CN117052344A - Leakage blocking drilling method for goaf of close-range coal seam group - Google Patents
Leakage blocking drilling method for goaf of close-range coal seam group Download PDFInfo
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- 238000005553 drilling Methods 0.000 title claims abstract description 236
- 238000000034 method Methods 0.000 title claims abstract description 97
- 239000003245 coal Substances 0.000 title claims abstract description 62
- 230000000903 blocking effect Effects 0.000 title description 2
- 239000002002 slurry Substances 0.000 claims abstract description 339
- 239000011435 rock Substances 0.000 claims abstract description 96
- 230000008569 process Effects 0.000 claims abstract description 40
- 238000012360 testing method Methods 0.000 claims abstract description 27
- 239000007788 liquid Substances 0.000 claims abstract description 23
- 238000002347 injection Methods 0.000 claims description 165
- 239000007924 injection Substances 0.000 claims description 165
- 239000002245 particle Substances 0.000 claims description 20
- 239000007921 spray Substances 0.000 claims description 20
- 230000001276 controlling effect Effects 0.000 claims description 19
- 229910000278 bentonite Inorganic materials 0.000 claims description 18
- 239000000440 bentonite Substances 0.000 claims description 18
- SVPXDRXYRYOSEX-UHFFFAOYSA-N bentoquatam Chemical compound O.O=[Si]=O.O=[Al]O[Al]=O SVPXDRXYRYOSEX-UHFFFAOYSA-N 0.000 claims description 18
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- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 description 2
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Classifications
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B33/00—Sealing or packing boreholes or wells
- E21B33/10—Sealing or packing boreholes or wells in the borehole
- E21B33/13—Methods or devices for cementing, for plugging holes, crevices or the like
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B10/00—Drill bits
- E21B10/46—Drill bits characterised by wear resisting parts, e.g. diamond inserts
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B10/00—Drill bits
- E21B10/60—Drill bits characterised by conduits or nozzles for drilling fluids
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B7/00—Special methods or apparatus for drilling
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/10—Geothermal energy
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- Fluid Mechanics (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Mechanical Engineering (AREA)
- Consolidation Of Soil By Introduction Of Solidifying Substances Into Soil (AREA)
Abstract
The invention provides a near-distance coal seam group goaf plugging drilling method, which is used for determining the surrounding rock disturbance influence range of the wall of a drilled hole based on a loose circle theory; determining the diameter of a spraying nozzle, the concentration of the slurry, the granularity of the slurry, the pump pressure of the grouting pump and the consumption of the slurry corresponding to the slurry spraying in the drilling hole through a slurry spraying test, so that the spraying range of the slurry reaches the influence range of surrounding rock disturbance of the hole wall; preparing slurry according to a test result, adjusting the pressure of a grouting pump, and arranging a jet nozzle with a special jet nozzle diameter on a drill bit; in the drilling process by using a drill bit, the grouting pump capable of adjusting grouting pressure is used for controlling the grouting liquid to be sprayed into the goaf and the broken rock body through the spraying nozzle, so that a stable space is formed, and then the process of passing through the goaf by a high-pressure grouting spraying method is realized. According to the invention, the jet nozzle is arranged at the upper part of the drill bit, so that the slurry waiting for drilling operation and the rock mass solidification at the periphery of the drilled hole are realized in a high-pressure jet mode to form a cementing body, and the geological drilling time and cost of the goaf are saved.
Description
Technical Field
The invention relates to the technical field of goaf management, in particular to a method for plugging and drilling goafs of a close-range coal seam group.
Background
After the underground coal mine is mined, the upper rock stratum is gradually bent and deformed, when the strength limit is reached, the upper rock stratum is broken and collapsed into a goaf, and the upper rock stratum is vertically divided into collapse zones with irregularly arranged rock blocks, crack zones with developed pore cracks and bending sinking zones mainly including bending sinking, namely three zones. In the process of coal mine goaf investigation, mobile deformation monitoring and lower part unstable space grouting treatment, geological drilling is required to be carried out on three zones.
The most common technical means at present mainly comprise two types: cement grouting solidification is carried out on broken rock in the goaf, so that a layer of complete rock is formed by transformation, and then drilling is carried out in slurry-rock concretes; the other is a drilling technology for protecting the hole wall by a rigid sleeve in the broken rock body, preventing broken rock on the surface of the hole wall from falling off and realizing the sleeve protection condition of the broken rock body.
For the first type of grouting method goaf drilling technology, large-scale grouting reinforcement is needed in the goaf, drilling is needed after slurry solidification is waited, the grouting area is large, the grouting waiting time is long, and the geological drilling cost and time are high.
For the second type of casing drilling technology, the casing series is required to be designed in advance, if the casing series is not designed sufficiently, the technology cannot drill to the designed horizon, so that the goaf drill hole is invalid, the technology is complex, and the drilling process is long.
Thus, the geological drilling technology of the goaf three zones still needs to be solved.
Disclosure of Invention
The invention provides a plugging drilling method for goafs of a close-range coal seam group, which is used for solving the defects of high construction cost and long time for geological drilling of three zones of the goafs in the prior art and realizing a goaf safe drilling technology which is simple and feasible, has high operability and can realize occurrence of multiple coal seam goafs and different pores.
The invention provides a plugging drilling method for goafs of a close-range coal seam group, which comprises the following steps:
determining the surrounding rock disturbance influence range of the hole wall of the drill hole based on a loosening ring theory;
determining the diameter of an injection nozzle, the concentration of the slurry, the granularity of the slurry, the pressure of a grouting pump and the consumption of the slurry corresponding to the slurry injection in the drilling hole through a slurry injection test, so that the injection range of the slurry reaches the surrounding rock disturbance influence range of the wall of the drilling hole, and the pressure of the grouting pump is larger than a preset threshold;
Preparing the slurry according to the slurry concentration, the slurry granularity and the slurry consumption, manufacturing a jet nozzle with the diameter of the jet nozzle, installing the jet nozzle on a drill bit, and adjusting a grouting pump according to the pressure of the grouting pump;
the slurry is controlled to be injected through the injection nozzle by the grouting pump with adjustable grouting pressure during the drilling of the borehole by using the drill bit.
According to the near-distance coal seam group goaf plugging drilling method provided by the invention, the determination of the diameter of the injection nozzle, the concentration of the slurry, the granularity of the slurry, the pressure of the grouting pump and the consumption of the slurry corresponding to the slurry injection in the drill hole through the slurry injection test comprises the following steps:
and (3) performing a slurry injection test under the geological environment where the drilling hole is located, and determining the injection pump pressure and the slurry consumption required by the injection range of the slurry reaching the surrounding rock disturbance influence range of the wall of the drilling hole under the conditions of different injection nozzle diameters, different slurry concentrations and different slurry granularity.
According to the near-distance coal seam group goaf plugging drilling method provided by the invention, the slurry is configured according to the slurry concentration, the slurry granularity and the slurry consumption, the injection nozzle with the diameter of the injection nozzle is manufactured and arranged on a drill bit, and the grouting pump is adjusted according to the pressure of the grouting pump, and the method comprises the following steps:
Selecting a set of data from a plurality of sets of data obtained by the slurry injection test, each set of data including injection nozzle diameter, slurry concentration, slurry particle size, grouting pump pressure and slurry consumption, in the case that the current drilling position of the borehole is a fracture zone of the current goaf;
configuring the slurry according to the selected set of data, installing a jet nozzle on the drill bit, and adjusting a grouting pump pressure of the grouting pump;
selecting another set of data from the sets of data obtained by the slurry injection test under the condition that the current drilling position of the drilling hole is the caving zone of the current goaf;
configuring the slurry according to the selected other set of data, installing a jet nozzle on the drill bit, and adjusting the grouting pump pressure of the grouting pump;
wherein the pump pressure of the slurry in the set of data is greater than the pump pressure of the slurry in the other set of data, the slurry concentration in the set of data is less than the slurry concentration in the other set of data, and the slurry particle size in the set of data is less than the slurry particle size in the other set of data.
According to the near-distance coal seam group goaf plugging drilling method provided by the invention, the grouting pump is adjusted according to the pressure of the grouting pump, and the method comprises the following steps:
Under the condition that the current drilling position of the drill hole is a fracture zone of a current goaf, performing multiple slurry injections at the current drilling position, wherein the pressure of a grouting pump used for the first slurry injection in the multiple slurry injections is larger than or equal to that of the grouting pump in the group of data, the pressure of the grouting pump used for the multiple slurry injections is gradually reduced, and the injection time is gradually prolonged;
and under the condition that the current drilling position of the drill hole is the collapse zone of the current goaf, performing multiple slurry injections at the current drilling position, wherein the pressure of a grouting pump used by the first slurry injection in the multiple slurry injections is larger than or equal to that of the grouting pump in the other group of data, the pressure of the grouting pump used by the multiple slurry injections is gradually reduced, and the injection time is gradually prolonged.
According to the near-distance coal seam group goaf plugging drilling method provided by the invention, after the grouting pump capable of adjusting grouting pressure is used for controlling the slurry to be sprayed through the spraying nozzle in the process of drilling the drill hole by using the drill bit, the method further comprises the following steps:
monitoring the liquid level variation amplitude of bentonite slurry in the borehole;
Under the condition that the liquid level change amplitude is smaller than a preset threshold value, knowing that the viscous resistance of the injected slurry is equal to the pressure of bentonite slurry in the drilling hole, and controlling the drill bit to continuously drill the drilling hole by keeping the injected slurry at an original injection position;
and under the condition that the liquid level change amplitude is larger than or equal to the preset threshold value, performing secondary slurry injection on the drilling section in a preset range above the current drilling position of the drilling hole until the liquid level change amplitude is smaller than the preset threshold value.
According to the near-distance coal seam group goaf plugging drilling method provided by the invention, after the grouting pump capable of adjusting grouting pressure is used for controlling the slurry to be sprayed through the spraying nozzle in the process of drilling the drill hole by using the drill bit, the method further comprises the following steps:
and after the drilled hole passes through the current goaf, replenishing bentonite slurry into the drilled hole so as to protect the stability of the wall of the drilled hole.
According to the near-distance coal seam group goaf plugging drilling method provided by the invention, after the grouting pump capable of adjusting grouting pressure is used for controlling the slurry to be sprayed through the spraying nozzle in the process of drilling the drill hole by using the drill bit, the method further comprises the following steps:
And performing secondary slurry injection on the current goaf in the drill hole when the drill hole passes through the current goaf and enters a next goaf of the current goaf.
According to the near-distance coal seam group goaf plugging drilling method provided by the invention, the jet nozzle is detachably and fixedly connected to the drill bit.
According to the near-distance coal seam group goaf plugging drilling method provided by the invention, before the grouting pump after adjustment controls the slurry to be sprayed through the spraying nozzle, the method further comprises the following steps:
plugging the spray nozzle with a soft plug;
the cork is pressed out of the injection nozzle under the action of the grouting pump pressure.
According to the near-distance coal seam group goaf plugging drilling method provided by the invention, after the grouting pump capable of adjusting grouting pressure is used for controlling the slurry to be sprayed through the spraying nozzle in the process of drilling the drill hole by using the drill bit, the method further comprises the following steps:
after the borehole passes through the current goaf, extracting the jet nozzle and the drill bit from the borehole;
and after the spray nozzle is pre-plugged again, placing the drill bit into the drilling hole, and continuously drilling the drilling hole.
According to the near-distance coal seam group goaf plugging drilling method provided by the invention, the jet nozzle is arranged on the drill bit, the jet grouting is realized on the wall of the drill hole while drilling is performed, and the proper nozzle diameter, slurry concentration, slurry granularity, slurry consumption and grouting pump pressure are predetermined through a slurry jet test, so that the range of jet grouting is larger than the surrounding rock disturbance influence range of the wall of the drill hole, the loose surrounding rock around the wall of the drill hole is reinforced while drilling is performed, the construction period of geological drilling of the goaf is shortened, and the grouting cost during geological drilling is reduced by determining the surrounding rock disturbance influence range of the wall of the drill hole.
Drawings
In order to more clearly illustrate the invention or the technical solutions of the prior art, the following description will briefly explain the drawings used in the embodiments or the description of the prior art, and it is obvious that the drawings in the following description are some embodiments of the invention, and other drawings can be obtained according to the drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic flow chart of a method for plugging and drilling a goaf of a close-range coal seam group;
Fig. 2 is a schematic diagram of a structure of a drill bit and a jet nozzle mainly used for displaying in the method for plugging and drilling the goaf of the close-range coal seam group.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings, and it is apparent that the described embodiments are some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The following will be described first:
because the three belts have the characteristics, in the process of coal mine goaf investigation, mobile deformation monitoring and lower unstable space grouting treatment, the three belts are subjected to geological drilling by considering a single-layer mining space drilling process, even a drilling process of a close-range multilayer goaf, which is feasible in technology, economical and effective, so that technical support is provided for solving goaf investigation, overburden mobile deformation monitoring hole construction and lower unstable space grouting treatment problems occurring under different geological mining conditions.
At present, two common technical means are a grouting method goaf drilling technology and a casing drilling technology, and subsequent partial scholars are partially expanded and improved based on the two technologies.
The grouting method is used for penetrating the goaf drilling technology, the integrity reinforcement of the broken rock and soil body with a large area in the range of the collapse zone and the fracture zone can be realized, and after cement is solidified, drilling is continued in the slurry-rock solidified complete rock stratum, so that the drilling of the single-layer goaf and the long-distance multi-coal-seam goaf is realized. However, the drilling process for the room and pillar goaf with larger space and larger residual space or the goaf with thicker coal seam has poor applicability. Therefore, the drilling construction of the single-layer thick coal seam goaf or the multi-layer goaf which do not affect each other can be realized by providing high-concentration slurry to form a cone. However, the construction cost of the conventional grouting method through goaf drilling technology and the derived high-concentration slurry pillar type through goaf drilling technology for the near-distance coal seam goaf is greatly increased, and the construction period is greatly prolonged.
The casing drilling technology is suitable for drilling surface soil layers and broken rock bodies, but is not suitable for stratum conditions in which a large connectivity coal mining space exists to cause slurry leakage, otherwise, the construction of drilling cannot be safely performed under the condition that circulating slurry in holes does not exist. The casing-fixed pipe drilling technology needs to drill holes to a certain depth, then the casing is installed, cement slurry is adopted outside the wall for anchoring, and after the slurry is solidified, continuous drilling of broken rock mass can be realized, and the slurry leakage phenomenon on the casing can be avoided. However, the technology needs corresponding sleeve pipe series for protecting the hole wall of the multilayer goaf, and meanwhile, for a layer of goaf mined by a thick coal seam, particularly an ultra-thick coal seam, a multi-stage sleeve pipe protecting party is also needed to pass through the thicker coal seam goaf, so that the technology is complex and the construction period is long. Even this process often results in the inefficiency of the goaf drill hole because the casing progression is not sufficiently designed (typically the casing progression is equal to the number of goafs plus one).
Thus, there remains a need for a goaf geological drilling method that is less costly and has a shorter working time.
The method for plugging and drilling the goaf of the close-range coal seam group according to the invention is described below with reference to fig. 1-2, and comprises the following steps:
step 101, determining the surrounding rock disturbance influence range of the hole wall of a drilled hole based on a loose circle theory;
before the plugging drilling of the goaf of the coal seam group, the design of the exploratory hole of the ground goaf and the programming of the drilling implementation are also required by combining the plan view of the mining engineering of each coal seam of the mine, the up-down comparison graph and the coal mining process of the working face of each coal seam.
The coal mining process comprises the processes of room and pillar mining, roadway mining, blasting mining, long-wall type fully-mechanized caving and the like. The implementation scheme mainly comprises the design of the plane position of a goaf investigation hole, the hole depth, the hole diameter, the protection wall, the drilling process of goaf crack bands and caving bands under different coal mining process conditions and the like.
The loose coil theory is that in the drilling process, the rock mass around the drilling hole is subjected to stress change, so that the stress state of surrounding rock is changed from three directions to approximately two directions, the stress of the surrounding rock is redistributed and the local stress is concentrated, the rock strength is greatly reduced, and a loose breaking zone appears in the surrounding rock.
After the drilling implementation is written, the disturbance influence area of surrounding rock of the wall of the borehole hole is calculated based on the loose circle theory.
Specifically, in combination with actual disturbance conditions under the condition of the spiral drilling process of geological drilling, it is determined that rocks (including rock masses) outside a certain range from the center of the drilling hole are not affected by the disturbance of the geological drilling, and the area within the range is the disturbance influence area of surrounding rocks of the wall of the drilling hole.
The rock stratum in the disturbance influence range of the surrounding rock of the wall of the drilled hole is reinforced in a grouting mode, so that the rock stratum is condensed into a whole, and phenomena of drill falling, drill sticking and the like caused by loosening of the wall of the drilled hole during geological drilling can be effectively avoided.
It should be noted that the range of grouting to the formation pore and fracture should be larger than the disturbance influence area of the borehole wall surrounding rock calculated theoretically.
Optionally, the radius of the disturbance influence area of the surrounding rock of the wall of the drilling hole is expressed in a mode of multiple of the radius of the drilling hole, and when the ratio of the radius of the disturbance influence area of the surrounding rock of the wall of the drilling hole to the radius of the drilling hole is not an integer, the method is used for rounding upwards so as to ensure that the range of grouting treatment of the rock stratum is larger than the disturbance influence area of the surrounding rock of the wall of the drilling hole.
For example, under a certain geological mining condition of a coal mine, according to theoretical calculation results, the acting force of surrounding rock of the wall of a borehole hole on rock on the surface of the wall of the hole gradually weakens along with the increasing distance from the center of the borehole, and gradually tends to original rock stress; in geological drilling, it is often considered that a distance of 4 times of the drilling radius is not disturbed by drilling construction, i.e. a rock mass outside the distance has no acting force on the hole wall.
Wherein a range of radii R equal to five times the borehole radius a is determined.
102, determining the diameter of an injection nozzle, the concentration of slurry, the granularity of the slurry, the pressure of a grouting pump and the consumption of the slurry corresponding to the slurry injection in the drilling hole through a slurry injection test, so that the injection range of the slurry reaches the surrounding rock disturbance influence range of the wall of the drilling hole, and the pumping pressure of the grouting pump is larger than a preset threshold value;
high pressure slurry injection tests were performed in a surface laboratory.
Alternatively, in the slurry injection test, the injection nozzles with different diameters, slurries with different concentrations, slurries with different particle sizes and grouting pumps with different pressures are used, and the injection ranges and the slurry consumption under the conditions of different injection nozzle diameters, different slurry concentrations, different slurry particle sizes and different grouting pump pressures are tested in a control variable manner.
And recording and determining the corresponding jet nozzle diameter, slurry concentration, slurry granularity, grouting pump pressure and slurry consumption when the jet range of the slurry reaches the surrounding rock disturbance influence range of the wall of the drilled hole.
The grouting pump pressure needs to be larger than a preset threshold, and the preset threshold is determined empirically to achieve the effect of high-pressure injection.
Step 103, configuring the slurry according to the slurry concentration, the slurry granularity and the slurry consumption, manufacturing a jet nozzle with the diameter of the jet nozzle, installing the jet nozzle on a drill bit, and adjusting the pressure of a grouting pump according to the pressure of the grouting pump;
And according to the determined slurry concentration, slurry granularity and slurry consumption, configuring slurry with corresponding concentration and volume by adopting materials with corresponding granularity.
The spray nozzle is arranged on the drill bit of the drilling tool according to the determined diameter of the spray nozzle, and the arrangement mode of the spray nozzle is not limited in the embodiment.
And correspondingly adjusting the grouting pump according to the determined grouting pump pressure.
Step 104, controlling the slurry to be sprayed through the spraying nozzle by the grouting pump with adjustable grouting pressure during the process of drilling the drill hole by using the drill bit.
In the process of drilling a borehole by using a drill bit provided with a jet nozzle, the pump pressure of the grouting pump is adjusted to be a determined pressure, the wall of the borehole is subjected to jet grouting by using slurry which is correspondingly configured through the jet nozzle, and the range of the jet grouting is larger than the surrounding rock disturbance influence range of the wall of the borehole.
According to the invention, the injection nozzle is arranged at the upper part of the drill bit, injection grouting is realized on the wall of the drill hole while drilling the drill hole, and proper nozzle diameter, slurry concentration, slurry granularity, slurry consumption and grouting pump pressure are predetermined through a slurry injection test, so that the range of injection grouting is larger than the surrounding rock disturbance influence range of the wall of the drill hole, reinforcement of loose surrounding rock around the wall of the drill hole is realized while drilling the drill hole, the construction period of geological drilling of a goaf is shortened, and the grouting cost during geological drilling is reduced by determining the surrounding rock disturbance influence range of the wall of the proper drill hole.
In the plugging drilling method for the goaf of the close-range coal seam group, the determination of the diameter of the injection nozzle, the concentration of the slurry, the granularity of the slurry, the pressure of the grouting pump and the consumption of the slurry corresponding to the slurry injection in the drilling hole through the slurry injection test comprises the following steps:
and (3) performing a slurry injection test under the geological environment where the drilling hole is located, and determining the injection pump pressure and the slurry consumption required by the injection range of the slurry reaching the surrounding rock disturbance influence range of the wall of the drilling hole under the conditions of different injection nozzle diameters, different slurry concentrations and different slurry granularity.
The geological environment includes formation conditions of the geological borehole, coal mining process to be passed through the coal seam group, time to be passed through the coal seam, slurry concentration in the geological borehole, and fluid level position in the borehole, etc.
Specifically, different geological mining conditions, different pore development levels of the rock formation. For example, the extent of pore development of the collapsed band is greater than the extent of pore development of the fractured band; the pore development degree of the hard rock layer is larger than that of the weak rock layer.
The coal mining process to be passed through the coal seam group is different, and the pore development degree of the rock stratum is also different.
The longer the time to mine through the coal seam, the higher the compaction of the formation and the lower the pore development.
The rapid drop in the fluid level in the borehole reflects the sudden loss of slurry in the borehole, here pore development or void space, caused by the sudden exposure of a larger pore fracture development zone during drilling.
Because the pore development degree of the rock stratum at the periphery of the drilling hole is different at different positions of geological environment, the required diameter of the injection nozzle, the concentration of the slurry, the granularity of the slurry, the pressure of the grouting pump and the consumption of the slurry are also different under the condition that the injection range of the slurry reaches the disturbance influence range of the surrounding rock at the wall of the drilling hole.
Therefore, in the slurry injection test, different geological environments are simulated, and the grouting pump pressure and the slurry consumption required by the surrounding rock disturbance influence range of the wall of the drilled hole under different geological environments, different injection nozzle diameters, different slurry concentrations and different slurry granularity are determined.
Specifically, during slurry injection test, the effective nozzle diameter, slurry pump pressure, slurry consumption and other values are recorded under different cement slurry concentration and particle size conditions in a mode of controlling variables to carry out orthogonal test, and corresponding slurry pump pressure and slurry consumption volume under different nozzle diameters, different cement slurry concentrations and different particle size conditions are determined.
Wherein the different nozzle diameters recorded include 1.6, 1.8, 2.0, 2.2, 2.4, 2.6, 2.8, 3.0, 3.2, 3.4 in millimeters.
The noted cement to cement ratios include 0.5:1, 0.8:1, 1:1, 1.2:1, 1.4:1, 1.5:1.
The different particle size conditions recorded are the type and class of cement.
According to the invention, different geological environments revealed by drilling are simulated during a slurry injection test, and further, under the condition that the slurry injection range reaches the disturbance influence range of surrounding rock on the wall of a drilled hole, the proper grouting pump pressure and slurry consumption are determined by reasonably selecting the diameter of the injection nozzle, the slurry concentration and the slurry granularity, so that the slurry consumption during grouting to reinforce the surrounding rock on the periphery of the drilled hole is effectively controlled, the grouting treatment cost is further reduced, and the geological drilling cost is further reduced.
In the plugging and drilling method for the goaf of the close-range coal seam group, the slurry is prepared according to the concentration of the slurry, the granularity of the slurry and the consumption of the slurry, a jet nozzle with the diameter of the jet nozzle is manufactured and arranged on a drill bit, and a grouting pump is adjusted according to the pressure of the grouting pump, and the method comprises the following steps:
selecting a set of effective data from a plurality of sets of data obtained by the slurry injection test under the condition that the current drilling position of the drilling hole is a fracture zone of a current goaf, wherein each set of data comprises an injection nozzle diameter, a slurry concentration, a slurry granularity, a slurry injection pump pressure and a slurry consumption;
As the borehole drills into the fracture zone, injection grouting is required to drill Zhou Cekong gap-developing surrounding rock in the zone of the fracture zone.
A set of valid data is selected from a plurality of sets of data obtained from a slurry injection test, each set of data including injection nozzle diameter, slurry concentration, slurry particle size, grouting pump pressure, and slurry consumption. The selected set of data is needed to satisfy the effective data of the slurry injection range reaching the surrounding rock disturbance influence range of the hole wall of the borehole in the fracture zone range.
Wherein, when selecting the data, the proper slurry concentration, slurry granularity and spray nozzle diameter are determined under the condition that the spray distance is the optimal spray distance. It should be noted that the slurry particle size is less than 1/4 of the nozzle outlet diameter.
Configuring the slurry according to the selected set of data, installing a jet nozzle on the drill bit, and adjusting a grouting pump pressure of the grouting pump;
and determining the diameter of a spray nozzle, the pressure of a grouting pump and the materials and the concentration of slurry configuration when spraying grouting according to the selected data, and configuring the slurry with the volume corresponding to the consumption of the slurry.
According to the selected diameter of the jet nozzles, the jet nozzles with the corresponding diameters are manufactured and processed, and the jet nozzles with the selected diameters are arranged on the upper part of the drill bit.
In a possible embodiment, the installation position of the jet nozzle is shown in fig. 2, the jet nozzle is installed on the upper part of the drill bit during the goaf drilling process in a certain stratum, the diameter of the jet nozzle is 2.2 mm, and the diameter of the jet nozzle in other goafs in similar stratum can be 1.8 mm, 2.2 mm, 2.6 mm or 3.0 mm.
The drill bit is a specially-customized lengthened alloy drill bit, the spraying nozzles are arranged on the upper part of the alloy drill bit at intervals along the axial direction of the alloy drill bit, 3 spraying nozzles are arranged at intervals around the circumference of the alloy drill bit in each row, and meanwhile, the two rows of spraying nozzles are distributed in a quincuncial staggered mode, so that slurry can be sprayed out of the spraying nozzles on a drilled hole more uniformly.
After the setting of the slurry and the jet nozzle is completed, cement mortar is screened, the pressure and flow of slurry pump are regulated, and the prevention plugs in the jet nozzle are removed, so that the free jet of the jet nozzle is realized, and the solidification effect of loosely disturbing rock formations (blocks) at a deep distance is realized when a fracture zone drills.
Selecting another set of data from the sets of data obtained by the slurry injection test under the condition that the current drilling position of the drilling hole is the caving zone of the current goaf;
when the borehole drills to the collapse zone, injection grouting is required for the borehole Zhou Cewei rock in the range of the collapse zone. Because the pore development degree of the collapse zone and the fracture zone is different, the data required to be selected are different under the influence range of surrounding rock disturbance of the wall of the same drilling hole.
And selecting another set of data from the plurality of sets of data obtained by the slurry injection test, wherein each set of data comprises the diameter of an injection nozzle, the concentration of slurry, the granularity of the slurry, the pressure of a grouting pump and the consumption of the slurry, so that when drilling to a collapse zone, the range of slurry injection can still reach the disturbance influence range of surrounding rock of the wall of a drilled hole.
Another set of data is also selected to be effective data to meet the range of slurry injection reaching the range of borehole wall surrounding rock disturbances in the zone of collapse.
Configuring the slurry according to the selected other set of data, installing a jet nozzle on the drill bit, and adjusting the grouting pump pressure of the grouting pump;
and determining the diameter of a spray nozzle, the pressure of a grouting pump and the materials and the concentration of slurry configuration when spraying grouting according to the selected data, and configuring the slurry with the volume corresponding to the consumption of the slurry.
According to the selected diameter of the jet nozzle, manufacturing and processing the jet nozzle with the corresponding diameter, and installing the jet nozzle with the selected diameter on the upper part of the drill bit.
Optionally, when the diameters of the jet nozzles are the same in the two selected groups of data, the jet nozzles can be fixedly communicated with the drill bit in a welding mode or the like; when the diameters of the spray nozzles are different in the two selected groups of data, drill bits welded with the spray nozzles with different diameters can be selected, the spray nozzles can be detachably fixedly connected to the drill bits, and after a crack zone is drilled to a collapse zone, the spray nozzles with the diameters corresponding to the collapse zone are replaced.
Wherein the pump pressure of the slurry in the set of data is greater than the pump pressure of the slurry in the other set of data, the slurry concentration in the set of data is less than the slurry concentration in the other set of data, and the slurry particle size in the set of data is less than the slurry particle size in the other set of data.
Specifically, since the pore development degree of the fracture zone is smaller than that of the collapse zone, in order to enable the slurry injected when drilling into the collapse zone to reach the wall surrounding rock disturbance influence range of the drilled hole, the slurry concentration in the other set of data corresponding to the collapse zone is greater than that in the set of data corresponding to the fracture zone.
The slurry particle size in the other set of data corresponding to the fractured zone is greater than the slurry particle size in the set of data corresponding to the fractured zone.
The grouting pump pressure in the other set of data corresponding to the fractured zone is less than the grouting pump pressure in the set of data corresponding to the fractured zone.
And (3) respectively selecting a plurality of groups of data for grouting the collapse zone and the fracture zone, wherein the pump pressure of each stage of grouting pump used for grouting the collapse zone is smaller than that used for grouting the fracture zone. The collapse zone and the fracture zone generally adopt decreasing three-stage grouting pressure.
After the setting of the slurry and the jet nozzle is finished, the cement mortar is still screened, the pressure and the flow of the slurry pump are regulated, and the blockage prevention in the jet nozzle is removed, so that the free jet of the jet nozzle is realized, and the solidification effect of the deep-distance loose disturbance rock stratum (block) is realized when the collapse zone is drilled.
The invention relates to a plugging drilling method for goafs of a close-range coal seam group, which is characterized in that a grouting pump is adjusted according to the pressure of the grouting pump and comprises the following steps:
under the condition that the current drilling position of the drill hole is a fracture zone of a current goaf, performing multiple slurry injections at the current drilling position, wherein the pressure of a grouting pump used for the first slurry injection in the multiple slurry injections is larger than or equal to that of the grouting pump in the group of data, the pressure of the grouting pump used for the multiple slurry injections is gradually reduced, and the injection time is gradually prolonged;
in the case where the current drilling position of the borehole is the fracture zone of the current goaf, a multi-stage pressure-split injection process.
Wherein the grouting pump pressure is generally not less than 20MPa. When stratum environments are different, the grouting pump pressure can be flexibly adjusted.
Specifically, when drilling and jetting the fracture zone, multiple slurry jetting is performed at the current drilling position, the pump pressure of the grouting pump used for the first slurry jetting in the slurry jetting is greater than or equal to the pump pressure of the grouting pump in the selected group of data, the pump pressure of the grouting pump used for the multiple slurry jetting is gradually reduced, and the jetting time is gradually prolonged.
For example, under a certain stratum condition, cement mortar with the water-solid ratio of 0.6:1-1:1 is selected, and meanwhile, in order to facilitate the drilling operation in a fracture zone while spraying, a proper amount of water glass is added into the slurry, so that the solidification time of the slurry is reduced.
In the first slurry spraying process, the pressure of the slurry at the outlet of the first-stage spraying nozzle is 9MPa, and the spraying time of the crack zone is not less than 15s.
And in the second slurry spraying process, the pressure of the slurry at the outlet of the second-stage spraying nozzle is 6MPa, and the spraying time of the fracture zone is not less than 20s.
In the third slurry spraying process, the pressure of the slurry at the outlet of the third-stage spraying nozzle is 3MPa, and the spraying time of the crack zone is not less than 30s.
And under the condition that the current drilling position of the drill hole is the collapse zone of the current goaf, performing multiple slurry injections at the current drilling position, wherein the pressure of a grouting pump used by the first slurry injection in the multiple slurry injections is larger than or equal to that of the grouting pump in the other group of data, the pressure of the grouting pump used by the multiple slurry injections is gradually reduced, and the injection time is gradually prolonged.
Under the condition that the current drilling position of the drilling hole is the collapse zone of the current goaf, a multi-stage pressure-fractional injection process is also adopted, and the implementation mode is the same as that when the drilling position is in a fracture zone, and only the values of the grouting pump pressure and the injection time are changed, so that the repeated description is omitted.
In one possible implementation, cement mortar with a water-solid ratio of 1:1-1:1.5 is selected under certain stratum conditions, and a proper amount of water glass is added into the slurry to reduce the solidification time of the slurry.
When the slurry is sprayed for the first time, the pressure of the slurry liquid at the outlet of the first-stage spraying nozzle is 4MPa, and the spraying time in a collapse zone is not less than 20s.
And in the second slurry spraying process, the pressure of the cement slurry at the outlet of the second-stage spraying nozzle is 3MPa, and the spraying time in the collapse zone is not less than 30s.
And in the third slurry injection, the pressure of the slurry at the outlet of the third-stage injection nozzle is 2MPa, and the injection time in the collapse zone is not less than 40s.
The invention realizes the multi-stage pressure split injection of the pore cracks in the fracture zone and the collapse zone by using the multi-stage-split grouting injection process in the fracture zone and the collapse zone and adjusting the speed of high-pressure injection slurry by adjusting the pressure of the grouting pump, and further realizes continuous operation while drilling operation and waiting for slurry and rock solidification to form a whole under the pressure effect of the slurry in the hole, thereby preventing the slurry in the hole from being lost.
Simultaneously, grouting parameters such as grouting pressure, grouting time and slurry concentration are adjusted at drilling positions with different pore crack development conditions, and the grouting parameters are adjusted to control slurry to achieve the effect that the injection distance of the slurry is larger than the surrounding rock disturbance influence range of the wall of a drilled hole under different geological environments, so that the purpose of crushing rock around the drilled hole is achieved.
In the near-distance coal seam group goaf plugging drilling method, after the grouting pump capable of adjusting grouting pressure is used for controlling the slurry to be sprayed through the spraying nozzle in the process of drilling the drill hole by using the drill bit, the method further comprises the following steps:
monitoring the liquid level variation amplitude of bentonite slurry in the borehole;
when drilling a borehole, bentonite slurry is injected into the borehole to protect the wall of the borehole, and the three-dimensional stress state of the borehole is maintained, so that the slurry viscous resistance sprayed in the pore gap of the borehole wall, the pressure of the bentonite slurry in the borehole and the water pressure of the pore gap in the rock mass are equal; or when no water level exists in the rock stratum, the slurry viscosity resistance sprayed in the pore cracks is equal to the slurry pressure of bentonite in the pores.
On the basis, the slurry sprayed at high pressure is solidified to form slurry-broken rock mass cementing body, and the stability of the rock mass in the disturbance influence range of the surrounding rock of the hole wall and the hole wall of the drilled hole is supported together.
The change of the height of the bentonite slurry liquid level in the drilling hole reflects the pore development condition of the rock stratum around the drilling hole, and the rapid drop of the liquid level position in the drilling hole reflects the sudden leakage of slurry in the hole caused by the sudden disclosure of a larger pore crack development area in the drilling process.
That is, drilling into the relatively developed or empty pores of the void.
Thus, during the drilling of the borehole, changes in the level of the slurry within the borehole are observed and recorded to determine pore development of the formation surrounding the borehole.
In this embodiment, the observation mode of the liquid level is not limited.
Under the condition that the liquid level change amplitude is smaller than a preset threshold value, knowing that the viscous resistance of the injected slurry is equal to the pressure of bentonite slurry in the drilling hole, and controlling the drill bit to continuously drill the drilling hole by keeping the injected slurry at an original injection position;
the preset threshold is determined empirically.
When the liquid level change amplitude is smaller than a preset threshold value, the method indicates that the holes of the rock stratum around the drilling hole are fewer, the treatment effect of the cracks in the drilling hole is better, and drilling can be continued.
Meanwhile, when the water level in the rock stratum is not available, the viscosity resistance of the injected slurry is equal to the pressure of bentonite slurry in the drill hole, the inside of the hole is in a stress balance state, the injected slurry can be kept in the original position, and the drilling can be continued. If the viscous resistance of the injected slurry is not equal to the pressure of the bentonite slurry in the drill hole, the injected slurry cannot be kept in the original position, and the fact that the cracks around the drill hole are not completely filled is indicated, the injection of the injected slurry into the hole is needed to be continued until the injected slurry can be kept in the original position.
Optionally, when there is a water level in the formation, it is necessary to observe and determine that the viscous drag of the injected slurry, the pressure of the bentonite slurry in the borehole, and the water pressure in the bore of the rock mass are all equal, at which time the injected slurry can remain in place and continue to drill down.
Alternatively, drilling may continue with deep cement slurry solids disturbance resistant when the current drilling position of the borehole is in the zone of collapse.
And under the condition that the liquid level change amplitude is larger than or equal to the preset threshold value, performing secondary slurry injection on the drilling section in a preset range above the current drilling position of the drilling hole until the liquid level change amplitude is smaller than the preset threshold value.
When the liquid level change amplitude is larger than a preset threshold value, the rock stratum around the drilling hole suddenly enters a region with larger pores, and the risk of hole wall collapse, drill falling or drill sticking is continuously caused, so that the drilling section in the preset range above the current position needs to use cement mortar again to perform slurry injection, and the rock stratum around the drilling hole above the current position is secondarily reinforced until the liquid level change amplitude is smaller than the preset threshold value.
Wherein the preset range is empirically determined.
In one possible embodiment, the predetermined range may be a fracture zone of a new drilling section within the borehole.
According to the invention, the pore development condition of rock formations around the drilling hole is determined by observing the liquid level variation amplitude in the drilling hole, and drilling is continued when the liquid level variation amplitude is smaller than the preset threshold value, so that the construction period of geological drilling is shortened; and when the change amplitude of the liquid level is larger than a preset threshold value, performing slurry injection again on the drilling section in a preset range above the drilling section to realize secondary reinforcement so as to prevent the stratum with larger porosity from influencing geological drilling.
In the near-distance coal seam group goaf plugging drilling method, after the grouting pump capable of adjusting grouting pressure is used for controlling the slurry to be sprayed through the spraying nozzle in the process of drilling the drill hole by using the drill bit, the method further comprises the following steps:
and after the drilled hole passes through the current goaf, replenishing bentonite slurry into the drilled hole so as to protect the stability of the wall of the drilled hole.
After the drilling passes through the current goaf, the bentonite slurry is supplemented into the drilling hole through the drill rod at low pressure, the bentonite slurry lost from the crack of the hole wall before the injection of the slurry is supplemented into the drilling hole, the protection is continuously formed on the hole wall, the three-dimensional stress state in the hole is maintained, namely the stability of the hole wall is maintained, and a foundation is laid for the follow-up continuous drilling.
The upper part of the current goaf is a crack zone with smaller pore cracks, and the lower part is a caving zone with larger pores and other coal seam goafs.
In the near-distance coal seam group goaf plugging drilling method, after the grouting pump capable of adjusting grouting pressure is used for controlling the slurry to be sprayed through the spraying nozzle in the process of drilling the drill hole by using the drill bit, the method further comprises the following steps:
and performing secondary slurry injection on the current goaf in the drill hole when the drill hole passes through the current goaf and enters a next goaf of the current goaf.
When a drilled hole enters the next goaf of the current goaf through the current goaf, or in the geological drilling process of the goaf of the coal seam at too short distance, secondary mining of the wall of the drilled hole at the upper part is easily caused by continuous drilling downwards, so that cracks are generated again on the wall of the drilled hole at the upper part, and in the drilled hole, the crack zone and the caving zone of the coal seam at the upper part of the current goaf are required to be sprayed with grouting materials at high pressure again by using the same multi-stage pressure-split spraying technology, so that the wall of the drilled hole of the current goaf is secondarily reinforced.
After the drilling hole enters the next goaf of the current goaf, the same multi-stage pressure-multi-stage injection technology is still adopted, when the drilling hole is drilled to a crack zone and a collapse zone of the next goaf, high-pressure slurry is injected to the periphery of the drilling hole while drilling, so that the slurry is filled into a rock mass in the influence range of surrounding rock disturbance of the wall of the drilling hole, and a cementing body is formed with the rock mass after solidification, so that the stability of the wall of the drilling hole is enhanced.
Optionally, when the current goaf enters the next goaf and the disturbance influence of the upper goaf is small, the crack zone and the caving zone in the next goaf can be drilled and injected with grouting first, then the last goaf is injected with grouting for a second time for reinforcement, and geological drilling engineering of the close-range coal seam goaf is completed from bottom to top.
According to the invention, the goaf and the goaf of the close-range coal seam group are drilled while injecting grouting, and simultaneously, a multi-stage and multi-stage grouting process is adopted, so that drilling operation is performed while under the self pressure of the slurry in the hole, and the slurry is drilled while waiting for solidification of rock mass in the disturbance influence range of the slurry and the wall surrounding rock of the drilled hole to form a cementing body, thereby achieving continuous operation of drilling engineering, controlling the time of geological drilling engineering of the goaf, and having stronger feasibility and better operability.
In the near-distance coal seam group goaf plugging drilling method, the jet nozzle is detachably and fixedly connected to the drill bit.
The upper part of the alloy drill bit is internally provided with a hole at a certain distance, the hole wall is provided with internal threads, the injection nozzle is provided with external threads matched with the internal threads, and the injection nozzle is fixed on the drill bit in a threaded connection mode to realize the detachable typeFixedly connected withWhen the diameters of the injection nozzles are required to be different, the same drill is convenient to useThe upper head region is replaced with spray nozzles of different diameters.
The plugging drilling method for the goaf of the close-range coal seam group, disclosed by the invention, comprises the following steps before the slurry is controlled to be sprayed through the spraying nozzle by the regulated grouting pump:
plugging the spray nozzle with a soft plug;
because the jet nozzle is in compound communication with the upper part of the drill bit, the circulating slurry in the drill rod and the cement slurry to be sprayed at high pressure can block the jet nozzle during the drilling; meanwhile, the injection nozzle is prevented from being blocked by the wall mudstone of the drilled hole, the binding body of sandy mudstone and the particles of the sandy rock during the running, so that the injection nozzle is blocked by a soft plug before the running.
With continued reference to fig. 2, the cork may alternatively be a compressed wood, red wine cork or 703 cork. Wherein, 703 soft glue is an organic siliceous material with soft quality and high strength.
In one possible embodiment, under certain stratum conditions, the diameter of the jet nozzle is 2.2 mm, and because the diameter of the jet nozzle is smaller, the inner wall of the jet nozzle is smeared with lubricating oil before the soft plug is put in, and then the soft plug 703 is put in the jet nozzle to seal the jet nozzle.
Because the nozzle coated with the lubricating oil is smoother, and the 703 soft rubber also has certain strength, the spray nozzle keeps a sealing state under the action of circulating slurry with normal pressure.
The cork is pressed out of the injection nozzle under the action of the grouting pump pressure.
Under the action of the grouting pump, the pressure of the slurry in the drill bit is increased, and the 703 soft rubber plug is extruded out of the injection nozzle and is destroyed under the action of high pressure, so that the injection nozzle is kept in an open state, and then the cement slurry is injected through the injection nozzle under high pressure.
According to the invention, the soft plug is embedded in the injection nozzle, so that the drill bit can not be blocked by circulating slurry in the drill rod or cement slurry with high-pressure injection during normal drill down, and the injection nozzle is prevented from being blocked by mudstone during drill down; when the drill bit drills to the areas needing to be injected with the injection slurry, such as a fracture zone, a collapse zone and the like, the soft plug can be flushed away by the pressure of the injection slurry, and the normal operation of the injection slurry is ensured.
In the near-distance coal seam group goaf plugging drilling method, after the grouting pump capable of adjusting grouting pressure is used for controlling the slurry to be sprayed through the spraying nozzle in the process of drilling the drill hole by using the drill bit, the method further comprises the following steps:
after the borehole passes through the current goaf, extracting the jet nozzle and the drill bit from the borehole;
after the drilling passes through the current goaf, the drill bit and the injection nozzle arranged on the drill bit are lifted, and the injection nozzle on the drill bit is flushed by water flow under high pressure, so that the injection nozzle is kept in an open state, and the subsequent injection grouting is realized.
And after the spray nozzle is pre-plugged again, placing the drill bit into the drilling hole, and continuously drilling the drilling hole.
And selecting a soft plug to block the injection nozzle, then placing the drill bit into a drilled hole, continuously drilling, and flushing the soft plug with slurry by high pressure when the drill bit is drilled to the next position where the injection slurry needs to be injected.
According to the invention, the drill bit is lifted and the soft plug is replaced after the drill bit passes through one layer of goaf, so that the normal slurry circulation in the drill bit is maintained when the drill bit continues to drill to the next layer of goaf; the soft plug plugging drill bit has lower cost and convenient operation and higher practicability.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and are not limiting; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims (10)
1. The method for plugging and drilling the goaf of the close-range coal seam group is characterized by comprising the following steps of:
determining the surrounding rock disturbance influence range of the hole wall of the drill hole based on a loosening ring theory;
determining the diameter of an injection nozzle, the concentration of the slurry, the granularity of the slurry, the pressure of a grouting pump and the consumption of the slurry corresponding to the slurry injection in the drilling hole through a slurry injection test, so that the injection range of the slurry reaches the surrounding rock disturbance influence range of the wall of the drilling hole, and the pressure of the grouting pump is larger than a preset threshold;
preparing the slurry according to the slurry concentration, the slurry granularity and the slurry consumption, manufacturing a jet nozzle with the diameter of the jet nozzle, installing the jet nozzle on a drill bit, and adjusting a grouting pump according to the pressure of the grouting pump;
The slurry is controlled to be injected through the injection nozzle by the grouting pump with adjustable grouting pressure during the drilling of the borehole by using the drill bit.
2. The near seam group goaf plugging drilling method of claim 1, wherein determining, by the slurry injection test, a nozzle diameter, a slurry concentration, a slurry particle size, a grouting pump pressure, and a slurry consumption corresponding to the slurry injection in the borehole comprises:
and (3) performing a slurry injection test under the geological environment where the drilling hole is located, and determining the injection pump pressure and the slurry consumption required by the injection range of the slurry reaching the surrounding rock disturbance influence range of the wall of the drilling hole under the conditions of different injection nozzle diameters, different slurry concentrations and different slurry granularity.
3. The near seam group goaf plugging drilling method of claim 2, wherein said configuring said slurry according to said slurry concentration, slurry particle size and slurry consumption, making a jet nozzle having said jet nozzle diameter, installing said jet nozzle on a drill bit, and adjusting a grouting pump according to said grouting pump pressure, comprises:
selecting a set of data from a plurality of sets of data obtained by the slurry injection test, each set of data including injection nozzle diameter, slurry concentration, slurry particle size, grouting pump pressure and slurry consumption, in the case that the current drilling position of the borehole is a fracture zone of the current goaf;
Configuring the slurry according to the selected set of data, installing a jet nozzle on the drill bit, and adjusting a grouting pump pressure of the grouting pump;
selecting another set of data from the sets of data obtained by the slurry injection test under the condition that the current drilling position of the drilling hole is the caving zone of the current goaf;
configuring the slurry according to the selected other set of data, installing a jet nozzle on the drill bit, and adjusting the grouting pump pressure of the grouting pump;
wherein the pump pressure of the slurry in the set of data is greater than the pump pressure of the slurry in the other set of data, the slurry concentration in the set of data is less than the slurry concentration in the other set of data, and the slurry particle size in the set of data is less than the slurry particle size in the other set of data.
4. A near seam group goaf plugging drilling method as claimed in claim 3, wherein said adjusting the grouting pump according to the grouting pump pressure comprises:
under the condition that the current drilling position of the drill hole is a fracture zone of a current goaf, performing multiple slurry injections at the current drilling position, wherein the pressure of a grouting pump used for the first slurry injection in the multiple slurry injections is larger than or equal to that of the grouting pump in the group of data, the pressure of the grouting pump used for the multiple slurry injections is gradually reduced, and the injection time is gradually prolonged;
And under the condition that the current drilling position of the drill hole is the collapse zone of the current goaf, performing multiple slurry injections at the current drilling position, wherein the pressure of a grouting pump used by the first slurry injection in the multiple slurry injections is larger than or equal to that of the grouting pump in the other group of data, the pressure of the grouting pump used by the multiple slurry injections is gradually reduced, and the injection time is gradually prolonged.
5. A method of lost circulation drilling in a goaf of a close-up coal seam group as claimed in any one of claims 1 to 4, wherein said controlling said injection of said slurry through said injection nozzle by said injection pump with adjustable injection pressure during drilling of said borehole with said drill bit further comprises:
monitoring the liquid level variation amplitude of bentonite slurry in the borehole;
under the condition that the liquid level change amplitude is smaller than a preset threshold value, knowing that the viscous resistance of the injected slurry is equal to the pressure of bentonite slurry in the drilling hole, and controlling the drill bit to continuously drill the drilling hole by keeping the injected slurry at an original injection position;
and under the condition that the liquid level change amplitude is larger than or equal to the preset threshold value, performing secondary slurry injection on the drilling section in a preset range above the current drilling position of the drilling hole until the liquid level change amplitude is smaller than the preset threshold value.
6. A method of lost circulation drilling in a goaf of a close-up coal seam group as claimed in any one of claims 1 to 4, wherein said controlling said injection of said slurry through said injection nozzle by said injection pump with adjustable injection pressure during drilling of said borehole with said drill bit further comprises:
and after the drilled hole passes through the current goaf, replenishing bentonite slurry into the drilled hole so as to protect the stability of the wall of the drilled hole.
7. A method of lost circulation drilling in a goaf of a close-up coal seam group as claimed in any one of claims 1 to 4, wherein said controlling said injection of said slurry through said injection nozzle by said injection pump with adjustable injection pressure during drilling of said borehole with said drill bit further comprises:
and when the drilled hole passes through the current goaf and enters the next goaf of the current goaf, performing slurry injection again in the same process on the current goaf in the drilled hole.
8. A near seam group goaf plugging drilling method as claimed in any one of claims 1 to 4 wherein the jet nozzle is removably and fixedly connected to the upper portion of the drill bit.
9. A method of lost circulation drilling in a goaf of a close-up coal seam group according to any one of claims 1 to 4, further comprising, prior to said controlling of said slurry by said regulated grouting pump by said jet nozzle:
plugging the spray nozzle with a soft plug;
the cork is pressed out of the injection nozzle under the action of the grouting pump pressure.
10. The near seam group goaf plugging drilling method of claim 9, wherein the controlling the slurry by the injection pump with adjustable injection pressure after injecting the slurry through the injection nozzle during the drilling of the borehole by the drill bit further comprises:
after the borehole passes through the current goaf, extracting the jet nozzle and the drill bit from the borehole;
and after the spray nozzle is pre-plugged again, placing the drill bit into the drilling hole, and continuously drilling the drilling hole.
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