CN115559770A - Coal roadway driving face gas outburst elimination pre-extraction treatment method - Google Patents
Coal roadway driving face gas outburst elimination pre-extraction treatment method Download PDFInfo
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Abstract
The invention belongs to the field of gas prevention and control in coal mining, and particularly relates to a gas outburst elimination pre-extraction treatment method for a coal roadway driving face, which comprises the steps of performing advanced geological drilling on the coal roadway driving face, detecting the inclination angle change and geological structure distribution condition of a coal seam, and adjusting the coal roadway inclination angle in subsequent construction according to the detection; developing liquid CO 2 Testing the phase change cracking radius; making an outburst elimination pre-extraction drilling hole arrangement scheme of a coal roadway driving face; formulating a outburst elimination pre-drainage drilling construction and extraction scheme of a coal roadway driving working face, and monitoring and recording gas extraction parameters; the coal seam gas extraction rate and the residual gas quantity are measuredCalculating, and after the gas extraction rate of the coal roadway driving face reaches the standard and no gas outburst risk exists, starting driving the coal roadway driving face; and (6) circulating. The method can reduce the gas outburst risk during coal roadway tunneling to the maximum extent, is beneficial to improving the gas extraction rate and the gas extraction speed of the coal seam, reducing the gas overrun frequency of the tunneling working face and fully utilizing the gas resources of the coal seam.
Description
Technical Field
The invention belongs to the field of gas control in coal mining, and particularly relates to a gas outburst elimination pre-extraction treatment method for a coal roadway driving face.
Background
With the long-term large-scale development of coal resources, deep mining with the depth reaching 800m or more has become a new normal state for coal resource development. Under the common influence of factors such as buried depth, high ground stress, high ground temperature and the like, deep coal mining faces the series problems of increased gas emission quantity, increased gas pressure and sudden abnormal local gas emission, and the threat of the mine caused by gas disasters is directly aggravated. Gas is a typical greenhouse gas, and the greenhouse effect and the damage to the ozone layer caused by the gas are CO 2 21 times and 7 times. Meanwhile, the gas is a clean and efficient energy resource and chemical raw material, the coal bed gas extraction force is increased, the coal bed gas content is reduced to the maximum extent, the deep coal mine safe and efficient mining can be guaranteed, the atmospheric environment protection is promoted, meanwhile, the coal bed gas resource is favorably fully utilized, and the economic benefit of a mine is improved.
The coal mine gas outburst accident mainly occurs on a coal roadway tunneling working face, the outburst times account for more than 70% of the total outburst number, and the main reason is that the tunneling working face is generally less influenced by mining, and gas in the peripheral coal seam is still in the original endowmentThe state is preserved, and gas pressure is great, and the headwork face is compared with coal face space limited simultaneously, and the gas is gushed more concentratedly. The high-gas coal seam generally has the natural properties of low gas permeability, strong adsorbability and low desorption speed, and has the advantages of high gas extraction difficulty, low efficiency, small influence range, long standard reaching time and high attenuation speed, so in order to eliminate the gas outburst risk of the coal seam, artificial permeability increase is required to improve the gas extraction rate and shorten the pre-extraction time. At the present stage, the permeability increasing method of the high gas low permeability coal seam mainly comprises hydraulic fracturing, hydraulic slotting, explosive blasting, CO 2 Phase change blasting, shock wave induced cracking, etc., wherein CO 2 The phase change blasting has the dual gas enhanced extraction functions of fracturing permeability improvement and displacement replacement, namely, on one hand, the gas is extracted by liquid CO 2 The instant gasification and expansion leads the coal body to generate new cracks, improves the air permeability of the coal bed, and on the other hand, fully utilizes CO 2 The adsorbability to coal bodies is stronger than that of CH 4 The method has the characteristics of displacing gas in the coal body. In view of the above, research on a CO-based catalyst 2 The fracturing permeability-increasing coal roadway driving face gas outburst elimination pre-extraction treatment method has important significance for improving the coal seam gas extraction rate and extraction speed, reducing the coal seam gas content and pressure, eliminating the gas outburst risk during coal roadway driving and realizing safe, efficient and green mining of deep coal mines.
Disclosure of Invention
The invention provides a method for solving the problem of gas outburst disasters of a tunneling working face of a deep high-gas coal seam 2 The fracturing permeability-increasing coal roadway tunneling working face gas outburst elimination pre-extraction treatment method is beneficial to improving the gas extraction effect of a high-gas coal seam, reducing the gas over-limit frequency of the tunneling working face, eliminating the gas outburst risk during tunneling, fully utilizing coal seam gas resources and guaranteeing safe, efficient and green mining of deep coal mines.
The method comprises the following specific steps:
a. performing advanced geological drilling on a coal roadway driving working face, detecting the inclination angle change of a coal seam and the distribution condition of a geological structure, and measuring the original content of coal seam gas; adjusting the coal roadway inclination angle during subsequent construction to be the same as the coal roadway inclination angle based on the coal seam inclination angle change value;
preferably, in the step a, the drilling depth is designed to be 120m, and the coal roadway is designed to be axially tunneled, wherein the designed axial direction of the coal roadway is the estimated coal seam development direction.
Preferably, in the step a, when the advanced geological drilling borehole enters the top plate or the bottom plate of the coal seam, a coal seam inclination angle change value is determined, and the advanced geological drilling borehole inclination angle is adjusted according to the coal seam inclination angle change value, so that the advanced geological drilling borehole is arranged parallel to the coal seam, and the designed drilling depth is still 120m.
Preferably, in the step a, when the advance geological drilling borehole enters the geological structure, the drilling is immediately retreated, and the advance outburst pre-drawing distance is changed from 120m to the actual drilling depth.
b. Developing liquid CO on coal wall of coal roadway driving face 2 Testing the phase change cracking radius R;
preferably, in the step b, extraction holes are arranged at two sides of the fracturing hole at different intervals, 19 drill holes are arranged in total, the number of the drill holes comprises 1 fracturing hole and 18 extraction holes, and the fracturing hole and the extraction holes Kong Kongshen are 15m; the 1# fracturing hole is arranged in the middle, the 1# fracturing hole and the left 2# to 8# extraction holes are arranged in a three-flower-hole mode at a distance of 1.0m, and the vertical distance between adjacent drill holes is 0.5m; the 1# fracturing hole and the right 9# to 19# extraction holes are arranged in a variable-pitch mode, the pitch value is gradually reduced from 1.3m to 0.5m and then is kept unchanged, and the vertical pitch of the adjacent drill holes is 0.5m.
Further, after the arrangement of the extraction holes is finished, timely sealing the holes and respectively installing a gas pressure gauge, recording the gas pressure of each extraction hole after the pressure of the gas pressure gauge is stabilized, then removing the gas pressure gauge, installing a gas comprehensive parameter measuring instrument to measure the natural gas flow of each extraction hole, monitoring for 10 days, and obtaining the average value of the gas extraction concentration and the extraction purity in each extraction hole; implementation of liquid CO in a fractured well 2 And (3) phase change fracturing, namely continuously acquiring the related data after coal body fracturing is finished, and determining liquid CO by comparing the gas extraction concentration before and after each extraction Kong Zhilie with the average value of the extraction pure quantity 2 Phase change cracking radius.
c. Making an outburst elimination pre-extraction drilling hole arrangement scheme of a coal roadway driving face: (1) arranging four rows of drill holes according to equal row spacing, wherein all the drill holes in the two extraction rows are extraction holes, and the fracture holes and the extraction holes in the two rows of fracture extraction rows are arranged in a staggered manner; (2) the extraction rows and the fracturing extraction rows are arranged at intervals, and the total number of the drill holes in the fracturing extraction rows is one more than that of the drill holes in the extraction rows; (3) two adjacent rows of drill holes are arranged in a three-flower-hole mode, and the fracturing holes in the two fracturing extraction rows are arranged in a staggered mode; (4) the number of fracturing holes in each fracturing extraction row is not less than three; (5) taking R/8-R/4 of the distance between adjacent drill holes and the row distance R, and determining the total number of the drill holes to be arranged according to the actual size of the cross section of the coal roadway; (6) the drill holes in each row are arranged in a divergent mode parallel to the inclination angle of the coal seam, and the drill holes in the rows are mutually staggered in the overlooking plane.
Preferably, in step c, the uppermost part is a fractured extraction row.
Preferably, in the step (6) of the step c, the final hole position of the middle hole is located in a vertical plane which is 120m away from the heading face of the tunneling working face or has the back drilling depth along the axial direction of the coal roadway, the left and right boundaries of the vertical plane are respectively 15m away from the corresponding coal roadway sides, the horizontal distance of the middle hole at the final hole position is (b + 30)/(n-1), wherein b is the width of the coal roadway, n is the number of the middle holes, and the depth of the middle hole and the included angle value between the depth of the middle hole and the axial direction of the coal roadway can be determined according to the opening position of the middle hole and the final hole position; the final hole positions of the boundary holes are controlled to be 15m away from the contour lines of the two sides of the coal roadway, the boundary hole position parameters with the maximum included angle with the axial direction of the coal roadway can be determined according to the minimum distance between the boundary holes and the heading of the tunneling working face along the axial direction of the coal roadway and the designed hole opening positions of the heading of the tunneling working face, the minimum included angle between the boundary hole position with the maximum included angle and the middle hole position in the overlooking plane is divided into m equal parts, m is 0.5 time of the number of the boundary holes, the intersection points of the angle equal lines and the boundary contour lines 15m away from the two sides of the coal roadway are the projection points of the other boundary holes in the overlooking plane, and the specific hole position parameters of the other boundary holes are determined according to the designed hole opening positions of the other boundary holes.
d. Making a outburst elimination pre-extraction drilling construction and extraction scheme of a coal roadway driving working face, and monitoring and recording gas pressure, flow speed and concentration parameters of each drilling hole and a summary network;
preferably, the extraction pipe is arranged in advance after the extraction hole is formedIn the hole, the hole sealing and the extraction are carried out as soon as possible, and liquid CO is carried out in time after the hole is cracked and formed 2 Phase change leads to cracking.
Preferably, before the fracturing hole is constructed, the extraction hole close to the periphery of the fracturing hole is constructed, and the fracturing hole is positioned in CO 2 And after the phase change fracturing is finished, the fracturing hole is used as an extraction hole.
e. Calculating the coal seam gas extraction rate and the residual gas quantity, and after the gas extraction rate of the coal roadway driving face reaches the standard and no gas outburst risk exists, starting driving the coal roadway driving face;
f. and (4) stopping construction after the coal roadway tunneling working face tunnels to a preset lower-circulation outburst elimination pre-pumping position, and continuously and repeatedly finishing the outburst elimination pre-pumping work according to the steps a-e.
Preferably, the specific range of the advanced outburst elimination pre-extraction area of the coal roadway driving face is 120m in length right in front of the driving face or 15+ b +15m in depth of bit withdrawal of the advanced geological drilling, wherein b is the width of the coal roadway, the left side and the right side of the coal roadway are respectively increased by 15m and are cuboid areas with the height of the coal roadway, the interval of the coal roadway driving face is 100m, the bit withdrawal depth is reduced by 20m during the bit withdrawal, and an outburst elimination pre-extraction drill site is constructed, namely the overlapping length of two adjacent advanced outburst elimination pre-extraction areas is 20m.
Has the advantages that: the invention provides a method based on CO 2 The fracturing permeability-increasing coal roadway driving face gas outburst elimination pre-extraction treatment method can reduce gas outburst risks during coal roadway driving to the maximum extent, is beneficial to improving coal seam gas extraction rate and extraction speed, reducing gas overrun frequency of a driving face and fully utilizing coal seam gas resources, and has important practical significance for guaranteeing safe, efficient and green mining of deep coal mines.
Drawings
FIG. 1 is a schematic diagram of an implementation flow of a gas outburst elimination pre-extraction treatment method for a coal roadway driving face;
FIG. 2 is liquid CO 2 A drilling hole arrangement schematic diagram of a phase change fracturing radius field test;
FIG. 3 is a schematic diagram of the arrangement principle of head-on outburst elimination pre-extraction drilling holes on a coal roadway driving face;
FIG. 4 is a schematic diagram of the arrangement of head-on outburst elimination pre-extraction drill holes on the coal roadway driving face in the embodiment;
FIG. 5 is one of the plan views (top view) of the arrangement of the outburst elimination pre-extraction drill holes of the coal roadway heading face in the embodiment;
FIG. 6 is a second plan view (top view) of the arrangement of the outburst elimination pre-extraction drill hole of the coal roadway driving face in the embodiment;
FIG. 7 shows specific arrangement parameters of fracturing extraction drill holes of a coal roadway driving face in the embodiment.
Detailed Description
As shown in fig. 1, a coal roadway driving face gas outburst elimination pre-extraction treatment method comprises the following steps:
a. performing advanced geological drilling on a coal roadway driving working face, detecting the inclination angle change of a coal seam and the distribution condition of a geological structure, and measuring the original content of coal seam gas; adjusting the coal roadway inclination angle during subsequent construction based on the coal seam inclination angle variation value;
specifically, a drill bit with the diameter of 94mm is selected to perform advanced geological drilling on the heading face of the coal roadway along the axial direction of the coal roadway (namely the design heading direction of the coal roadway, which is specifically determined when a layout scheme of a stope face is designed), and the design drilling depth is 120m.
When the situation that the drill hole enters a coal seam roof or floor is judged according to the conditions of hole opening slag tapping, coring and the like, the drill hole is immediately withdrawn, the change value of the coal seam inclination angle is measured, and the determination method comprises the following steps: knowing the depth of the back drilling and the drilling angle, sequentially calculating the height difference and the horizontal distance between the drilling position and the back drilling position through sine and cosine functions, continuously determining the height difference between the head-on top plate/bottom plate and the top/bottom plate of the back drilling position of the tunneling working face according to the vertical distance between the drilling position and the top plate/bottom plate, and finally determining the change value of the coal seam inclination angle according to the tangent value of the coal seam inclination angle = (the vertical height difference of the top plate/bottom plate)/the horizontal distance. And adjusting the inclination angle of the advanced geological drilling hole (the included angle between the advanced geological drilling hole and the horizontal plane) according to the change value of the coal bed inclination angle, ensuring that the advanced geological drilling hole is arranged in parallel to the coal bed, and designing the drilling depth to be 120m. After the advanced geological drilling is finished, the inclination angle of the outburst elimination pre-drilled hole (including a fracturing hole and an extraction hole) in the follow-up construction is adjusted according to the inclination angle of the coal bed, namely the included angle between the outburst elimination pre-drilled hole and the horizontal plane is adjusted. The outburst elimination pre-pumping drill holes are all bedding drill holes, namely are arranged in parallel to the coal seam, and the inclination angle of the outburst elimination pre-pumping drill holes and the inclination angle of the coal roadway are equal to the inclination angle of the coal seam.
When the situation that the drill hole enters a fault, a fold and other geological structures is judged according to the conditions of hole opening slag tapping, core taking and the like, the drill is immediately withdrawn, the distance between the drill hole and the front geological structure is measured, and the advance outburst elimination pre-pumping distance is changed from 120m to the actual drilling depth; and adjusting the drilling depth of the outburst elimination pre-extraction drill holes (including the fractured holes and the extraction holes) in the follow-up construction based on the actual drilling depth.
When the hole depth of the advanced geological drilling hole reaches 120m or the drilling is withdrawn, a core drilling machine is used for obtaining a fresh coal sample, the fresh coal sample is stored in a sealed mode, and the fresh coal sample is sent to a laboratory to be used for measuring the original content of the coal bed gas by adopting a gas content direct measuring device and a gas component analyzer; and after the advanced geological drilling coring is finished, the hole is timely sealed, and the hole can be subsequently used as a fracturing hole or an extraction hole.
b. Developing liquid CO on coal roadway driving face 2 Testing the phase change cracking radius;
liquid CO 2 The phase change fracturing technology is a coal bed permeability increasing technology based on physical blasting, and utilizes liquid CO 2 The coal bed is cracked by the blasting impact effect of instantaneous high-pressure gas generated by phase change on the coal bed around the drill hole, so that the pressure of gas in the coal bed is relieved, and the aims of reducing the gas content and eliminating the gas outburst risk are fulfilled. Should be based on coal seam properties (coal seam hardness and brittleness and plasticity), liquid CO 2 Comprehensively determining CO by actual factors such as phase change cracking process parameters, construction level of operators and the like 2 The phase change fracturing radius further provides reasonable parameter selection basis for the arrangement scheme of the outburst elimination pre-pumping drill holes (including fracturing holes and extraction holes) on site, so that the outburst elimination pre-pumping effect of gas on the coal roadway driving face is ensured, the construction workload of the drill holes is reduced, the coal seam gas pre-pumping time is shortened, and the safe and efficient mining of a mine is ensured.
In particular, for enhancing liquid CO in coal body 2 The actual measurement precision of the phase change cracking radius is tested, and simultaneously the liquid CO is tested 2 Selecting the coal wall of the side part of a driving face to enter the coal bed gas extraction effect after phase change fracturingLiquid CO 2 Phase change fracturing radius test, after determining the specific position of the fracturing hole, respectively arranging extraction holes at different intervals on two sides of the fracturing hole, as shown in fig. 2, arranging 19 drill holes in total, wherein the drill holes comprise 1 fracturing hole and 18 extraction holes, and the fracturing holes and the extraction holes Kong Kongshen are 15m; the 1# fracturing hole is arranged in the middle, the 1# fracturing hole and the left 2# to 8# extraction holes are arranged in a three-flower-hole mode at a distance of 1.0m, and the vertical distance between adjacent drill holes is 0.5m; liquid CO from past construction experience 2 The phase change fracturing radius is generally 2.0-6.5 m, and meanwhile, if the distance between adjacent extraction holes is too small, hole collapse is easy to occur in the drilling process, so that the 1# fracturing hole and the 9# to 19# extraction holes on the right side are comprehensively determined to be arranged in a variable-distance mode, the distance value is gradually reduced from 1.3m to 0.5m and then is kept unchanged, and the vertical distance between the adjacent drilling holes is still 0.5m;
after the arrangement of each extraction hole is finished, timely sealing the hole and respectively installing a gas pressure gauge, recording the gas pressure of each extraction hole after the pressure of the gas pressure gauge is stable, then removing the gas pressure gauge, installing a gas gauge (or a gas comprehensive parameter measuring instrument) to measure the natural gas flow of each extraction hole, wherein the monitoring time is 10 days, and obtaining the stable average value of the gas extraction concentration and the pure quantity in each extraction hole; after the test is finished, liquid CO is pushed by the pushing rod 2 The phase change fracturing device is placed in the fracturing hole and then sealed, and the liquid CO is implemented by the operating personnel 2 Phase change cracking; continuously acquiring the related data after the coal body fracturing is finished, and determining liquid CO by comparing the average values of the gas extraction concentration and the extraction purity before and after each extraction Kong Zhilie 2 Phase change cracking radius.
c. Based on liquid CO 2 According to the phase change fracturing radius test result, establishing an arrangement scheme of outburst elimination pre-pumping drill holes (including fracturing holes and extraction holes) of the coal roadway driving face;
referring to fig. 3, the outburst elimination pre-extraction drill holes (including the fracturing holes and the extraction holes) of the coal roadway driving face are specifically arranged as follows: (1) Arranging four rows of drill holes according to the equal row spacing, wherein all the drill holes in the two rows are extraction holes, namely extraction rows, and the fracture holes and the extraction holes in the other two rows are arranged in a staggered mode, namely the fracture extraction rows; (2) The extraction rows and the fracturing extraction rows are arranged at intervals, and the fracturing extraction rows are arranged in the fracturing extraction rowsThe total number of the drill holes is 1 more than that of the drill holes in the extraction row, so that each extraction hole is ensured to be close to one fracturing hole, and the uppermost part is preferably the fracturing extraction row; (3) Two adjacent rows of drill holes are arranged in a three-flower-hole mode, and the fracturing holes in the two fracturing extraction rows are arranged in a staggered mode; (4) The number of fracturing holes in each fracturing extraction row is not less than three; (5) If the liquid CO is determined by field actual measurement 2 When the phase change fracturing radius is R, the total number of the drill holes to be arranged can be determined according to the actual size of the section of the coal roadway after determining that the distance between adjacent drill holes and the row spacing R can be determined according to R/8-R/4,r values by comprehensively considering factors of improving the gas extraction purity, shortening the gas pre-extraction time of a coal seam, reducing the workload of drilling construction and the like and combining engineering experience; (6) All rows of drill holes are arranged in a divergent manner parallel to the inclination angle of the coal seam, and the drill holes in the rows are staggered with each other in a top-down plane, the final hole position of each middle hole is positioned in a vertical plane which is 120m away from the head of the tunneling working face or the back drilling depth along the axial direction of the coal roadway, the left and right boundaries of the vertical plane are respectively 15m away from the corresponding coal roadway side, the horizontal distance of the middle hole at the final hole position is (b + 30)/(n-1) m (wherein b is the width of the coal roadway, n is the number of the middle holes, and the depth of the middle hole and the axial included angle value of the middle hole and the coal roadway can be determined according to the opening position of the middle hole and the final hole position; the final hole position of the boundary hole is controlled to be 15m outside the contour lines of the two sides of the coal roadway, the minimum distance between the boundary hole and the heading face along the axial direction of the coal roadway is designed to be 29.5m according to engineering experience, based on the minimum distance, the position of the boundary hole with the largest axial included angle with the coal roadway can be determined according to the designed hole opening position of the heading face, the minimum included angle formed by the position of the boundary hole and the position of the middle hole in the overlooking plane is divided into m equal parts (m is 0.5 time of the number of the boundary holes), the intersection point of the angle equal dividing line and the boundary contour lines 15m away from the two sides of the coal roadway is the projection point of other boundary holes in the overlooking plane, and the specific hole position parameters of other boundary holes can be determined according to the designed hole opening positions of other boundary holes.
In this embodiment, as shown in fig. 4 to 6, a reasonable outburst elimination pre-drainage scheme is formulated according to the properties of the coal seam (the hardness and brittleness of the coal seam) and the size of the coal roadway, so as to improve the air permeability of the coal seam, reduce the gas content and pressure of the coal seam, and shorten the gas pre-drainage timeThe gas outburst risk during tunneling is eliminated, and the coal mine is guaranteed to be safely and efficiently mined. The size of the cross section of the coal roadway is 4.8m multiplied by 3.0m, and the test result in the step b shows that the liquid CO is in a liquid state 2 The phase change fracturing radius is 4.5-5.0 m, the row spacing r between adjacent drill holes is determined to be 0.7m according to the arrangement principle of outburst elimination pre-extraction drill holes of a coal roadway driving working face, and then the total number of the drill holes is determined to be 26, wherein 7 fracturing holes and 19 extraction holes, namely 2#, 6#, 10#, 14#, 18#, 21#, and 25# drill holes are fracturing holes, 1#, 3#, 4#, 5#, 7#, 8#, 9#, 11#, 12#, 13#, 15#, 16#, 17#, 19#, 20#, 22#, 23#, 24#, and 26# drill holes are extraction holes, specific arrangement parameters of each fracturing hole and extraction hole are shown in detail in figure 7, and a positive and negative judgment method for an axial included angle between each drill hole and the coal roadway is that the coal roadway rotates in the counterclockwise direction, and the clockwise rotation is a negative hole site.
d. Designing a construction and extraction scheme corresponding to each drill hole based on an outburst elimination pre-extraction drill hole (including a fracturing hole and an extraction hole) arrangement scheme, and monitoring and recording parameters such as gas pressure, flow rate and concentration of each drill hole and a summary network;
when drilling, the position of a drilling machine needs to be fixed, a drill bit with the diameter of 94mm is selected to carry out construction strictly according to the arrangement scheme of a fracturing hole and an extraction hole, slow propulsion is adopted to ensure that the hole body is straight, the inner wall is smooth, the hole is clean, and residues in the hole need to be blown off completely before the drill is withdrawn; if the hole stringing phenomenon occurs, hole repairing is needed again; in order to prevent the collapsed hole from generating adverse effects on subsequent fracturing and extraction, the extraction pipe can be arranged in the hole in advance after the hole is formed in the extraction hole, hole sealing and combined extraction are carried out as soon as possible, and operating personnel need to be informed of liquid CO after the hole is fractured and formed 2 And (4) phase transformation cracking.
After the construction of each extraction hole is completed, hole sealing is carried out in time in a 'two-plugging and one-injecting' mode, namely, firstly, both ends of a hole sealing section are sealed by bagged polyurethane, then, a drilling hole section between the two polyurethane sealing sections is injected by a grouting pipe, and under the action of grouting pressure, grout penetrates through the hole wall and fills cracks around the drilling hole so as to improve the sealing performance of the hole sealing.
Shi Gongzhi before cracking, firstly constructing extraction holes which are close to the periphery of the hole to be used as pressure relief holes of a cracking hole,in the process of liquid CO 2 Before phase change cracking, monitoring gas and CO in coal roadway 2 When the concentration of the gas is lower than 0.8 percent, CO 2 When the concentration is less than 0.5%, the phase change cracking can be carried out.
In this embodiment, the outburst elimination pre-extraction drilling construction and extraction scheme for the coal roadway driving face specifically includes: (1) the construction sequence of each drilling hole is as follows: 3#, 4#, 5# gas drainage holes → 2# fracturing holes → 1#, 8#, 9# gas drainage holes → 6# fracturing holes → 7#, 11#, 12#, 13# gas drainage holes → 10# fracturing holes → 16#, 17# gas drainage holes → 14# fracturing holes → 15#, 19#, 20#, 22# gas drainage holes → 18# fracturing holes → 24#, 26# gas drainage holes → 21# fracturing holes → 23# gas drainage holes → 25# fracturing holes; (2) After construction is completed, timely hole sealing and networking negative pressure pre-pumping are carried out, and after the gas flow tends to be stable, corresponding fracturing holes are constructed; (3) After the construction of each fracturing hole is finished, a related fracturing device is installed in the hole, and after the installation is finished, liquid CO is implemented 2 Phase change induced cracking, CO 2 After the phase change fracturing is finished, the fracturing holes are used as extraction holes and are merged into a gas extraction gathering network for negative pressure pre-extraction; (4) After the gas flow of the extraction and summarization network tends to be stable, carrying out the construction of the next group of extraction holes according to the design sequence; (5) And monitoring and recording parameters such as gas pressure, flow velocity, concentration and the like of each drilling hole and the summary network in the whole gas extraction process.
e. Calculating the coal seam gas extraction rate and the residual gas amount, and after the gas extraction rate of the coal roadway driving face reaches the standard and no gas outburst risk exists, starting driving the coal roadway working face;
according to actually measured data of a gas extraction field, calculating the gas extraction rate and the residual gas quantity of a coal seam, if the calculation result meets the standard requirement of the gas extraction rate of a driving face and meets the judgment standard of no gas outburst risk, arranging 3 inspection drill holes at the spatial positions of a middle hole and a boundary hole in the head-on reference of the driving face, verifying the residual gas content of the coal seam, and finally determining that the gas extraction rate of the driving face reaches the standard and no gas outburst risk exists in a cyclic propulsion distance, and then starting driving the coal roadway face;
the calculation formula of the gas extraction rate eta is as follows:
in the formula, Q mj Average gas extraction quantity m of the driving face during extraction 3 /min；Q mf For extracting the average air exhaust gas quantity m of the driving working face during the period 3 /min。
Residual gas W of extracted coal seam cy The calculation formula of (a) is as follows:
in the formula, W 0 Is the original gas content of the coal body, m 3 T; g is the coal reserve, t, of the evaluation unit participating in the calculation; q is the total gas quantity of the evaluation unit drilling drainage, m 3 。
The coal reserves G of which the evaluation unit participates in the calculation are calculated by the following formula:
G＝(L+2R)(l+R)mγ
in the formula, L is the strike length of the evaluation unit coal seam, m; l is the average inclined length m of the coal bed in the extraction hole control range of the evaluation unit; r is the effective influence radius of the extraction hole, m; m is the average coal seam thickness of the evaluation unit; gamma is the density of the coal body of the evaluation unit, t/m 3 。
The standard reaching requirement of the gas extraction rate of the coal roadway driving face is as follows: the content of original gas in coal bed is less than 10m 3 At the time of/t, the gas extraction rate eta is not lower than 35%; the original gas content of the coal bed is 10m 3 /t～15m 3 For the gas extraction rate of the gas extraction system,/t, the gas extraction rate eta is not lower than 45%; the original gas content of the coal bed is 15m 3 And the gas extraction rate eta is not less than 60% above the t.
According to the regulations on preventing and controlling coal and gas outburst, the specifications of coal mine gas extraction, the basic indexes of coal mine gas extraction and the coal seamResidual gas pressure less than 0.74MPa or residual gas content less than 8m 3 The pre-pumping area of/t is a gas-free outburst danger area.
f. And (4) stopping construction after the coal roadway tunneling working face tunnels to a preset lower-circulation outburst elimination pre-pumping position, and continuously and repeatedly finishing the outburst elimination pre-pumping work according to the steps a-e.
Specifically, the specific range of the advanced outburst elimination pre-extraction area of the coal roadway driving face is a cuboid area with the length right in front of the driving face being 120m or the advance geological drilling bit retreating depth, the width being (15 + b + 15) m (wherein b is the width of the coal roadway, the left side and the right side of the coal roadway are respectively increased by 15 m), and the height being the height of the coal roadway, the interval of the coal roadway driving face is 100m, the retreating depth is minus 20m during the retreating process, and an outburst elimination pre-extraction drill site is constructed, namely the overlapping length of two adjacent advanced outburst elimination pre-extraction areas is 20m.
Claims (10)
1. A coal road driving face gas outburst elimination pre-extraction treatment method is characterized by comprising the following specific steps:
a. performing advanced geological drilling on a coal roadway driving working face, detecting the inclination angle change of a coal seam and the distribution condition of a geological structure, and measuring the original content of gas in the coal seam; adjusting the coal roadway inclination angle during subsequent construction to be the same as the coal roadway inclination angle based on the coal seam inclination angle change value;
b. developing liquid CO on coal wall of coal roadway driving face 2 Testing the phase change cracking radius R;
c. the method comprises the following steps of (1) making an outburst elimination pre-extraction drilling hole arrangement scheme of a coal roadway driving face: (1) arranging four rows of drill holes according to equal row spacing, wherein all the drill holes in the two extraction rows are extraction holes, and the fracture holes and the extraction holes in the two rows of fracture extraction rows are arranged in a staggered manner; (2) the extraction rows and the fracturing extraction rows are arranged at intervals, the uppermost part is the fracturing extraction row, and the total number of the drill holes in the fracturing extraction row is one more than that of the drill holes in the extraction row; (3) two adjacent rows of drill holes are arranged in a three-flower-hole mode, and the fracturing holes in the two fracturing extraction rows are arranged in a staggered mode; (4) the number of fracturing holes in each fracturing extraction row is not less than three; (5) taking R/8-R/4 of the distance between adjacent drill holes and the row distance R, and determining the total number of the drill holes to be arranged according to the actual size of the cross section of the coal roadway; (6) the drill holes in each row are arranged in a divergent mode parallel to the inclination angle of the coal seam, and the drill holes in the rows are mutually staggered in the overlooking plane.
d. Making a outburst elimination pre-extraction drilling construction and extraction scheme of a coal roadway driving working face, and monitoring and recording gas pressure, flow speed and concentration parameters of each drilling hole and a summary network;
e. calculating the coal seam gas extraction rate and the residual gas quantity, and after the gas extraction rate of the coal roadway driving face reaches the standard and no gas outburst risk exists, starting driving the coal roadway driving face;
f. and (4) stopping construction after the coal roadway tunneling working face tunnels to a preset lower-circulation outburst elimination pre-pumping position, and continuously and repeatedly finishing the outburst elimination pre-pumping work according to the steps a-e.
2. The gas outburst elimination and pre-extraction treatment method according to claim 1, wherein in the step a, the designed drilling depth is 120m, axial tunneling is designed along a coal roadway, and the designed axial direction of the coal roadway is the estimated development direction of the coal bed.
3. The gas outburst elimination and pre-extraction treatment method according to claim 2, wherein in the step a, when the advanced geological drilling hole enters the top plate or the bottom plate of the coal seam, a coal seam inclination angle change value is determined, the inclined angle of the advanced geological drilling hole is adjusted according to the coal seam inclination angle change value, the advanced geological drilling hole is arranged in parallel with the coal seam, and the designed drilling depth is still 120m.
4. The gas outburst elimination and pre-extraction treatment method according to claim 3, wherein in the step a, when the advance geological drilling hole enters the geological structure, the drilling is immediately retreated, and the advance outburst elimination and pre-extraction distance is changed from 120m to the actual drilling depth.
5. The gas outburst elimination and pre-extraction treatment method according to claim 1, wherein in the step b, extraction holes are arranged at two sides of the fracturing hole at different intervals, 19 drill holes are arranged in total, the number of the drill holes comprises 1 fracturing hole and 18 extraction holes, and the fracturing holes and the extraction holes Kong Kongshen are 15m; the 1# fracturing hole is arranged in the middle, the 1# fracturing hole and the left 2# to 8# extraction holes are arranged in a three-flower-hole mode at a distance of 1.0m, and the vertical distance between adjacent drill holes is 0.5m; the 1# fracturing hole and the right 9# to 19# extraction holes are arranged in a variable pitch mode, the pitch value is gradually reduced to 0.5m from 1.3m and then is kept unchanged, and the vertical pitch of adjacent drill holes is 0.5m.
6. The gas outburst elimination and pre-extraction treatment method according to claim 5, characterized in that after the arrangement of each extraction hole is completed, the hole is sealed in time, a gas pressure gauge is installed respectively, after the pressure of the gas pressure gauge is stabilized, the gas pressure of each extraction hole is recorded, then the gas pressure gauge is removed, a gas comprehensive parameter measuring instrument is installed to measure the natural gas flow of each extraction hole, the natural gas flow is monitored for 10 days, and the average value of the gas extraction concentration and the extraction purity in each extraction hole is obtained; implementation of liquid CO in a fractured well 2 And (3) phase change fracturing, namely continuously acquiring the related data after coal body fracturing is finished, and determining liquid CO by comparing the gas extraction concentration before and after each extraction Kong Zhilie with the average value of the extraction pure quantity 2 Phase change cracking radius.
7. The gas outburst elimination and pre-extraction treatment method according to claim 4, wherein in the step (6) of the step c, the final hole position of the middle hole is located in a vertical plane which is 120m away from the head of the tunneling working face or the back-drilling depth along the axial direction of the coal roadway, the left and right boundaries of the vertical plane are respectively 15m away from the corresponding coal roadway sides, the horizontal distance of the middle hole at the final hole position is (b + 30)/(n-1) m, wherein b is the width of the coal roadway, n is the number of the middle holes, and the depth of the middle hole and the included angle value between the depth of the middle hole and the axial direction of the coal roadway can be determined according to the opening position and the final hole position of the middle hole; the final hole position of the boundary hole is controlled to be 15m away from the contour lines of the two sides of the coal roadway, the position parameter of the boundary hole with the maximum included angle with the axial direction of the coal roadway can be determined according to the minimum distance between the boundary hole and the heading face along the axial direction of the coal roadway and the designed hole opening position of the heading face, the minimum included angle between the position of the boundary hole with the maximum included angle and the position of the middle hole in the overlooking plane is divided into m equal parts, m is 0.5 time of the number of the boundary holes, the intersection point of the angle bisector and the boundary contour lines 15m away from the two sides of the coal roadway is the projection point of other boundary holes in the overlooking plane, and the specific hole position parameter of other boundary holes is determined according to the designed hole opening positions of other boundary holes.
8. The gas outburst elimination pre-extraction treatment method according to claim 1, characterized in that the extraction pipe is arranged in the hole in advance after the extraction hole is formed, hole sealing and combined extraction are carried out as soon as possible, and liquid CO is carried out in time after the hole is formed due to cracking 2 Phase change leads to cracking.
9. The gas outburst elimination pre-extraction treatment method according to claim 8, characterized in that extraction holes close to the periphery of the gas outburst elimination pre-extraction treatment method are firstly constructed before construction of the fracturing hole, and the fracturing hole is formed in CO 2 And after the phase change fracturing is finished, the fracturing hole is used as an extraction hole.
10. The gas outburst elimination pre-extraction treatment method as claimed in claim 4 or 7, wherein the specific range of the advance outburst elimination pre-extraction region of the coal roadway driving face is 120m in length right in front of the driving face or 15+ b +15m in width and the b is the width of the coal roadway, 15m is respectively added on the left side and the right side and is a cuboid region with the height of the coal roadway, the interval between the driving faces of the coal roadway is 100m, 20m is subtracted from the depth of the retreated drill during the retreating, and a outburst elimination pre-extraction drill site is constructed, namely the overlapping length of two adjacent advance outburst elimination pre-extraction regions is 20m.
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| CN116556966A (en) * | 2023-07-07 | 2023-08-08 | 山西凯嘉能源集团有限公司 | Roadway driving method for precisely eliminating coal roadway driving coal and gas outburst |
| CN116608004A (en) * | 2023-05-26 | 2023-08-18 | 中国矿业大学 | Discharging-extracting-tunneling cooperative prevention and control method for controlling rock burst and gas extraction |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116608004A (en) * | 2023-05-26 | 2023-08-18 | 中国矿业大学 | Discharging-extracting-tunneling cooperative prevention and control method for controlling rock burst and gas extraction |
| CN116608004B (en) * | 2023-05-26 | 2023-10-27 | 中国矿业大学 | Discharging-extracting-tunneling cooperative prevention and control method for controlling rock burst and gas extraction |
| CN116556966A (en) * | 2023-07-07 | 2023-08-08 | 山西凯嘉能源集团有限公司 | Roadway driving method for precisely eliminating coal roadway driving coal and gas outburst |
| CN116556966B (en) * | 2023-07-07 | 2023-09-19 | 山西凯嘉能源集团有限公司 | Roadway driving method for precisely eliminating coal roadway driving coal and gas outburst |
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