CN103075181B - Bedding long drilling hole seam cutting and hole washing integral coal bed gas extraction method - Google Patents
Bedding long drilling hole seam cutting and hole washing integral coal bed gas extraction method Download PDFInfo
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- CN103075181B CN103075181B CN201310041318.XA CN201310041318A CN103075181B CN 103075181 B CN103075181 B CN 103075181B CN 201310041318 A CN201310041318 A CN 201310041318A CN 103075181 B CN103075181 B CN 103075181B
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Abstract
The invention provides a bedding long drilling hole seam cutting and hole washing integral coal bed gas extraction method, which belongs to the technical field of improved coal rock body permeable coal bed gas extraction method and aims at solving the technical problem to provide the bedding long drilling hole seam cutting and hole washing integral coal bed gas extraction method with the advantages that the bedding long drilling hole well wall stress is scattered, the influence range is wide, and the extraction efficiency is high. The method adopts the technical scheme that a, a bedding long drilling hole is drilled in a coal bed for coal bed gas extraction; b, drill withdrawal is carried out, high-pressure water is introduced, a drill rotates in situ, and a large vertical crack is formed on the plane vertical to the axial line of the bedding long drilling hole; c, the drill withdrawal is continuously carried out, the water pressure is reduced, the hole wall of the bedding long drilling hole is flushed, the drill is stopped after going back for a distance, and a new large vertical crack is constructed by a method in the step b; d, the step c is repeated so that a plurality of large vertical cracks are formed on the bedding long drilling hole; e, the drill is withdrawn, and the hole sealing is carried out on the bedding long drilling hole; and f, coal bed gas is extracted. The method provided by the invention has the advantages that the extraction efficiency is high, and the method is suitable for underground extraction.
Description
Technical field
Concordant long drilled holes slot hole flushing integration extraction coal bed gas method of the present invention, belongs to down-hole and improves coal and rock permeability extraction coal bed gas method and technology field.
Background technology
As long as cut coal; just have coal bed gas (gas) to gush out; coal bed gas (gas) is one of major casualty threatening Safety of Coal Mine Production and miner's life; simultaneously coal bed gas is again a kind of clean energy resource, develop coal bed gas to guarantee Safety of Coal Mine Production, protection of the environment, improve energy resource structure etc. all there is great economy and social benefit.China buried depth 2000m is with in shallow scope, and Coal bed gas project is about 31,000,000,000,000 side's reserves, and permeability is generally less than 1 × 10
-3μm
2, generally belong to hyposmosis coal seam reservoirs, coal bed gas is difficult to by extraction, is extraction coal bed gas effective in down-hole, have employed many engineering measures and carry out enhanced transformation to coal and rock.Such as: the technology such as the intensive boring exploitation of major diameter, Mining Protective Seam, layer-through drilling and boring both sides hydraulic slotted liner technique, but totally produce little effect, common boring can form extending stress band around, gas permeability of coal seam is reduced, hinders the infiltration of coal bed gas.Mining Protective Seam is inapplicable to single coal bed.Layer-through drilling coal seam drilling encountering rate is low, and need open up floor roadway." coal journal " 2001.vol26, No5 " research of a hyposmosis coal seam reservoirs coal-bed gas exploitation effective technical way " literary composition thinks that improving the infiltrative unique effective way of hyposmosis coal seam reservoirs is make coal seam pressure relief.Boring both sides hydraulic slotted liner technique, as publication zl03122734.1 and zl200910182119.4, proposes to form the flat slot that has certain depth, for improving reservoir permeability and Prevention against coal and gas blasting in boring both sides horizontal direction.This technology regards isotropic rock mass as coal and rock, does not consider the design feature of coal and rock, and especially the depositional fabric feature (as bedding and hugger) of coal and rock and dirt band are on the impact of coal seam permeability.Generally grow in China coal seam and have 1 ~ 3 layer of dirt band, dirt band thickness 140 ~ 500mm, even 1m can be reached, lateral deposition is stablized, continuity is good, dirt band is charcoal mudrock, permeability is extremely low, water-swellable and easily deformable, the vertical crack that horizontal slot release produces may not extend very well when running into coal seam dirt band, simultaneously, seat earth is mud stone, and there is obvious dilatancy, the height of horizontal slot generally only has 20-30mm, when slot width is larger, along with the distortion in coal seam later stage, under the synergy of the upward force that slot produces at top covering rockmass gravity and base plate pucking, crimp to a certain extent, permeability lowers, in addition, complete horizontal slot, must be directed to nozzle carrying out horizontal, difficulty of construction is very large, and from existing open source information, horizontal slot first in coal seam, plays a boring, and then adopt special slotting device to utilize the coal body of high-pressure water jet to boring both sides to cut, as coal seam collapse hole, slotting device is difficult to enter again, cannot creep into and once complete with slot.
Summary of the invention
The present invention overcomes the deficiency that prior art exists, technical problem to be solved is for providing a kind of design feature taking into full account coal and rock, make concordant long drilled holes borehole wall stress dispersion, influence basin large, the concordant long drilled holes slot hole flushing integration extraction coal bed gas method that extraction efficiency is high.
In order to solve the problems of the technologies described above, the technical solution used in the present invention is: concordant long drilled holes slot hole flushing integration extraction coal bed gas method, comprises the following steps:
A, in the coal seam of intending coal-bed gas extract, bore the concordant long drilled holes of desired depth by drilling tool with rig;
B, move back get into drilling tool by top pressure time, in drilling tool, pass into the water under high pressure of 25 ~ 35MPa, drilling tool original place rotate, on vertical concordant long drilled holes axial plane, form a vertical large fracture by high-pressure water jet;
C, continue to move back brill, moving back in drill-through journey, reduce hydraulic pressure to 10 ~ 15MPa, rinse the hole wall of concordant long drilled holes, drilling tool stops after stepping back a segment distance, to construct a new vertical large fracture by the method in step b;
D, repetition step c, make concordant long drilled holes to be formed multiple vertical large fracture, and the vertical large fracture being positioned at position, concordant long drilled holes aperture has a setpoint distance, with the sealed borehole length making the position, aperture of concordant long drilled holes leave at least 5m apart from aperture;
E, stopping high-pressure water jet, exit drilling tool, and with sealing material to concordant long drilled holes sealing of hole;
F, use coal bed gas extraction system extraction coal bed gas.
Further, repeat step a ~ f, in coal seam, form plural concordant long drilled holes, the vertical large fracture in adjacent concordant long drilled holes is staggered or aligned flush along concordant long drilled holes depth direction.
The width of described vertical large fracture is 20-40mm, and radius is 500-1000mm.
It is once 8 ~ 10m that described drilling tool is stepped back, and the spacing namely between adjacent two vertical large fractures is 8 ~ 10m.
Be mixed with 70 ~ 120 object quartz sands in described water under high pressure, described quartz sand volume in water under high pressure and quartz sand mixture accounts for 5%.
The distance being positioned at the vertical large fracture distance aperture at position, concordant long drilled holes aperture in described steps d is 15 ~ 20m.
The drilling speed degree that moves back in described step c, steps d, step e is 1 ~ 3m/min.
On described coal seam, the below of concordant long drilled holes, bore drainage hole obliquely, the aperture place of drainage hole is provided with dewatering installation, the gradient of drainage hole axis is not less than 5 ‰ ~ 8 ‰, distance between drainage hole and concordant long drilled holes axis is determined with maximum effect relaxation zone of vertical large fracture, or is 0.5 ~ 3 times of vertical large fracture diameter.
Described drainage hole is constructed along construction of bottom plates or in base plate in coal seam.
When same vertical plane being furnished with multiple concordant long drilled holes, only in the concordant long drilled holes arranged beneath drainage hole near base plate.
The mechanism that the present invention improves coal seam permeability is as follows.
The hole flushing of concordant long drilled holes water jet is exactly by carrying out cutting large fracture to the vertical plane of vertical drilling axis and after forming shallow table crack to hole wall hole flushing with the vertical large fracture extraction coal bed gas method of cutting, the vertical large fracture conducting bedding of coal petrography layering, the coal petrography section separated between two vertical large fractures, from coal-bed methane seepage cylindrical coordinates equation (1):
In formula: p-pore pressure, K
r-hole diameter to transmission coefficient, K
z-borehole axial transmission coefficient, n-degree of porosity, a, b-absorption constant, e-cubic deformation, using drilling axis as z-axis, hole diameter disobeys θ change to for r to, pore pressure.
Before the vertical large fracture of cutting, the passage of coal-bed methane seepage is centered by drilling axis, and the coal bed gas around in coal and rock is to seepage flow in boring, and boring is the extraction gas well of a Radial Flow Through Porous Media, for coal bed gas concordant long drilled holes, only has first 2, Section 3
after carrying out the vertical large fracture of cutting to boring, the passage of coal-bed methane seepage becomes both direction, and first as hereinbefore; Second along the migration of bed plane direction, coal seam, after arriving vertical large fracture, then flows into extraction borehole by vertical large fracture for being parallel to drilling axis, from percolation equationk (1), and the Section 3 of coal-bed methane seepage equation
increase by one.
The permeability in coal seam has following characteristics: 1, coal seam longitudinal direction is split by roof and floor, the stratiform organic rock combined by the different order of glance coal, semibright coal, semidull coal, dull coal and coal seam dirt band.From glance coal ~ semibright coal ~ semidull coal ~ dull coal, hugger density reduces gradually; 2, the coal sample of same coal seam, under identical condition, the permeability of parallel bedding coal sample is greater than the permeability of vertical stratification coal sample, and its difference is roughly at about 1 ~ 10 times; 3, lithostructure is the coal seam reservoirs double-porosity system structure be made up of matrix pores system and fissure system, coal-based is relative impervious to gas and water, coal cleat system in coal seam is then the central core of circulation of fluid neuron network and output, the permeability in coal seam mainly controls by coal seam hugger, is crucially one of the quality factor determining coal seam permeability; 4, hugger is divided into face cleat and end hugger, they are mutually substantially vertical, and all orthogonal with coal seam aspect or steep angle is crossing, and it mainly appears in glance coal and vitrain band, face cleat is that a group in coal extends longer main hugger, is the central core of circulation of coal bed gas infiltration; End hugger is one group of secondary hugger in coal, grows between two face cleats, and it extends the restriction by face cleat.
According to the infiltrative feature of above lithostructure, after the vertical large fracture of drilling construction, in the plane influence basin of vertical large fracture, vertical large fracture has linked up bedding and the face cleat of different coal petrography layering, especially coal seam dirt band has been cut off to the obstruct to different coal petrography layering coal bed gas migration, change the gas flow pattern of coal seam extraction boring, make the Radial Transport mode that original extraction borehole circumference is single, after the vertical large fracture of construction, become Radial Transport and to migrate two kinds of modes along coal petrography layering bedding, make the migration of coal bed gas in coal seam as far as possible along coal seam bedding or crack maximum direction migration, optimize coal bed gas permeation pathway,---hugger---hole the coal bed gas extraction passage of two kinds by bedding---vertical large fracture---to establish boring radial diffusion and matrix of coal hole, improve coal seam permeability, improve single hole unit interval coal bed gas pumping volume and drainage efficient, gas drainage results is made to reach optimum state, achieving with geological theory is the coal bed drilling method for arranging instructed.
The present invention compared with prior art has following beneficial effect.
1, the invention provides a kind of concordant long drilled holes slot hole flushing integration extraction coal bed gas method, achieve the combination of concordant long drilled holes and Waterjets cutting technology, fully combine rate of penetration in concordant long drilled holes coal seam fast, single hole length is long and water jet cutting is little to reservoir damage, can realize the advantage of directional cutting.
2, the present invention passes through coal seam depositional fabric, hugger feature and the distribution of coal seam dirt band are to the infiltrative impact analysis of coal bed gas, coal bed gas extraction borehole is arranged on the anisotropic basis of coal petrography permeability targetedly taking into full account, by vertical large fracture of constructing in the vertical plane of vertical concordant long drilled holes axis, link up the contact between the different layering bedding of coal petrography and hugger, especially the obstruct that coal seam dirt band is migrated to different coal petrography layering coal bed gas has been linked up, change the gas flow pattern of coal seam extraction boring, make the Radial Transport mode that original extraction borehole circumference is single, construct and to have become Radial Transport after vertical large fracture and to migrate two kinds of modes along coal petrography layering bedding, make the migration of coal bed gas in coal seam as far as possible along coal seam bedding or crack maximum direction migration, optimize coal bed gas permeation pathway,---hugger---bedding---vertical large fracture---the two kinds of coal bed gas extraction passages of boring that establish boring radial diffusion and matrix of coal hole, improve coal seam permeability, improve single hole unit interval coal bed gas pumping volume and drainage efficient, gas drainage results is made to reach optimum state, achieving with geological theory is the coal bed drilling method for arranging instructed.
3, the vertical large fracture discharge section coal body in the present invention, form larger relief area, destroy the inner original balancing of stresses in coal seam, geostatic stress is caused to redistribute, coal seam is along plane propagation direction generation release (geostatic stress reduction), distortion, expansion, thus open under making the effect of original vertical closed or semi-enclosed hugger stretching force in the horizontal direction, extend and conducting, expand the influence basin of vertical hugger, and extraction later stage vertical large fracture should not close.
4, the present invention almost can not consider that down-hole cuts off the relation between orientation and drilling axis, and the combination and the face that realize vertical large fracture and drilling axis cut off, effective UNICOM of bedding.
5, the present invention adopts the water jet of certain pressure to the hole flushing of boring vertical large fracture interval section hole wall, can slacken boring drilling process in construction and drilling fluid to the pollution of hole wall, Qian Biao crack, hole wall top layer can be increased simultaneously, slacken boring " bottle stopper effect " around, increase effective radius of influence and the drilling-draining rib exposed area of boring, improve hole wall gas permeability of coal seam, improve drainage efficient.
6, the present invention arranges drainage hole separately below the concordant long drilled holes near seat earth, achieve draining to be separated with exhaust, and be communicated with due to maximum effect relaxation zone of drainage hole with the vertical large fracture of concordant long drilled holes, the ponding of concordant long drilled holes particularly in vertical large fracture lower half plane can be discharged effectively fast, make coal bed gas reach Quick drainage step-down and desorb occurs, improve drainage efficient.
Accompanying drawing explanation
Below in conjunction with accompanying drawing, the present invention will be further described in detail.
Fig. 1 is the section structure schematic diagram by coal seam after concordant long drilled holes slot hole flushing integration extraction coal bed gas method of the present invention construction.
Fig. 2 is the lateral view of Fig. 1.
Fig. 3 is the column legend of Fig. 1, Fig. 2.
Fig. 4 be by have multiple concordant long drilled holes in coal seam after method disclosed by the invention construction and vertical large fracture in adjacent concordant long drilled holes along structural representation during concordant long drilled holes depth direction aligned flush.
Fig. 5 be by have multiple concordant long drilled holes in coal seam after method disclosed by the invention construction and vertical large fracture in adjacent concordant long drilled holes is staggered along concordant long drilled holes depth direction time structural representation.
Fig. 6 is the method for arranging schematic diagram of drainage hole when arranging two or more concordant long drilled holes after constructing by method disclosed by the invention in same vertical plane.
Fig. 7 is that in the inventive method, brill used cuts the structural representation washing integrated drilling tool.
Fig. 8 is the A-A profile of Fig. 4.
Fig. 9 is the B-B profile of Fig. 4.
Figure 10 is the enlarged drawing at C place in Fig. 5.
In figure: 1 is coal seam, 2 is concordant long drilled holes, 3 is vertical large fracture, 4 is top connection, 5 is housing, 6 is core barrel, 7 is axle, 8 is drill bit, 9 is upper shell, 10 is housing, 11 is lower casing, 12 is nozzle, 13 is the first spring, 14 is annular protrusion, 15 is tube connector, 16 is pressure cap, 17 is the second spring, 18 is overflow valve, 19 is connector, 20 is filter screen, 21 is projection, 22 is coal bed gas drainage roadway, 23 is releasing pipe, 24 is drilling and sealing section, 25 is glance coal, 26 is semibright coal, 27 is semidull coal, 28 is dull coal, 29 is dirt band, 30 is top board, 31 is base plate, 32 is drainage hole.
Detailed description of the invention
As shown in Figure 1, Figure 2, Figure 3 shows, concordant long drilled holes slot hole flushing integration extraction coal bed gas method of the present invention, comprises the following steps:
A, in the coal seam 1 of intending coal-bed gas extract, bore the concordant long drilled holes 2 of desired depth by drilling tool with rig;
B, move back get into drilling tool by top pressure time, in drilling tool, pass into the water under high pressure of 25 ~ 35MPa, drilling tool original place rotate, on vertical concordant long drilled holes 2 axial plane, form a vertical large fracture 3 by high-pressure water jet;
C, continue to move back brill, moving back in drill-through journey, reduce hydraulic pressure to 10 ~ 15MPa, rinse the hole wall of concordant long drilled holes 2, drilling tool stops after stepping back a segment distance, to construct a new vertical large fracture 3 by the method in step b;
D, repetition step c, make concordant long drilled holes 2 to be formed multiple vertical large fracture 3, and the vertical large fracture 3 being positioned at position, concordant long drilled holes 2 aperture has a setpoint distance apart from aperture, with the sealed borehole length making the position, aperture of concordant long drilled holes 2 leave at least 5m;
E, stopping high-pressure water jet, exit drilling tool, and with sealing material to concordant long drilled holes 2 sealing of hole;
F, use coal bed gas extraction system extraction coal bed gas.
Further, as shown in Figure 4, Figure 5, repeat step a ~ f, in coal seam 1, form plural concordant long drilled holes 2, the vertical large fracture 3 in adjacent concordant long drilled holes 2 is staggered or aligned flush along concordant long drilled holes 2 depth direction.
As shown in Figure 1, Figure 2, Figure 6 shows, in order to draining, on described coal seam 1, the below of concordant long drilled holes 2, bore drainage hole 32 obliquely, the aperture place of drainage hole 32 is provided with dewatering installation, and the gradient of drainage hole 32 axis is not less than 5 ‰ ~ 8 ‰, distance between drainage hole 32 and concordant long drilled holes 2 axis is determined with maximum effect relaxation zone of vertical large fracture 3, or is 0.5 ~ 3 times of vertical large fracture 3 diameter.
Described drainage hole 32 is constructed along base plate 31 or is constructed in base plate 31 in coal seam 1.
When same vertical plane being furnished with multiple concordant long drilled holes 2, only in the concordant long drilled holes 2 arranged beneath drainage hole 32 near base plate 31.
Described drainage hole 32 is common boring, and drainage hole 32 is linked up with the Effect of Fissure band of the concordant long drilled holes 2 near coal seam 1 base plate 31, and drainage hole 32 will keep water outlet position minimum, is beneficial to the discharge of ponding.
The desirable φ 75 ~ 100mm of diameter of described concordant long drilled holes 2.
The width of described vertical large fracture 3 is 20-40mm, and radius is 500-1000mm; At the scene, to the concordant long drilled holes 2 in coal seam 1 construct vertical large fracture 3 time, the flow of high-pressure water jet is 120 ~ 200L/min, the rotary speed of drilling tool is 50 ~ 100r/min, the clipping time of vertical large fracture 3 can be determined according to aperture return slag situation, observes when aperture return slag diminishes and stops cutting, be generally 10 ~ 20min, then reduce hydraulic pressure, at the uniform velocity rotate and move back brill.
Spacing in a concordant long drilled holes 2 between adjacent two vertical large fractures 3 was comprehensively determined according to coal seam 1 coal bed gas content, coal bed gas pressure, drilling-draining time, according to existing underground coal mine actual conditions, generally can be taken as 8 ~ 10m, namely described drilling tool is stepped back is once 8 ~ 10m.
The inventive method can according to coal seam 1 hardness and dirt band 29 number of plies, thickness and distribution situation, abrasive material is increased in described water under high pressure, abrasive material adopts 70 ~ 120 order quartz sands, quartz sand volume in water under high pressure and quartz sand mixture accounts for 5%, form high-pressure sand blast water jet, increase vertical large fracture 3 radius.
The vertical large fracture 3 being positioned at position, concordant long drilled holes 2 aperture in described steps d is 15 ~ 20m apart from the distance in aperture.
The drilling speed degree that moves back in described step c, steps d, step e is 1 ~ 3m/min.
As shown in Figure 1, coal seam 1 between top board 30 and base plate 31 is made up of one or more layers glance coal 25, semibright coal 26, semidull coal 27, dull coal 28 and dirt band 29, wherein, be distributed with again various hugger, vertical large fracture 3 in the method disclosed in the present is conducting different beddings and hugger well, improves the permeability in coal seam 1.
As shown in Fig. 7, Fig. 8, Fig. 9, Figure 10, a kind of brill used in the methods of the invention cuts washes integrated drilling tool, comprise top connection 4, housing 5, core barrel 6, axle 7 and drill bit 8, described housing 5 is formed by upper shell 9, housing 10 and lower casing 11 are end to end successively, top connection 4 is connected with upper shell 9, and top connection 4, upper shell 9, housing 10 and lower casing 11 inside all have axially extending bore, the diameter of described housing 10 and the inner axially extending bore of lower casing 11 is greater than the diameter of top connection 4 and the inner axially extending bore of upper shell 9; One end of core barrel 6 is fixedly set in the inside of shell 9, the other end of core barrel 6 is positioned at housing 10 inside and core barrel 6 is provided with one or more radial direction through hole as connector 19 near this end end, position corresponding with connector 19 on described core barrel 6 on housing 10 also all has radial direction through hole, install in radial direction through hole and make seam nozzle 12, core barrel 6 is positioned at the end sealing of housing 10 inside and sealing has hole; One end movable set of axle 7 is in the inside of housing 10, and the other end of axle 7 stretches out outside lower casing 11 and is connected with drill bit 8, and be installed with the first spring 13 between the part that axle 7 is stretched out and lower casing 11, axle 7 inside has axially extending bore; One end that core barrel 6 is positioned at housing 10 inside is sleeved on the axially extending bore of axle 7, axle 7 inside is provided with annular protrusion 14, one end of tube connector 15 is connected on annular protrusion 14, the other end of tube connector 15 connects through the Kong Houyu pressure cap 16 on core barrel 6 end sealer, be installed with the second spring 17 between core barrel 6 end sealer and axle 7 annular protrusion 14, the sidewall of described tube connector 15 have multiple microscler fluid through-hole excessively.
The center of described pressure cap 16 is provided with the overflow valve 18 being communicated with core barrel 6 inside and axle 7 inside.
The inwall of described housing 10 is provided with multiple axial notch, and the position that axle 7 outer wall is corresponding with described groove is provided with projection 21, and described projection 21 is arranged in corresponding groove separately.
The end outer wall that described axle 7 is arranged in housing 10 is provided with boss, and the boss of described axle 7 end is coordinated by taper surface with the step on the inwall of housing 10.
Connector 19 place on described core barrel 6 is provided with filter screen 20, and described filter screen 20 is positioned on the inwall of core barrel 6.
Described nozzle 12 can arrange 1 ~ 3, and the diameter of nozzle 12 is 1 ~ 3mm.
Above-mentioned brill cuts the course of work of washing integrated drilling tool: in the process that drill bit 8 normally creeps into forward, drill bit 8 is subject to the pressure on top surface creeping into rock mass, promotion axle 7 extrudes the first spring 13 and the second spring 17 bounces back, the inner chamber of tube connector 15 centripetal canals 6 between axle 7 and core barrel 6 moves, the connector 19 core barrel 6 being used for be communicated with housing 10 is closed by axle 7 inwall, tube connector 15 extend in core barrel 6, core barrel 6 and the conducting of axle 7 inner chamber, drilling fluid enters the inner chamber of axle 7 by core barrel 6, flowed out by the outlet before drill bit 8, increase hydraulic pressure, drill bit 8 creeps into forward, creep into neck eye, the nozzle 12 now making seam for borehole sidewall is in closure state all the time.
After creeping into set depth, carry out according to schedule moving back brill operation, when moving back the vertical large fracture 3 getting into certain position manufacture vertical drilling axis, drill bit 8 dead ahead has formed neck eye, drill bit 8 is no longer pressed by the top of creeping into rock mass, first spring 13 and the second spring 17 jointly promote axle 7 and move forward, tube connector 15 between core barrel 6 and axle 7 exits the inner chamber of core barrel 6, passage between core barrel 6 and axle 7 inner chamber closes by the pressure cap 16 on tube connector 15 under the effect of the second spring 17, connector 19 simultaneously on core barrel 6 is opened, then hydraulic pressure is increased, drilling fluid enters cavity between core barrel 6 and housing 10, water jet is formed again by nozzle 12, in drilling rod rotary course, form the vertical large fracture 3 of vertical oblateness of one fixed width and certain depth.
In the above-mentioned course of work, load transfer process is: creep into neck at the moment, is connected with rear portion drilling rod by top connection 4, and the pressure of the drill reaches drill bit 8 through upper shell 9, housing 10, lower casing 11, axle 7; Creep into end to move back in drill-through journey and do not transmit the pressure of the drill.
In the above-mentioned course of work, moment of torsion transmittance process is: creep into neck at the moment, is connected with rear portion drilling rod by top connection 4, and the pressure of the drill through upper shell 9, housing 10, reach axle 7 by the projection 21 in axle 7, then reaches drill bit 8 by axle 7; When moving back brill, through upper shell 9, housing 10, drive the nozzle 12 of housing 10 sidewall to rotate and form vertical large fracture 3 or drill hole wall is rinsed.
Creep into and lead at the moment drilling liquid flow flowing mode to be: drilling fluid by tube connector 15 sidewall crosses fluid through-hole by core barrel 6, is entered the inner chamber of axle 7, flowed out by the outlet before drill bit 8 through axle 7 annular protrusion 14 middle through-hole.
When moving back brill, drilling liquid flow flowing mode is: drilling fluid enters cavity between core barrel 6 and housing 10 by core barrel 6 by connector 19, is then sprayed by the nozzle 12 of housing 10 tube wall.If hydraulic pressure exceedes the hydraulic pressure upper limit, the overflow valve 18 being arranged on pressure cap 16 center will be opened, and a part of liquid is by overflow valve 18, the inner chamber of axle 7 is entered through tube connector 15, flowed out by the outlet before drill bit 8 and implement pressure release, time below the pressure recover upper limit, overflow valve 18 closes.
Embodiment 1
Concordant long drilled holes slot hole flushing integration extraction coal bed gas method, with reference to Fig. 1, illustrated in Figure 2.Coal seam, somewhere 1 thickness is 3m, tunnel length 800m, in the middle part of coal bed gas drainage roadway 22 work plane of coal seam 1 between two-layer dirt band 29, adopts km rig to creep into concordant long drilled holes 2 in pre-digging laneway direction, concordant long drilled holes 2 diameter phi 96mm.After boring reaches desired depth, with clean water drilling rod passage, move back brill, at vertical large fracture 3 design attitude of foot of hole first, drilling rod original position rotates, increase hydraulic pressure, seam nozzle 12 is made in unlatching, the vertical large fracture cutter sweep of applying high voltage water jet, vertical large fracture 3 is cut at vertical concordant long drilled holes 2 axial plane, make the desirable 25 ~ 35MPa of seam pressure, flow 120 ~ 200L/min, clipping time 10 ~ 20min, rotary speed 60r/min, in addition, can according to coal seam 1 hardness and dirt band 29 number of plies, thickness and distribution situation, abrasive material is increased to water jet, abrasive material adopts 70 ~ 110 order quartz sands, quartz sand volume in water under high pressure and quartz sand mixture accounts for about 5%, form high-pressure sand blast water jet, increase vertical large fracture 3 radius.On-the-spot vertical large fracture 3 can be determined according to aperture return slag situation clipping time, and when observation aperture return slag diminishes, reduce hydraulic pressure, stop vertical large fracture 3 to cut, complete first vertical large fracture 3, the diameter of vertical large fracture 3 is about 1500mm.Reduce hydraulic pressure, at the uniform velocity rotate and move back brill, moving back drilling speed rate is 1 ~ 3m/min, Stress control is at about 15MPa, Tui Zuan limit, limit adopts water jet to rinse to concordant long drilled holes 2 hole wall, after moving back brill 8 ~ 10m, arrive second and make seam position, drilling rod original position rotates, again water flow pressure is increased, carry out the construction of second vertical large fracture 3, construction parameter is the same, after completing second vertical large fracture 3 thus, step-down, Tui Zuan limit, limit is rinsed concordant long drilled holes 2 hole wall, the rest may be inferred, according to vertical large fracture 3 spacing of design, to construct successively from the inside to surface all vertical large fracture 3 and rinse all hole walls except the sealing of hole section of aperture, until complete last vertical large fracture 3 apart from 15m place, aperture, releasing pipe 23 is laid in aperture, sealing of hole is carried out to drilling and sealing section 24, sealed borehole length is greater than 5 ~ 8m, and releasing pipe 23 is connected with down-hole drainage system, complete the construction that a concordant long drilled holes spaced radial cuts the boring of vertical large fracture.Then below concordant long drilled holes 2, press the gradient construction drainage boring obliquely 32 of 5 ‰, distance between drainage hole 32 and concordant long drilled holes 2 axis is 1.5d (d is the diameter of vertical large fracture 3), after drainage hole 32 has been constructed, at aperture place, dewatering installation is installed.After all engineering constructions complete, debugging, utilizes the coal bed gas of down-hole draw-off pump station to this extraction boring influence area to implement extraction.
Embodiment 2
Adopt multiple parallel concordant long drilled holes 2 spaced radial to cut vertical large fracture 3 method extraction coal bed gas, arrange boring and vertical large fracture 3 with reference to figure 3 and mode illustrated in Figure 4.Group coal seam 1, Shanxi, somewhere thickness is 3m, vertical large fracture 3 diameter is about φ 2000mm, concordant long drilled holes 2 axis is arranged in the middle part of coal seam 1, spacing between two vertical large fractures 3 is between 8 ~ 10m, and the spacing of concordant long drilled holes 2 is different according to the arrangement mode difference of large fracture 3 vertical in adjacent concordant long drilled holes 2.In adjacent concordant long drilled holes 2, vertical large fracture 3 is by rectangular arrangement, time namely along concordant long drilled holes 2 depth direction aligned flush, and the desirable 3 ~ 5m of spacing (see Fig. 3) of concordant long drilled holes 2; In adjacent concordant long drilled holes 2, vertical large fracture 3 is by triangular arrangement, when being namely staggered along concordant long drilled holes 2 depth direction, and the desirable 2m of spacing (see Fig. 4) of concordant long drilled holes 2.According to above parameter, km rig is adopted to form concordant long drilled holes 2, concordant long drilled holes 2 is crept into by drilling design track at coal seam 1 coal bed gas drainage roadway 22, and by being interposed between concordant long drilled holes 2 radial direction construction vertical large fracture 3 and to hole wall hole flushing between design, the concrete construction method of concordant long drilled holes 2 and vertical large fracture 3, with embodiment 1, completes the construction that a concordant long drilled holes spaced radial cuts the boring of vertical large fracture.Then below concordant long drilled holes 2, press the gradient construction drainage boring obliquely 32 of 5 ~ 8 ‰, distance between drainage hole 32 and concordant long drilled holes 2 axis is 2d (d is the diameter of vertical large fracture 3), drainage hole 32 is arranged in base plate 31, after drainage hole 32 has been constructed, at aperture place, dewatering installation is installed.And first hole 2.5 ~ 3m place, interval (rectangular cloth hole) or and first 2m place, interval that holes (triangle cloth hole), complete after the same method second concordant long drilled holes spaced radial cut vertical large fracture boring construction.Repetition like this, complete all boring successively, until complete the whole concordant long drilled holes 2 of extraction stope and vertical large fracture 3, lay releasing pipe 23 in each concordant long drilled holes 2 aperture of having completed, sealing of hole is carried out to drilling and sealing section 24, releasing pipe 23 is connected with down-hole drainage system.Meanwhile, construction drainage boring 32 all as stated above below each concordant long drilled holes 2.After all engineering constructions complete, debugging, utilizes the coal bed gas of down-hole draw-off pump station to this extraction boring influence area to implement extraction.
Embodiment 3
When coal seam thickness is 5 ~ 6m, can arrange 2 ~ 3 concordant long drilled holes 2 at same vertical plane higher slice, with reference to figure 6, on horizontal plane, the arrangement of concordant long drilled holes 2 can refer to Fig. 4 or Fig. 5.Group coal seam 1, Shanxi, somewhere thickness is 5.8m, same vertical plane arranges two concordant long drilled holes 2, spacing is 2.5m, spacing on horizontal plane between adjacent concordant long drilled holes 2 is 5m, in concordant long drilled holes 2, the diameter of vertical large fracture 3 is about φ 2000mm, spacing between two vertical large fractures 3 is 8 ~ 10m, concordant long drilled holes 2 and on the construction method of vertical large fracture 3 with embodiment 1.Then below the concordant long drilled holes 2 of each close base plate 31, press the gradient construction drainage boring obliquely 32 of 5 ‰, distance between drainage hole 32 and concordant long drilled holes 2 axis is 1.5 ~ 2d (d is the diameter of vertical large fracture 3), drainage hole 32 is arranged in base plate 31, after drainage hole 32 has been constructed, at aperture place, dewatering installation is installed.Constructed after all concordant long drilled holes 2 and drainage hole 32, concordant long drilled holes 2 and down-hole draw-off pump station pipeline UNICOM, drainage hole 32 and discharge pipe line UNICOM, debug, debugged and can carry out coal bed gas extraction.
Claims (9)
1. concordant long drilled holes slot hole flushing integration extraction coal bed gas method, is characterized in that comprising the following steps:
A, in the coal seam (1) of intending coal-bed gas extract, bore the concordant long drilled holes (2) of desired depth by drilling tool with rig;
B, move back get into drilling tool by top pressure time, in drilling tool, pass into the water under high pressure of 25 ~ 35MPa, drilling tool original place rotate, on vertical concordant long drilled holes (2) axial plane, form a vertical large fracture (3) by high-pressure water jet;
C, continue to move back brill, moving back in drill-through journey, reduce hydraulic pressure to 10 ~ 15MPa, rinse the hole wall of concordant long drilled holes (2), drilling tool stops after stepping back a segment distance, to construct a new vertical large fracture (3) by the method in step b;
D, repetition step c, make the multiple vertical large fracture (3) of the upper formation of concordant long drilled holes (2), and the vertical large fracture (3) being positioned at concordant long drilled holes (2) position, aperture has a setpoint distance, with the sealed borehole length making the position, aperture of concordant long drilled holes (2) leave at least 5m apart from aperture;
E, stopping high-pressure water jet, exit drilling tool, and with sealing material to concordant long drilled holes (2) sealing of hole;
F, use coal bed gas extraction system extraction coal bed gas;
On described coal seam (1), the below of concordant long drilled holes (2), bore drainage hole (32) obliquely, the aperture place of drainage hole (32) is provided with dewatering installation, the gradient of drainage hole (32) axis is not less than 5 ‰ ~ 8 ‰, distance between drainage hole (32) and concordant long drilled holes (2) axis is determined with maximum effect relaxation zone of vertical large fracture (3), or is 0.5 ~ 3 times of vertical large fracture (3) diameter.
2. concordant long drilled holes slot hole flushing integration extraction coal bed gas method according to claim 1, it is characterized in that: repeat step a ~ f, in coal seam (1), form plural concordant long drilled holes (2), the vertical large fracture (3) on adjacent concordant long drilled holes (2) is staggered or aligned flush along concordant long drilled holes (2) depth direction.
3. concordant long drilled holes slot hole flushing integration extraction coal bed gas method according to claim 1 and 2, is characterized in that: the width of described vertical large fracture (3) is 20-40mm, and radius is 500-1000mm.
4. concordant long drilled holes slot hole flushing integration extraction coal bed gas method according to claim 1 and 2, it is characterized in that: it is once 8 ~ 10m that described drilling tool is stepped back, the spacing namely between adjacent two vertical large fractures (3) is 8 ~ 10m.
5. concordant long drilled holes slot hole flushing integration extraction coal bed gas method according to claim 1 and 2, it is characterized in that: be mixed with 70 ~ 120 object quartz sands in described water under high pressure, described quartz sand volume in water under high pressure and quartz sand mixture accounts for 5%.
6. concordant long drilled holes slot hole flushing integration extraction coal bed gas method according to claim 1 and 2, is characterized in that: the distance being positioned at vertical large fracture (3) the distance aperture at concordant long drilled holes (2) position, aperture in described steps d is 15 ~ 20m.
7. concordant long drilled holes slot hole flushing integration extraction coal bed gas method according to claim 1 and 2, is characterized in that: the drilling speed degree that moves back in described step c, steps d, step e is 1 ~ 3m/min.
8. concordant long drilled holes slot hole flushing integration extraction coal bed gas method according to claim 1, is characterized in that: described drainage hole (32) is constructed along base plate (31) or constructed in base plate (31) in coal seam (1).
9. concordant long drilled holes slot hole flushing integration extraction coal bed gas method according to claim 1 and 2, it is characterized in that: when same vertical plane being furnished with multiple concordant long drilled holes (2), only in concordant long drilled holes (2) the arranged beneath drainage hole (32) near base plate (31).
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| CN103696800B (en) * | 2013-12-18 | 2016-03-23 | 中国矿业大学 | A kind of brill cuts pressure and takes out method |
| CN106089289B (en) * | 2016-06-08 | 2018-12-21 | 中国矿业大学 | Alternately protected type stope concordant drilling hydraulic flushing in hole makes cave construction method |
| CN107191187B (en) * | 2017-07-07 | 2019-11-05 | 中国中煤能源集团有限公司 | A kind of gob side entry retaining cuts top pressure relief method |
| CN108661697A (en) * | 2018-05-31 | 2018-10-16 | 中煤科工集团西安研究院有限公司 | Long drilled holes gas enhanced gas extraction method under the service well of ground |
| CN113756858B (en) * | 2021-09-30 | 2023-10-20 | 中煤科工集团重庆研究院有限公司 | Method for directional drilling Kong Bukong based on gas extraction under dim coal layering condition |
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| CN101403314B (en) * | 2008-11-18 | 2011-03-23 | 河南理工大学 | Coal mine down-hole drilling hydraulic fracturing anti-reflection mash gas extraction technique |
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