labor burden. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative labor.

[0015] in: Figure 1 This is a schematic diagram of drilling holes for preventing and controlling coal-rock gas compound disasters according to the present invention; Figure 2 The film bag of the present invention; Figure 3 The schematic diagram of the membrane bag for the coal body pressure relief and gas extraction technology of the present invention; Figure 4 This is a plan view of the drilling arrangement of the present invention.

[0016] In the figure: 1-1—pressure relief and extraction integrated drilling pressure relief section; 1-2—pressure relief and extraction integrated drilling gas extraction section; 1-3—gas guide pipe; 1-4—grouting pipe; 1-5—bag; 1-6—bursting valve; 1-7—gas extraction screen; 2-1—membrane bag on the screen surface; 2-2—flow meter; 3-1—coal body stress curve after pressure relief; 3-2—gas migration path. DETAILED DESCRIPTION

[0017] In order to make the purpose, features and advantages of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described below are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] The present invention provides a method for preventing and controlling coal-rock gas compound disasters based on coal seam drilling. The method comprises the following steps: S1: Determine the complex disaster hazard area based on rock burst, gas disaster risk assessment and actual monitoring data of the mine and other influencing factors, and clarify the drilling construction parameters; S2: Carry out drilling construction in this coal seam according to the complex disaster risk area determined in S1; S3: When the drilling construction in this composite disaster hazard area is completed, move to the next hazard area until all the designated coal-rock gas composite disaster hazard areas are covered and the prevention and control project is completed.

[0019] Specifically, the factors affecting the evaluation of compound disaster risk areas are: Factors affecting gas disasters include: coal seam thickness, coal seam inclination, coal solidity coefficient, roof and floor lithology, gas pressure, coal seam gas content, initial velocity of gas outflow from drilling holes, and gas desorption index of drill cuttings; The factors affecting rock burst disasters include: multi-factor coupling method, comprehensive index method and factors mentioned in impact tendency identification.

[0020] Specifically, the drilling construction parameters in S1 include: borehole diameter, spacing between holes, total drilling construction length, pressure relief section length, gas extraction section length, and sealing hole length.

[0021] Specifically, the drilling construction parameters in S1 are clarified, and the drilling hole diameter parameters are determined by the effective influence radius of the drilling hole. The compressive strength of the coal body, the distribution of cracks inside the coal body, and the stress concentration in the coal body all affect the effective radius of the drilling hole.

[0022] Specifically, in the drilling construction of S2, holes are drilled along the coal seam from the coal seam in the designated dangerous area into the coal body. The total length of the drilling is the sum of the drilling in the pressure relief section and the drilling in the gas extraction section.

[0023] Specifically, after the S2 drill bit is constructed to the designed length, compressed air is used to flush out the coal and rock powder in the hole, and a screen pipe is lowered into the hole. After the screen pipe is lowered to the designed position, the hole is sealed at the corresponding position, and a gas extraction pipeline connecting the gas extraction section to the coal wall of the tunnel is buried.

[0024] Specifically, the borehole diameters of the pressure relief section and the gas extraction section may be different, which are jointly determined by the risk assessment of rock burst disaster and the risk assessment of gas disaster.

[0025] Specifically, when sealing the hole, the sealing pump grouting pipe is connected to the bag sealer to start grouting. The explosion valves inside the inner and outer bags are modified. When they are under pressure, the explosion valves start to open, and the bags inside and outside the sealer are filled first. After the bags are filled, due to pressure, the explosion valves in the sealing section open, and cement slurry starts to be injected into the sealing section along the grouting pipe, and the air in the sealing section is discharged along the air guide pipe. When cement slurry flows out of the air guide pipe, it means that the sealing is completed.

[0026] Specifically, after the drilling construction is completed, the pressure relief section collapses and relieves pressure due to the stress of the coal body, and the gas extraction section is connected to the pipeline for gas extraction.

[0027] Specifically, the gas extraction pipe in the pressure relief section is covered with a water film. The purpose of borehole pressure relief is to break and collapse the coal body around the hole under the action of stress, expand the cracks and release the stress. However, it is difficult to evaluate whether the collapse inside the borehole is sufficient. After the gas extraction pipe in the pressure relief section is covered with a film bag, liquid is flushed into the film bag. When the hole collapses, the liquid is discharged from the coal wall at the side of the roadway through the drainage pipe. Due to the incompressibility of the liquid, a flow meter is installed in the side section of the borehole to calculate the collapsed area of ​​the hole. In addition, the film bag can seal the voids in the gas extraction pipe in the pressure relief section to enhance the gas extraction effect.

[0028] Specifically, the formula for calculating the proportion of collapsed holes is:

[0029] Where: V is the liquid outflow volume monitored by the flow meter, in cm 3 ; R is the diameter of the film, in cm; L is the length of the pressure relief section, in cm; b is the thickness of the film, in cm.

[0030] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0031] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for preventing and controlling coal-rock gas compound disasters based on coal seam drilling, characterized in that: The following steps are involved: S1: Determine the complex disaster hazard area based on rock burst, gas disaster risk assessment and actual monitoring data of the mine and other influencing factors, and clarify the drilling construction parameters; S2: Drill holes in the coal seam according to the complex disaster risk area determined in S1, and cover the gas extraction pipe with water film in the pressure relief section; S3: When the drilling construction in this composite disaster hazard area is completed, move to the next hazard area until all the designated coal-rock gas composite disaster hazard areas are covered and the prevention and control project is completed.

2. The method for preventing and controlling coal-rock gas compound disasters based on coal seam drilling according to claim 1 is characterized in that: The influencing factors for evaluating the composite disaster risk area in S1 are: Factors affecting gas disasters include: coal seam thickness, coal seam inclination, coal solidity coefficient, roof and floor lithology, gas pressure, coal seam gas content, initial velocity of gas outflow from drilling holes, and gas desorption index of drill cuttings; The factors affecting rock burst disasters include: multi-factor coupling method, comprehensive index method and factors mentioned in impact tendency identification.

3. The method for preventing and controlling coal-rock gas compound disasters based on coal seam drilling according to claim 1 is characterized in that: The drilling construction parameters in S1 include: drilling hole diameter, hole spacing, total drilling construction length, pressure relief section length, gas extraction section length, and sealing hole length.

4. The method for preventing and controlling coal-rock gas compound disasters based on coal seam drilling according to claim 1 is characterized in that: The drilling construction parameters in S1 are clarified. The drilling hole diameter parameters are determined by the effective influence radius of the drilling hole. The compressive strength of the coal body, the distribution of cracks inside the coal body, and the stress concentration inside the coal body all affect the effective radius of the drilling hole.

5. The method for preventing and controlling coal-rock gas compound disasters based on coal seam drilling according to claim 1 is characterized in that: The S2 covers the gas extraction pipe in the pressure relief section with a water film. The purpose of drilling pressure relief is to break the coal body around the hole and collapse it under the action of stress, expand the cracks and release the stress. However, it is difficult to evaluate whether the collapse inside the borehole is sufficient. After the gas extraction pipe in the pressure relief section is covered with a film bag, liquid is flushed into the film bag. When collapse occurs, the liquid is discharged from the coal wall of the roadway through the drainage pipe. Due to the incompressibility of the liquid, the collapsed area in the hole can be calculated, and the film bag can seal the voids in the gas extraction pipe in the pressure relief section to enhance the gas extraction effect.

6. According to the method for preventing and controlling coal-rock gas composite disasters based on coal seam drilling according to claim 5, the formula for calculating the proportion of collapsed holes is: Where: V is the liquid outflow volume monitored by the flow meter, in cm 3 ; R is the diameter of the film, in cm; L is the length of the pressure relief section, in cm; b is the thickness of the film, in cm.

7. The method for preventing and controlling coal-rock gas compound disasters based on coal seam drilling according to claim 1 is characterized in that: In S3, after the construction of the integrated pressure relief and extraction borehole in the complex disaster risk area, the elastic energy accumulated inside the coal body on the coal wall side is released, the high stress is transferred to a deeper level, and the gas contained in the coal body is extracted. The gas concentration and gas pressure are reduced, achieving the joint prevention and control of rock burst disasters and gas disasters.

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