CN113309567A

CN113309567A - Method for accurately measuring position of coal seam roof fissure zone based on medium-pressure water injection

Info

Publication number: CN113309567A
Application number: CN202110579558.XA
Authority: CN
Inventors: 张明杰; 唐开敏; 江山; 唐振伟; 尚志坚; 孙谦; 张锐; 卞金岭; 刘思远; 谭志宏; 周巍
Original assignee: Henan University of Technology
Current assignee: Henan University of Technology
Priority date: 2021-05-26
Filing date: 2021-05-26
Publication date: 2021-08-27
Anticipated expiration: 2041-05-26
Also published as: CN113309567B

Abstract

The method for accurately measuring the position of the coal seam roof fissure zone based on medium-pressure water injection comprises the following steps of: preliminarily calculating the theoretical calculation values of the heights of the fracture zone and the caving zone; further determining the development height of the fissure zone; designing a hole distribution mode of a site water injection observation drill hole; constructing water injection drilling and hole sealing water injection operation according to different drilling hole distribution modes, and judging the development heights and zonal positions of the caving zone, the fractured zone and the bent sinking zone according to the water return condition of the drilling cooling water; hole sealing and water injection are carried out on site, and the height of a fracture zone and the development degree of a fracture are accurately measured according to water pressure and water quantity change; and comprehensively analyzing the measurement result and the occurrence condition of the coal seam of the well field, and determining the proper high-position drilling position of the fracture zone of the coal seam roof when gas is extracted. The method has the advantages of scientific principle, perfect theory, reliable measuring result, strong practicability, simple operation, universal and universal use of instruments and instruments, and is mainly used for solving the problem that the heights of the caving zone and the fissure zone in the mine gas extraction are difficult to determine.

Description

Method for accurately measuring position of coal seam roof fissure zone based on medium-pressure water injection

Technical Field

The invention belongs to the technical field of mine gas treatment, and particularly relates to a method for accurately measuring the position of a coal seam roof fissure zone based on medium-pressure water injection.

Background

After the coal seam is mined, the top plate of the goaf falls under the influence of dynamic pressure, and at the moment, a falling zone, a crack zone and a bent sinking zone can be generated. Due to the limitation of mining technology and mining conditions, the high gas mine and the coal and gas outburst mine have high gas emission amount, which easily causes the return air flow of the working face and the gas at the upper corner to exceed the limit, thereby forming potential safety hazards. At present, a coal seam roof fissure zone high-position drilling extraction technology is generally adopted. The mechanism is that the caving zone, the fissure zone and the bending subsidence zone formed on the top plate of the goaf by the stoping face are different in space height and permeability, the ventilation gas degree of the stoping face and the upper corner is different, and the extraction drill holes are arranged at the proper positions of the fissure zone with developed fissures, so that a large amount of high-concentration gas is extracted, and the purpose of preventing the gas from exceeding the limit is achieved. The heights of the caving zone and the fractured zone need to be known when gas accumulated in the fractured zone is drained, most of the existing methods are calculated by using empirical formulas, and the calculation of the empirical formulas is not accurate due to the complexity of roof rocks. The gas drainage is guided by using the height of the crack zone which is not accurate enough, and the effect cannot reach the best. Therefore, accurate fracture zone and caving zone heights need to be ascertained to achieve the best extraction effect. Therefore, the position of the coal seam roof fracture zone, namely the vertical height from the coal seam, needs to be accurately measured, and the extraction drill hole of the construction roof fracture zone is designed according to the measurement result.

Disclosure of Invention

The method for accurately determining the position of the fracture zone of the coal seam roof based on medium-pressure water injection is scientific in principle, easy to operate, high in accuracy and wide in application range.

In order to solve the technical problems, the invention adopts the following technical scheme: the method for accurately measuring the position of the coal seam roof fissure zone based on medium-pressure water injection comprises the following steps of:

firstly, performing theoretical analysis and calculation of an empirical formula according to the lithology of a roadway roof, and preliminarily calculating a theoretical calculation value of the heights of a fracture zone and an caving zone;

secondly, verifying through a numerical simulation research method to further determine the development height of the fractured zone;

thirdly, designing a hole distribution mode of on-site water injection observation drilling according to a specific spatial relationship between a construction drilling roadway and a mining surface;

fourthly, constructing water injection drilling and hole sealing water injection operation according to different drilling hole distribution modes, and judging the development heights and zonal positions of the caving zone, the fracture zone and the bending subsidence zone according to the water return condition of the drilling cooling water; hole sealing and water injection are carried out on site, and the height of a fracture zone and the development degree of a fracture are accurately measured according to water pressure and water quantity change;

and fifthly, comprehensively analyzing the measurement result and the occurrence condition of the coal seam of the well field, and determining the proper high-position drilling position of the fracture zone of the coal seam roof when gas is extracted.

Three hole distribution modes for on-site water injection observation drilling are designed in the third step:

the first mode is that under the condition that a tunnel is arranged above a coal seam roof, namely in a curved sunken zone, a proper place is selected from the tunnel at the upper part of the curved sunken zone; designing a drilling angle and a drilling depth according to the height of the fracture zone determined by the theory of the second step, and drilling a lower goaf in a pressurized water drilling mode; the height of the curved subsidence zone from the central line of the upper roadway to the coal bed below is X, the maximum angle at which a drilling machine can drill a downward drill hole is alpha, and the height of the caving zone determined by theory is H₁The height of the fissure zone determined by theory is H₂Based on the above data, the hole depth (X-H) of the position of the opening from the upper limit of the caving zone, i.e., the lower limit of the fractured zone, is obtained₁) A/cos alpha, the depth of the hole from the position of the opening to the upper limit of the fractured zone is (X-H)₁-H₂）/cosα；

The second mode is that under the condition that a roadway is arranged at the lower part of the coal seam floor, a proper place is selected to drill a hole in the inclined upward direction in the roadway at the lower part of the goaf, namely the bottom suction roadway; designing a drilling angle and a hole depth according to the height of the fracture zone determined by the theory of the second step, and drilling the upper goaf by adopting a pressurized-water drilling mode: the height of the bottom suction roadway from the coal seam is X, the drilling machine can drill the maximum angle alpha of the upward drill hole, and the height of the caving zone determined theoretically is H₁The height of the fissure zone determined theoretically is H₂According to the data, the hole depth (X + H) of the position of the open hole from the upper limit of the caving zone, namely the lower limit of the fractured zone is obtained₁) Sin alpha, the depth of the hole from the position of the hole to the upper limit of the fissure zone is (X + H)₁+H₂）/sinα；

The third mode is that under the condition that no laneway exists above the coal seam roof, namely in the bent subsidence zone and at the lower part of the coal seam floor, a proper place is selected to drill a hole obliquely upwards in the laneway adjacent to the goaf; determining the height of the fractured zone and the drilling site according to the theory of the second stepDrilling angles and hole depths are designed at the distance of the goaf, and drilling is carried out on the goaf close to the goaf in a pressurized-water drilling mode: the horizontal distance between the lower wall of the roadway close to the goaf and the upper wall of the goaf of the working face is X, and the height of the caving zone determined theoretically is H₁The height of the fissure zone determined theoretically is H₂And obtaining the angle during drilling design according to the data, wherein the maximum elevation angle of the lower limit of a drill site and an caving zone, namely a fracture zone in the roadway adjacent to the goaf is alpha = arctan (H)₁/X), the maximum elevation angle of the upper limit of a drilling field and a fracture zone, namely the lower limit of a bending subsidence zone is beta = arctan [ (H)₁+H₂)/X]Four boreholes were designed: 1^#The hole angle is alpha/2, 2^#The hole angle is alpha, 3^#The hole angle is (beta + alpha)/2, 4^#The hole angle is beta.

The fourth step is carried out in a first mode, and comprises the following specific steps:

firstly, a water injection drilling machine is used for drilling downwards, the depth of a drilling hole extends to the upper limit of a fracture zone, then the drilling is continued for 10-15m downwards, and a drilling rod is withdrawn;

secondly, connecting the special medium-pressure self-expansion type water injection hole packer with a water injection pipe, and conveying the special medium-pressure self-expansion type water injection hole packer connected with the water injection pipe to the hole bottom position of a drilled hole;

thirdly, testing the water pressure of water injection in the special medium-pressure self-expansion type water injection hole packer, radially expanding a tire bag of the special medium-pressure self-expansion type water injection hole packer to outwards press the inner wall of the drilled hole, and observing and recording the change condition of the water pressure gauge at any time in the water injection process until the water pressure gauge is stable;

fourthly, after the pressure of the tyre bag of the special medium-pressure self-expansion type water injection hole packer is relieved, the special medium-pressure self-expansion type water injection hole packer is moved upwards by taking 5m as a unit, the water injection water pressure test of the third step is repeated for multiple times, and the test is carried out until the test is near the position which is 10m above the theoretically determined fracture zone upper limit;

fifthly, contrastively analyzing the recorded water pressure stability value, wherein the water seepage speed is higher because the crack in the crack zone develops better permeability, the pressure reduction of the tyre bag of the medium-pressure self-expansion type hole packer in the crack zone is obvious, namely the pressure relief speed is high, the water pressure stability value is also smaller, the crack zone above the crack zone is low in non-development permeability of the crack in the bending subsidence zone, the water pressure reduction is not obvious in the water injection water pressure test, namely the pressure relief speed is low, the water pressure stability value is also larger, and the specific position of the upper limit of the crack zone, namely the lower limit of the bending subsidence zone is contrastively analyzed according to the phenomenon;

and sixthly, withdrawing the special medium-pressure self-expansion type water injection hole packer after the upper limit of the fractured zone is determined, continuously using a water injection drilling machine to drive a drill rod to drill until the drill rod drills into the fractured zone, and greatly reducing the water return degree of the water injection drilling machine until the water does not return when the drill hole enters the fractured zone.

The fourth step is carried out in a second mode, and the specific steps are as follows:

firstly, an upward drilling is carried out by using a water injection drilling machine, the water return degree is greatly reduced until the water return is not carried out when a drill rod penetrates through a coal seam and just drills to the lower limit of the caving zone, and the lower limit of the caving zone is positioned; when the drill rod enters the caving zone with a high rotating speed in the process of drilling the caving zone section, in order to prevent fire caused by an overlarge drilling speed, observing the reading of a water meter of the water injection drilling machine outside a drilling hole, and if the reading of the water meter is stable and normal, indicating that cooling water is continuously pressed in to reduce the temperature of a drill bit part;

secondly, the depth of the drilling hole extends to the upper limit of the caving zone, then the drilling is continued for 10-15m upwards, and the drill rod is withdrawn.

Connecting the special medium-pressure self-expansion type water injection hole packer with a water injection pipe, and conveying the special medium-pressure self-expansion type water injection hole packer connected with the water injection pipe to the hole bottom position of a drilled hole;

and fourthly, testing the water pressure of water injection in the special medium-pressure self-expansion water injection hole packer, radially expanding the tyre bag of the special medium-pressure self-expansion water injection hole packer to outwards press the inner wall of the drilled hole, and observing and recording the change condition of the water pressure gauge in the water injection process until the water pressure gauge is stable.

Fifthly, after the tire bag of the special medium-pressure self-expansion type water injection hole packer is decompressed, the special medium-pressure self-expansion type water injection hole packer is moved downwards by taking 5m as a unit, the water injection pressure test of the step (iv) is repeated for multiple times, and the test is carried out until the test is carried out to the position which is 10m above the lower limit of the theoretically determined fracture zone;

comparing and analyzing the recorded water pressure stability value, wherein the water seepage speed is higher because the crack in the caving zone is better in development and permeability, the pressure relief speed is higher and the water pressure stability value is smaller when the water pressure of the tyre capsule of the medium-pressure self-expanding type hole packer is reduced in the crack zone obviously, and the crack in the crack zone is lower than the fracture zone in non-development permeability, the water pressure reduction is not obvious during the water injection test, namely the pressure relief speed is slow and the water pressure stability value is larger, and the specific position of the upper limit of the caving zone, namely the lower limit of the crack zone is analyzed according to the comparison of the phenomenon;

and seventhly, withdrawing the medium-pressure self-expanding hole packer from the drill hole after the lower limit of the fractured zone, namely the lower limit of the fractured zone, is measured, continuously driving the drill rod to drill upwards by using a water injection drilling machine, continuously drilling for 10-15m after the drill rod is drilled to the theoretical upper limit of the fractured zone, repeating the step (c), and then measuring the upper limit and the lower limit of the fractured zone and the upper limit and the lower limit of the fractured zone after comparative analysis.

The fourth step is carried out by adopting a third mode and comprises the following specific steps:

firstly, using water injection drilling machine to make 1 pair^#Hole and 2^#Drilling holes upwards, 1^#Hole and 2^#After drilling into the goaf, e.g. 1^# Hole water non-return 2^#The upper limit of the falling zone is 1 when the hole returns water^#Hole and 2^#The middle of the height of the final hole position of the hole, in this case for 1^#The hole continues to be drilled, will 1^#Drilling a hole to 10-15m after the upper limit of a theoretical caving zone is reached; when the drill rod enters the caving zone with a high rotating speed in the process of drilling the caving zone section, in order to prevent fire caused by an overlarge drilling speed, observing the reading of a water meter of the water injection drilling machine outside a drilling hole, and if the reading of the water meter is stable and normal, indicating that cooling water is continuously pressed in to reduce the temperature of a drill bit part;

withdrawing the drill rod, connecting the special medium-pressure self-expansion type water injection hole packer with the water injection pipe, and conveying the special medium-pressure self-expansion type water injection hole packer connected with the water injection pipe to the hole bottom position of the drilled hole;

fourthly, after the pressure of the tyre bag of the special medium-pressure self-expansion type water injection hole packer is relieved, the special medium-pressure self-expansion type water injection hole packer is moved downwards by taking 5m as a unit, the water injection water pressure test of the third step is repeated for multiple times, and the test is carried out until the test is carried out to the position which is 10m above the lower limit of the theoretically determined fracture zone;

fifthly, contrastively analyzing the recorded water pressure stability value, wherein the water seepage speed is higher because the crack in the caving zone is better in development permeability, the pressure relief speed is higher and the water pressure stability value is smaller when the water pressure of the tyre capsule of the special medium-pressure self-expanding water injection hole packer is obviously reduced in the crack zone, the crack in the crack zone is lower than the fracture zone in non-development permeability, the water pressure is not obviously reduced in the water injection test, the pressure relief speed is slow, the water pressure stability value is larger, and the specific position of the upper limit of the caving zone, namely the lower limit of the crack zone, is contrastively analyzed according to the phenomenon;

sixthly, using a water injection drilling machine pair 3^#Hole and 4^#Drilling a hole, drill 3^#Hole and 4^#The main purpose of the hole is to detect the upper limit of the fissure zone, 3^#When the hole is drilled to the position above the goaf, the height of the final hole position is 4-6m and 4 m lower than the height of the theoretically determined fractured zone^#When the hole is drilled to the position above the goaf, the height of the final hole position is at the height of the fracture zone determined by theory; 3^#Hole and 4^#Drilling continuously until the hole is drilled to the uppermost part of the goaf, and stopping drilling until the hole is drilled to 10-15m above the theoretical upper limit of a fracture zone;

and seventhly, repeating the step II and the step V, and determining and obtaining the upper limit and the lower limit of the fractured zone and the upper limit and the lower limit of the caving zone after comparison and analysis.

The special medium-pressure self-expansion water injection hole packer comprises a first water injection pipe, a second water injection pipe and a third water injection pipe, wherein the first water injection pipe is sequentially arranged from back to front, a water outlet of the first water injection pipe is connected with a water inlet of the second water injection pipe through a four-way pipe joint, a water injection valve is arranged on the first water injection pipe, the other two interfaces of the four-way pipe joint are respectively connected with a water pressure meter and a water meter, a water outlet of the second water injection pipe is connected with a water inlet of the third water injection pipe through a three-way pipe joint, the other interface of the three-way pipe joint is connected with a pressure release valve, an excircle coaxial line of the water outlet end of the third water injection pipe is provided with a cylindrical tire bladder, the tire bladder corresponds to the third water injection pipe and is provided with a water injection hole communicated with the third water injection pipe, and a water outlet of the third water injection pipe is provided with a constant-pressure drainage device.

The constant pressure drainage device comprises a guide cone, a guide post, a cone sealing plug, a cone sealing sleeve and a spring, wherein the guide cone is of a cone structure with a thin front part and a thick rear part, an annular plate is fixedly arranged at the rear end of the guide cone, the inner circle of the annular plate is fixedly connected with the front end of a third water injection pipe, the outer circle of the cone sealing plug and the inner circle of the cone sealing sleeve are of cone structures with a thick front part and a thin rear part, the outer circle of the cone sealing sleeve and the outer circle of the guide post are of cylinder structures, the outer diameter of the cone sealing sleeve and the outer diameter of the guide post are equal to the inner diameter of the third water injection pipe, the rear end of the guide post is fixedly connected with the front end of the cone sealing plug in a coaxial manner, the cone sealing sleeve is arranged in the third water injection pipe in a coaxial manner and is fixedly connected with the third water injection pipe through a radially arranged countersunk rivet, the guide post is slidably connected in the front end of the third water injection pipe, the front end of the guide cone is open, a support is arranged inside the guide cone, and the front end and the rear end of the spring are respectively connected with the front end face of the support and the guide post in a jacking manner, under the elastic force action of the spring, the excircle of the conical sealing plug is in compression joint and sealing fit with the inner circle of the conical sealing sleeve.

The outer circle of the guide post is provided with an axial water guide groove along the direction parallel to the axis, the front end of the outer circle of the conical sealing plug is provided with an annular water guide groove, and the annular water guide groove is communicated with the rear end of the axial water guide groove.

The supports comprise three crosses which are sequentially arranged from back to front at intervals, the outer ends of the three crosses are fixedly connected with the inner wall of the guide cone, the cross at the foremost side is arranged in the front port of the guide cone, two adjacent cross supports are provided with a supporting rod arranged along the central line direction of the guide cone, and the front end of a spring is connected with the center of the cross at the left back side in a jacking manner; the front end opening of the guide cone is provided with a circular net sheet, and the circular net sheet is connected with the cross frame at the foremost end.

The specific process of testing the water pressure of water injection into the special medium-pressure self-expanding water injection hole packer comprises the following steps:

opening a water injection valve, allowing medium-pressure water to enter a third water injection pipe along a first water injection pipe and a second water injection pipe, sealing a water outlet of the third water injection pipe by a constant-pressure drainage device arranged at the front port of the third water injection pipe, allowing the medium-pressure water to enter a tire bladder from a water injection hole, expanding the tire bladder, pressing the outer circle of the tire bladder and the inner wall of a drill hole to seal the drill hole, allowing pressure water in the third water injection pipe to be pressed forwards against the rear end face of a conical sealing plug, and when the water pressure does not exceed the rated sealing pressure of the constant-pressure drainage device, the outer circle of the conical sealing plug is always in sealed connection with the inner circle of the conical sealing sleeve, and when the water pressure of water injection is greater than the rated sealing pressure of the constant-pressure drainage device, the pressure water in the third water injection pipe pushes the conical sealing plug and a guide column to move forwards, a spring is compressed, a conical gap is formed between the outer circle of the conical sealing plug and the conical sealing sleeve, and the pressure water flows into the guide cone guide cylinder through the conical gap, an annular water guide groove and an axial water guide groove, then the water is discharged into the drill hole from the front end opening of the guide cone cylinder, the indication number of a water pressure meter and a water gauge is observed and recorded in the water injection process, and the larger the water pressure is, the larger the conical gap is, and the higher the pressure relief water flow speed is;

when the water outlet at the front end of the guide cone cylinder is positioned in a bent sunken zone, because the bent sunken zone has no crack and negative pressure, and the pressure relief speed is consistent with the water injection speed, the pressure relief pressure is kept unchanged as the water injection pressure, and the pressure kept after the water injection pressure and the pressure relief pressure reach dynamic balance is larger than the pressure kept in the crack zone; constantly observing a water meter, observing whether the water inflow is stable, recording the numerical value of the water pressure meter at the moment, closing a water injection control valve, keeping the tyre bag in an expansion state at the moment, and sealing the conical sealing plug and the conical sealing sleeve in a compression joint mode without water outflow and pressure relief; and (3) because the tyre bag needs to be withdrawn to the orifice for continuous measurement, the pressure relief treatment needs to be carried out on the water pressure in the tyre bag, a pressure relief valve on a three-way pipe joint is opened, the water pressure in the tyre bag is relieved, the tyre bag retracts to the original unexpanded state after the pressure relief, the whole special medium-pressure self-expanding water injection hole packer is withdrawn, and the operation is repeated after the tyre bag is withdrawn to the specified position to record the water pressure and water meter data.

By adopting the technical scheme, from the aspects of no influence on working face production, convenient observation operation and safety, the priority of the three modes of observing drilling and hole distribution by water injection on site is the first mode, the second mode and the third mode.

The concentration of gas in caving zones of high gas mines and outburst mines is high, and the gaps between broken rock masses and rock masses in caving zones cause that cooling water used as measures for flushing dust and cooling cannot return during drilling, so that a driller cannot master whether the cooling water is normally supplied or not, and once frictional heat between a water-cut drill bit and the rock is very easy to ignite to detonate the gas in the goaf. The invention designs that a water meter is arranged on a water supply pipeline of a water injection drilling machine, whether water supply is normal or not is judged according to the numerical value change of the water meter during drilling, the drilling is immediately stopped when the water supply is stopped, accidents are prevented, and safe construction of gas drilling in a goaf by preventing ignition and detonation in a caving zone is realized.

Observing drill holes by utilizing a bent subsidence zone above a mining coal bed and a same-layer roadway arrangement of the bent subsidence zone, wherein the initial position is in the bent subsidence zone during drilling construction, and the cooling water return condition is normal; and the drilling hole enters a fracture zone along with the increase of the length of the drilling hole, but the water return quantity is reduced, then the drilling hole continues to enter an overflow zone, and the water return quantity of the cooling water is obviously and seriously reduced until the water return is stopped. Therefore, the development heights and the zonal positions of the caving zone, the crack zone and the bending subsidence zone are judged according to the water return condition of the drilling cooling water.

According to the mine water supply pressure and the performance of a drilling machine, selecting a water injection hole packer with appropriate water injection pressure and geometric dimension, wherein the water injection hole packer can freely move in an observation drill hole as required, measuring the water injection pressure of each layer in a fracture zone and an overflow zone, calculating the water injection pressure change according to stable water pressure (MPa), determining the rapid pressure value in a water injection pipe, further calculating the water injection quantity by applying a Bernoulli equation, determining the layer where the hole packer can be located, and achieving the purpose of accurately measuring the height of the fracture zone and the development degree of the fracture.

The special medium-pressure self-expansion water injection hole packer can realize medium-pressure hole sealing and high-pressure water injection, pressure water is injected into a tire bag to realize expansion of the tire bag, a drill hole is sealed after the tire bag expands, the pressure water is decompressed and drained into the drill hole through the guide cone cylinder after the water pressure reaches the rated sealing pressure (namely the maximum elastic force of the spring) of the constant-pressure drainage device, and water injection operation is carried out while hole sealing is carried out. The guide cone not only plays a role in guiding the drill hole to the bottom of the drill hole in the moving process, but also provides a supporting and connecting role for the spring. The cross frames are arranged in the guide cone barrel, the guide cone barrel is supported, and the adjacent cross frames are connected through the supporting rod, so that the cross frame on the last side is stable and does not deform under the action of the elastic force of the spring. The round net piece is arranged at the front end opening of the guide conical cylinder, so that granular sundries in the drill holes are prevented from entering the guide conical cylinder to influence the normal work of the spring. Under the action of a spring and water pressure, the guide column moves back and forth in the third water injection pipe, the outer circle of the conical sealing plug and the inner circle of the conical sealing sleeve are in compression joint sealing, the sealing performance is good, and the conical sealing sleeve and the third water injection pipe are fixed through the countersunk head rivet, so that the sealing reliability is ensured. The annular water guide groove and the axial water guide groove play roles in overflowing and guiding flow. The fixed cover of child bag is established on the excircle of third water injection pipe front end outlet, and when the child bag was not expanded in addition, the annular plate external diameter was greater than or equal to child bag external diameter, and the child bag front end contacts with the annular plate, can avoid like this when moving in the drilling, and the contact of debris in child bag front end and the drilling is protected the child bag not to be damaged.

The working face of the stope of the high gas mine and the coal and gas outburst mine is easy to cause the return air flow of the working face and the gas at the upper corner to exceed the limit due to the large gas emission amount, thereby forming potential safety hazards. In order to prevent the gas concentration from exceeding the limit, the high-position drilling extraction technology of the fracture zone of the coal seam roof is generally adopted at present. The mechanism is that the caving zone, the fissure zone and the bending subsidence zone formed on the top plate of the goaf by the stoping face are different in space height and permeability, the ventilation gas degree of the stoping face and the upper corner is different, and the extraction drill holes are arranged at the proper positions of the fissure zone with developed fissures, so that a large amount of high-concentration gas is extracted, and the purpose of preventing the gas from exceeding the limit is achieved. Therefore, the position of the coal seam roof fracture zone, namely the vertical height from the coal seam, needs to be accurately measured, and a construction roof fracture zone extraction borehole is designed according to the measurement result. The invention provides a fracture zone height measuring method and process based on roof fracture zone characteristics, and the method and process are scientific in principle, perfect in theory, reliable in measuring result, strong in practicability, simple to operate, universal and universal in using instruments and devices, and mainly solve the problems that the caving zone and the fracture zone height in mine gas extraction are difficult to determine.

Drawings

FIG. 1 is a schematic sectional view of a first hole distribution mode for on-site water injection observation in the present invention;

FIG. 2 is a schematic cross-sectional view of a second method of observing water injection in situ for drilling and hole distribution;

FIG. 3 is a schematic cross-sectional view of a third method for observing water injection in situ and drilling holes;

FIG. 4 is a schematic structural diagram of the special medium-pressure self-expanding water injection hole packer in the invention;

fig. 5 is an enlarged view of the third fill tube front port bladder and the constant pressure drain of fig. 4.

Detailed Description

The invention discloses a method for accurately measuring the position of a coal seam roof fissure zone based on medium-pressure water injection, which comprises the following steps of:

the empirical formulas include a calculation formula for the height of the falling zone (as shown in Table 1) and a calculation formula for the height of the fractured zone (as shown in Table 2)

Note: sigma M-is accumulated thickness mining, the single-layer thickness mining is 1-3, the accumulated thickness mining is not more than 15M, and plus or minus term is a medium error.

the first mode is that under the condition that a tunnel is arranged above a coal seam roof, namely in a curved sunken zone, a proper place is selected from the tunnel at the upper part of the curved sunken zone; designing a drilling angle and a drilling depth according to the height of the fracture zone determined by the theory of the second step, and drilling a lower goaf in a pressurized water drilling mode as shown in the attached drawing 1; the height of the curved subsidence zone from the central line of the upper roadway to the coal bed below is X, the maximum angle at which a drilling machine can drill a downward drill hole is alpha, and the height of the caving zone determined by theory is H₁The height of the fissure zone determined by theory is H₂Based on the above data, the hole depth (X-H) of the position of the opening from the upper limit of the caving zone, i.e., the lower limit of the fractured zone, is obtained₁) A/cos alpha, the depth of the hole from the position of the opening to the upper limit of the fractured zone is (X-H)₁-H₂）/cosα；

The second mode is that under the condition that a roadway is arranged at the lower part of the coal seam floor, a proper place is selected to drill a hole in the inclined upward direction in the roadway at the lower part of the goaf, namely the bottom suction roadway; drilling an upward goaf by a pressurized water drilling mode according to the drilling angle and the drilling depth designed according to the height of the fracture zone determined by the theory of the second step as shown in the attached drawing 2: the height of the bottom suction roadway from the coal seam is X, the drilling machine can drill the maximum angle alpha of the upward drilling hole, and the height of the caving zone obtained by theoretical determinationIs H₁The height of the fissure zone determined theoretically is H₂According to the data, the hole depth (X + H) of the position of the open hole from the upper limit of the caving zone, namely the lower limit of the fractured zone is obtained₁) Sin alpha, the depth of the hole from the position of the hole to the upper limit of the fissure zone is (X + H)₁+H₂）/sinα；

The third mode is that under the condition that no laneway exists above the coal seam roof, namely in the bent subsidence zone and at the lower part of the coal seam floor, a proper place is selected to drill a hole obliquely upwards in the laneway adjacent to the goaf; designing a drilling angle and a drilling depth according to the height of the fractured zone and the distance from the drilling field to the goaf theoretically determined in the second step, and drilling the goaf close to the goaf in a pressurized water drilling mode as shown in the attached drawing 3: the horizontal distance between the lower wall of the roadway close to the goaf and the upper wall of the goaf of the working face is X, and the height of the caving zone determined theoretically is H₁The height of the fissure zone determined theoretically is H₂And obtaining the angle during drilling design according to the data, wherein the maximum elevation angle of the lower limit of a drill site and an caving zone, namely a fracture zone in the roadway adjacent to the goaf is alpha = arctan (H)₁/X), the maximum elevation angle of the upper limit of a drilling field and a fracture zone, namely the lower limit of a bending subsidence zone is beta = arctan [ (H)₁+H₂)/X]Four boreholes were designed: 1^#The hole angle is alpha/2, 2^#The hole angle is alpha, 3^#The hole angle is (beta + alpha)/2, 4^#The hole angle is beta.

As shown in fig. 1, the fourth step performed in the first manner includes the following specific steps:

As shown in fig. 2, the fourth step performed in the second manner includes the following specific steps:

As shown in fig. 3, the fourth step performed by the third method specifically includes:

firstly, using water injection drilling machine to make 1 pair^#Hole and 2^#Drilling holes upwards, 1^#Hole and 2^#After drilling into the goaf, e.g. 1^#Hole water non-return 2^#The upper limit of the falling zone is 1 when the hole returns water^#Hole and 2^#The middle of the height of the final hole position of the hole, in this case for 1^#The hole continues to be drilled, will 1^#Hole drillingDrilling for 10-15m after reaching the upper limit of the theoretical caving zone; when the drill rod enters the caving zone with a high rotating speed in the process of drilling the caving zone section, in order to prevent fire caused by an overlarge drilling speed, observing the reading of a water meter of the water injection drilling machine outside a drilling hole, and if the reading of the water meter is stable and normal, indicating that cooling water is continuously pressed in to reduce the temperature of a drill bit part;

As shown in fig. 4 and 5, the special medium-pressure self-expanding water injection hole packer comprises a first water injection pipe 4, a second water injection pipe 5 and a third water injection pipe 6 which are sequentially arranged from back to front, a water outlet of the first water injection pipe 4 is connected with a water inlet of the second water injection pipe 5 through a four-way pipe joint 7, a water injection valve 27 is arranged on the first water injection pipe 4, the other two interfaces of the four-way pipe joint 7 are respectively connected with a water pressure meter 8 and a water pressure meter 9, a water outlet of the second water injection pipe 5 is connected with a water inlet of the third water injection pipe 6 through a three-way pipe joint 10, the other interface of the three-way pipe joint 10 is connected with a pressure release valve 11, a cylindrical tire bladder 12 is coaxially arranged at the outer circle of the water outlet end of the third water injection pipe 6, communicated water injection holes 13 are correspondingly arranged on the tire bladder 12 and the third water injection pipe 6, and a constant-pressure water discharge device 14 is arranged at the water outlet of the third water injection pipe 6.

The constant pressure drainage device 14 comprises a guide cone cylinder 15, a guide column 16, a conical sealing plug 17, a conical sealing sleeve 18 and a spring 19, wherein the guide cone cylinder 15 is of a conical cylinder structure with a thin front part and a thick rear part, the rear end of the guide cone cylinder 15 is fixedly provided with an annular plate 20, the inner circle of the annular plate 20 is fixedly connected with the front end of a third water injection pipe 6, the outer circle of the conical sealing plug 17 and the inner circle of the conical sealing sleeve 18 are of conical structures with a thick front part and a thin rear part, the outer circle of the conical sealing sleeve 18 and the outer circle of the guide column 16 are of cylindrical structures, the outer diameter of the conical sealing sleeve 18, the outer diameter of the guide column 16 and the inner diameter of the third water injection pipe 6 are equal, the rear end of the guide column 16 is fixedly connected with the front end of the conical sealing plug 17 in a coaxial manner, the conical sealing sleeve 18 is arranged in the third water injection pipe 6 and is fixedly connected with the third water injection pipe 6 through a radially arranged countersunk rivet 21, the guide column 16 is slidably connected in the front end of the third water injection pipe 6, the front end of the guide cone cylinder 15 is open, a support is arranged inside the guide cone cylinder 15, the front end and the rear end of the spring 19 are respectively connected with the support and the front end face of the guide column 16 in a jacking mode, and under the elastic action of the spring 19, the outer circle of the conical sealing plug 17 is in compression joint and sealing fit with the inner circle of the conical sealing sleeve 18.

An axial water chute 22 is arranged on the outer circle of the guide column 16 along the direction parallel to the axis, an annular water chute 23 is arranged at the front end of the outer circle of the conical sealing plug 17, and the annular water chute 23 is communicated with the rear end of the axial water chute 22.

The supports comprise three crosses 24 which are sequentially arranged from back to front at intervals, the outer ends of the three crosses 24 are fixedly connected with the inner wall of the guide cone 15, the cross 24 at the foremost side is arranged in the front end of the guide cone 15, two adjacent crosses 24 are provided with a support rod 25 which is arranged along the central line direction of the guide cone 15, and the front end of the spring 19 is connected with the center of the cross 24 at the left back side in a jacking manner; the front end of the guide cone 15 is provided with a circular net 26, and the circular net 26 is connected with the cross 24 at the most front end.

the inlet end of the first water delivery pipe 4 is connected with a water injection pump, a water injection valve 27 is opened, medium-pressure water enters the third water injection pipe 6 along the first water injection pipe 4 and the second water injection pipe 5, a constant-pressure water discharging device 14 arranged at the front port of the third water injection pipe 6 seals the water outlet of the third water injection pipe 6, the medium-pressure water enters the tire bladder 12 from the water injection hole 13, the tire bladder 12 expands, the outer circle of the tire bladder 12 is in compression joint with the inner wall of a drilled hole to seal the drilled hole, the pressure water in the third water injection pipe 6 is pressed forwards against the rear end face of the conical sealing plug 17, when the water pressure does not exceed the rated sealing pressure of the constant-pressure water discharging device 14, the outer circle of the conical sealing plug 17 is always in sealing connection with the inner circle of the conical sealing sleeve 18, when the water pressure of the water injection is greater than the rated sealing pressure of the constant-pressure water discharging device 14, the pressure water in the third water injection pipe 6 pushes the conical sealing plug 17 and the guide column 16 to move forwards, and the spring 19 is compressed, a conical gap is formed between the outer circle of the conical sealing plug 17 and the inner circle of the conical sealing sleeve 18, pressure water flows into the guide cone cylinder 15 through the conical gap, the annular water guide groove 23 and the axial water guide groove 22 and is discharged into a drill hole from the front end port of the guide cone cylinder 15, the readings of the water pressure gauge 8 and the water gauge 9 are observed and recorded in the water injection process, and the larger the water pressure is, the larger the conical gap is, the higher the pressure-relief water flow speed is;

when the water outlet at the front end of the guide cone cylinder 15 is positioned in a curved sunken zone, because the cracks of the curved sunken zone do not develop and have negative pressure, and the pressure relief speed is consistent with the water injection speed, the pressure relief pressure is kept unchanged as the water injection pressure, and the pressure kept after the water injection pressure and the pressure relief pressure reach dynamic balance is larger than the pressure kept in the crack zone; constantly observing a water meter 9, judging whether enough water inflow is kept or not, recording the numerical value of the water meter 8 at the moment, closing a water injection control valve, keeping the tire bag 12 in the maximum expanded state at the moment, and sealing a conical sealing plug 17 and a conical sealing sleeve 18 in a compression joint mode without water outflow and pressure relief; and (3) because the tyre needs to be withdrawn to the orifice for continuous measurement, the pressure relief treatment needs to be carried out on the water pressure in the tyre bag 12, the pressure relief valve 11 on the three-way pipe joint 10 is opened, the water pressure in the tyre bag 12 is relieved, the tyre bag 12 retracts to the original unexpanded state after the pressure relief, the whole special medium-pressure self-expanding water injection hole packer is withdrawn, and the operation is repeated after the tyre bag is withdrawn to the specified position to record the data of the water pressure meter 8 and the water pressure meter 9.

The following is the actual measurement situation of the technology applied to the field:

the method is implemented and applied to the 202 working face of Shaanxi rich source coal industry, namely party river coal mine, and the implementation overview is as follows: when the coal seam of the party river coal mine No. 2 is thin and no laneway is arranged above and below the working face 202, drilling is carried out by adopting a hole arrangement mode of a third site water injection observation drilling hole arrangement mode (refer to the attached figure 3). The method comprises the following specific steps:

(1) the lithology of the roof of the 202 working surface is sandy mudstone, and the estimated heights of the caving zone and the fractured zone are calculated through theoretical analysis and selection of a proper empirical formula as follows:

height of the falling zone:

height of fissure zone:

(2) the numerical simulation results in a fissure zone height of 22 m. And because the distance between the gate way on the 202 working face close to the roadway, namely 204, and the goaf is 40m, the following steps are carried out:

the maximum elevation angle of the drill site and the lower limit of the fracture zone is as follows:

the maximum elevation angle of the upper limit of the drill site and the fractured zone is as follows:

(3) and (3) designing the following three groups of four drilling components A, B, C according to the drilling angle data obtained in the steps (1) and (2) for downhole measurement:

B. the C groups of drilling holes are arranged at positions 28m and 26m away from the south of the crossheading communication roadway on the 204 respectively. 3^#And 4^#The depth and inclination angle of the holes are consistent with those of the group A, 1^#And 2^#The hole can be finely adjusted according to the construction effect, if 1^#Hole return water, 2^#Hole without returning water, pair 1^#The angle of the hole is adjusted up to 1 degree, and the angle is 2 degrees^#The wells were down-regulated by 1. The lower caving zone limit is further determined at B, C.

(4) The design angle of the drill hole obtained according to the step (3) passes through three pairs of groups 1^#And 2^#The following results were obtained from downhole measurements as shown in the following table:

the analysis of the data shows that the lower limit height of the fracture zone at the top of the working surface of a certain coal mine 202 in Shaanxi is 12.6 m.

(5) For the measurement of the upper limit of the fracture zone, the construction is carried out to the designed hole depth, the drilling is stopped, the drill rod is withdrawn, the tyre capsule 12 of the special medium-pressure self-expansion type water injection hole packer connected with high-pressure water is pushed into the position 10m away from the final hole, the first water injection pipe 4 is connected with a water pressure meter, and the specific water injection pressure is determined according to underground equipment. In the water injection process, a water pressure meter is constantly watched, if the water injection pressure is reduced, the fact that the position 10m, away from the final hole, of the tyre bag 12 is located in a fractured zone is indicated, the water injection valve 27 is closed, the position, away from the final hole, of the tyre bag 12 is retracted, if the water injection pressure is always in a reduced state, the final hole of the 3# hole is located in the fractured zone, the 4# hole needs to be constructed, if the water injection pressure of the 3# hole is unchanged, the fact that the position 10m, away from the final hole, of the water injection hole packer is located in a bent sunken zone is indicated, the 4# hole does not need to be constructed, the water injection valve 27 is closed, the water injection hole packer is retreated to the position 20m, away from the final hole, the water injection valve 27 is opened, if the water pressure is stable, the water injection hole packer is retreated repeatedly, and if the water pressure is reduced, the water injection valve 27 is closed, the position, away from the tyre bag 12 is retracted to the final hole until the minimum error value is found.

(6) And (5) recording construction data according to the construction steps in the step (5), wherein the obtained data are as follows:

the upper limit height of the fracture zone at the top of the working surface of the Shaanxi Dang river coal mine 202 is 25m according to the analysis of the data.

The present embodiment is not intended to limit the shape, material, structure, etc. of the present invention in any way, and any simple modification, equivalent change and modification made to the above embodiments according to the technical spirit of the present invention are within the scope of the technical solution of the present invention.

Claims

1. The method for accurately measuring the position of the coal seam roof fissure zone based on medium-pressure water injection is characterized by comprising the following steps of: the method comprises the following steps:

2. The method for accurately determining the position of the coal seam roof fissure zone based on medium-pressure water injection according to claim 1, characterized by comprising the following steps: three hole distribution modes for on-site water injection observation drilling are designed in the third step:

The second mode is that under the condition that a roadway is arranged at the lower part of the coal seam floor, a proper place is selected to drill a hole in the inclined upward direction in the roadway at the lower part of the goaf, namely the bottom suction roadway; designing a drilling angle according to the height of the fractured zone determined by the theory of the second step andthe hole depth adopts the pressurized-water to beat the mode of boring to the goaf to beat and bore: the height of the bottom suction roadway from the coal seam is X, the drilling machine can drill the maximum angle alpha of the upward drill hole, and the height of the caving zone determined theoretically is H₁The height of the fissure zone determined theoretically is H₂According to the data, the hole depth (X + H) of the position of the open hole from the upper limit of the caving zone, namely the lower limit of the fractured zone is obtained₁) Sin alpha, the depth of the hole from the position of the hole to the upper limit of the fissure zone is (X + H)₁+H₂）/sinα；

The third mode is that under the condition that no laneway exists above the coal seam roof, namely in the bent subsidence zone and at the lower part of the coal seam floor, a proper place is selected to drill a hole obliquely upwards in the laneway adjacent to the goaf; designing a drilling angle and a hole depth according to the height of the fractured zone and the distance from the drilling field to the goaf theoretically determined in the second step, and drilling the goaf by adopting a pressurized water drilling mode: the horizontal distance between the lower wall of the roadway close to the goaf and the upper wall of the goaf of the working face is X, and the height of the caving zone determined theoretically is H₁The height of the fissure zone determined theoretically is H₂And obtaining the angle during drilling design according to the data, wherein the maximum elevation angle of the lower limit of a drill site and an caving zone, namely a fracture zone in the roadway adjacent to the goaf is alpha = arctan (H)₁/X), the maximum elevation angle of the upper limit of a drilling field and a fracture zone, namely the lower limit of a bending subsidence zone is beta = arctan [ (H)₁+H₂)/X]Four boreholes were designed: 1^#The hole angle is alpha/2, 2^#The hole angle is alpha, 3^#The hole angle is (beta + alpha)/2, 4^#The hole angle is beta.

3. The method for accurately determining the position of the coal seam roof fissure zone based on medium-pressure water injection is characterized by comprising the following steps of: the fourth step is carried out in a first mode, and comprises the following specific steps:

4. The method for accurately determining the position of the coal seam roof fissure zone based on medium-pressure water injection is characterized by comprising the following steps of: the fourth step is carried out in a second mode, and the specific steps are as follows:

secondly, after the depth of the drilling hole extends to the upper limit of the caving zone, the drilling hole continues to drill for 10-15m upwards, and the drill rod is withdrawn;

fourthly, testing the water pressure of water injection in the special medium-pressure self-expansion water injection hole packer, radially expanding a tire bag of the special medium-pressure self-expansion water injection hole packer to outwards press the inner wall of the drilled hole, and constantly observing and recording the change condition of the water pressure gauge in the water injection process until the water pressure gauge is stable;

5. The method for accurately determining the position of the coal seam roof fissure zone based on medium-pressure water injection is characterized by comprising the following steps of: the fourth step is carried out by adopting a third mode and comprises the following specific steps:

firstly, using water injection drilling machine to make 1 pair^#Hole and 2^#Drilling holes upwards, 1^#Hole and 2^#After drilling into the goaf, e.g. 1^#Hole water non-return 2^#The upper limit of the falling zone is 1 when the hole returns water^#Hole and 2^#The middle of the height of the final hole position of the hole, in this case for 1^#The hole continues to be drilled, will 1^#Drilling a hole to 10-15m after the upper limit of a theoretical caving zone is reached; when the drill rod enters the caving zone with a high rotating speed in the process of drilling the caving zone section, in order to prevent fire caused by an overlarge drilling speed, observing the reading of a water meter of the water injection drilling machine outside a drilling hole, and if the reading of the water meter is stable and normal, indicating that cooling water is continuously pressed in to reduce the temperature of a drill bit part;

6. The method for accurately determining the position of the coal seam roof fissure zone based on medium-pressure water injection according to claim 3, 4 or 5, wherein the method comprises the following steps: the special medium-pressure self-expansion water injection hole packer comprises a first water injection pipe, a second water injection pipe and a third water injection pipe, wherein the first water injection pipe is sequentially arranged from back to front, a water outlet of the first water injection pipe is connected with a water inlet of the second water injection pipe through a four-way pipe joint, a water injection valve is arranged on the first water injection pipe, the other two interfaces of the four-way pipe joint are respectively connected with a water pressure meter and a water meter, a water outlet of the second water injection pipe is connected with a water inlet of the third water injection pipe through a three-way pipe joint, the other interface of the three-way pipe joint is connected with a pressure release valve, an excircle coaxial line of the water outlet end of the third water injection pipe is provided with a cylindrical tire bladder, the tire bladder corresponds to the third water injection pipe and is provided with a water injection hole communicated with the third water injection pipe, and a water outlet of the third water injection pipe is provided with a constant-pressure drainage device.

7. The method for accurately determining the position of the coal seam roof fissure zone based on medium-pressure water injection according to claim 6, wherein the method comprises the following steps: the constant pressure drainage device comprises a guide cone, a guide post, a cone sealing plug, a cone sealing sleeve and a spring, wherein the guide cone is of a cone structure with a thin front part and a thick rear part, an annular plate is fixedly arranged at the rear end of the guide cone, the inner circle of the annular plate is fixedly connected with the front end of a third water injection pipe, the outer circle of the cone sealing plug and the inner circle of the cone sealing sleeve are of cone structures with a thick front part and a thin rear part, the outer circle of the cone sealing sleeve and the outer circle of the guide post are of cylinder structures, the outer diameter of the cone sealing sleeve and the outer diameter of the guide post are equal to the inner diameter of the third water injection pipe, the rear end of the guide post is fixedly connected with the front end of the cone sealing plug in a coaxial manner, the cone sealing sleeve is arranged in the third water injection pipe in a coaxial manner and is fixedly connected with the third water injection pipe through a radially arranged countersunk rivet, the guide post is slidably connected in the front end of the third water injection pipe, the front end of the guide cone is open, a support is arranged inside the guide cone, and the front end and the rear end of the spring are respectively connected with the front end face of the support and the guide post in a jacking manner, under the elastic force action of the spring, the excircle of the conical sealing plug is in compression joint and sealing fit with the inner circle of the conical sealing sleeve.

8. The method for accurately determining the position of the coal seam roof fissure zone based on medium-pressure water injection is characterized by comprising the following steps of: the outer circle of the guide post is provided with an axial water guide groove along the direction parallel to the axis, the front end of the outer circle of the conical sealing plug is provided with an annular water guide groove, and the annular water guide groove is communicated with the rear end of the axial water guide groove.

9. The method for accurately determining the position of the coal seam roof fissure zone based on medium-pressure water injection is characterized by comprising the following steps of: the supports comprise three crosses which are sequentially arranged from back to front at intervals, the outer ends of the three crosses are fixedly connected with the inner wall of the guide cone, the cross at the foremost side is arranged in the front port of the guide cone, two adjacent cross supports are provided with a supporting rod arranged along the central line direction of the guide cone, and the front end of a spring is connected with the center of the cross at the left back side in a jacking manner; the front end opening of the guide cone is provided with a circular net sheet, and the circular net sheet is connected with the cross frame at the foremost end.

10. The method for accurately determining the position of the coal seam roof fissure zone based on medium-pressure water injection is characterized by comprising the following steps of: the specific process of testing the water pressure of water injection into the special medium-pressure self-expanding water injection hole packer comprises the following steps: