A kind of method for weakening coal seam tight roofTechnical field
Collapse roof weakening processing technology field the invention belongs to the hard difficulty in coal seam, be specifically a kind of reduction coal seam tight roofMethod.
Background technology
In China, preservation has a large amount of tight roof coal seams, the direct preservation of such top plate above coal seam or thinner thickness it is straightConnect top above, intensity is high, thickness is big, globality is strong, joint fissure agensis.Coal mining is caving when using tool pillar mining method or longwellWhen method is exploited, tight roof can be in the outstanding dew very large area in goaf without being caving, and first weighting and periodic weighting step pitch are big, to pressWhen produce impact of dynamic pressure, be easily damaged support, goaf area of suspension roof is up to thousands of, tens of thousands of square metres under serious conditions.In timeThe tight roof of the outstanding dew of processing, it is prevent top plate large area inbreak basic to reduce accumulation of energy and reduce top plate height of dropMethod.
The hard difficulty in colliery collapses the improvement of top plate, is always the more important research contents in coal mine roof plate CONTROL OF STRATA MOVEMENT field.Processing tight roof be mainly by take overhead caving measure change top plate mechanical condition, and then weaken top plate intensity andIt is whole to destroy the integrality of top plate, goaf top plate is layered and is caving by several times, shorten first weighting and periodic weighting step pitch, fromAnd ground pressure strength is reduced, reach and hard difficulty is reduced or eliminated collapses the purpose that top plate is endangered working face extraction.Processing coal both at home and abroadThe method of ore deposit tight roof is more based on blasting procedure, supplemented by underground water-injection pressure break reduction method.Blasting is simple, but quantitiesGreatly, subsurface environment is polluted, and for highly gassy mine, potential safety hazard also be present.Underground fracture water filling weakens the application of methodAlso there is its limitation, main cause is that water filling discharge capacity is limited, and pressure break and atenuator region are limited in scope.Coal adopts country altogether with coal bed gasKey lab develops correlation technique.
The content of the invention
The present invention is in order to solve in actual recovery process, the outstanding dew of tight roof large area, it is difficult to spontaneous caving, be cavingIt is mostly afterwards large area caving, its coverage is larger, ore deposit can be caused to shake under serious conditions, and accidental pollution event accident now is directAffect the problem of the normal of mining area is with safety in production, there is provided a kind of method for weakening coal seam tight roof.
The present invention takes following technical scheme：A kind of method for weakening coal seam tight roof, is comprised the following steps that,
1）Drilling well is set：
Tunnelling speed under the strict surge well of well spacing, it is unaffected to down-hole mining before guarantee engineering construction, by hydraulic fracturingDrilling well, which is arranged in, cuts eye inward in the range of 200m, wells spacing 100-200m, considers that the engineering well later stage will carry out ground gas and take outPut, therefore drilling well arrangement selection is apart from the nearlyer side of return airway.
2）Ground drilling：
（1）The perforate of drilling well one uses Ф 311mm drill bit perforates, creeps into stablizing below basement rock, tripping in Ф 244.5mm surface pipesTo hole depth, the full sealing of cementing；
（2）The perforate of drilling well two is drilled into exposure coal seam using Ф 215.9mm drill bits and stops boring, after drilling well below back-up sand to tight roof,Tripping in Ф 139.7mm production casings conventional density well cementation, are waited after coagulating 72 hours to back-up sand sand face, survey cementing quality, pressure testing.
3）Chemolysis：
After completion, perforation is used to old top tight roof, after injecting chemical solution, closing well -36 hours 24 hours, ensures chemical solutionThe abundant corrosion of liquid is pushed up always, reduces stress concentration, while be beneficial to follow-up pressing crack construction.
4）Hydraulic fracturing：
To the old jacking row conventional hydraulic sand fracturing of well of constructing, injected and constructed using light sleeve pipe, it is desirable to Hydrodynamic support fracture half-lengthFor 100~130m.
5）Ground extraction：
Using Ф 114mm drill bits drilling wells to coal seam position, ground gas extraction equipment is installed to well head and carries out gas ground extraction.By that to vertical mining influence region gas ground extraction, gas can be avoided to concentrate release and goaf gas once largely to gushGo out, realize improvement and control to mining influence regional coal-seam gas.
Compared with prior art, the present invention can both give full play to emollescence of the chemical solution to tight roof rock, againHydraulic fracturing can be given full play to seam effect is made to Rock cutting, so that tight roof rock softening；On the one hand it is initially switched off in advance oldTop, top plate is weakened, weaken working face first weighting intensity；Another aspect pressure break weakening top coal, strengthen top coal gas permeability, make top coalIt is caving in time, avoids gas from concentrating release and goaf gas once to pour out.The beneficial effect of following five aspect can be obtained：
1) constraint of traditional coal seam tight roof processing method is broken through, complicated to geological structure, firm and thicker heavily fortified point can be realizedResist plate bump solution danger stubbornly.
2) to tight roof rock softening and crushed by chemistry and physical method comprehensive function, reduce bump windDanger.
3) after by chemical action softening rock, rock rupture pressure is advantageously reduced；Implement hydraulic fracturing again, more utilizeBeing smoothed out for construction, can reduce rock strength.
4) said from security standpoint, this method is a kind of aggressive regional precautionary measures, and purpose is more clear and definite.
5) old top tight roof is weakened by pressure break, strengthens top coal gas permeability, avoid gas from concentrating release and goaf wattThis once pours out, and reaching first mash gas transfinites the purpose of improvement.
Brief description of the drawings
Fig. 1 is drilling well plane of arrangement figure；
Fig. 2 is wellbore structure schematic diagram；
1- stops exploiting field, 2- working faces, 3- return airways, 4- drilling wells, 5- air intake lanes, the perforates of 6- mono-, the perforates of 7- bis-, 8- perforations in figure.
Embodiment
Below in conjunction with the accompanying drawing in the embodiment of the present invention, the technical scheme in the embodiment of the present invention is carried out clear, completeSite preparation describes, it is clear that described embodiment is only part of the embodiment of the present invention, rather than whole embodiments.It is based onEmbodiment in the present invention, those of ordinary skill in the art are obtained every other under the premise of creative work is not madeEmbodiment, belong to the scope of protection of the invention.
A kind of method for weakening coal seam tight roof, is comprised the following steps that,
1）Drilling well is set：
Hydraulic fracturing drilling well is arranged in and cuts eye inward in the range of 200m, wells spacing 100-200m, drilling well arrangement selection away fromFrom the nearlyer side of return airway.
2）Ground drilling：
（1）The perforate of drilling well one uses Ф 311mm drill bit perforates, creeps into stablizing below basement rock, tripping in Ф 244.5mm surface pipesTo hole depth, the full sealing of cementing；
（2）The perforate of drilling well two is drilled into exposure coal seam using Ф 215.9mm drill bits and stops boring, after drilling well below back-up sand to tight roof,Tripping in Ф 139.7mm production casings conventional density well cementation, are waited after coagulating 72 hours to back-up sand sand face, survey cementing quality, pressure testing.
3）Chemolysis：
After completion, perforation is used to old top tight roof, after injecting chemical solution, closing well -36 hours 24 hours, ensures chemical solutionThe abundant corrosion of liquid is pushed up always, reduces stress concentration, while be beneficial to follow-up pressing crack construction.
4）Hydraulic fracturing：
To the old jacking row conventional hydraulic sand fracturing of well of constructing, injected and constructed using light sleeve pipe, it is desirable to Hydrodynamic support fracture half-lengthFor 100~130m.
5）Ground extraction：
Using Ф 114mm drill bits drilling wells to coal seam position, ground gas extraction equipment is installed to well head and carries out gas ground extraction.
It is not easy, across the harm fallen, to ensure mine safety production to solve tight roof, breaks through the existing tight roof of mineProcessing method, propose ground drilling, handle tight roof by the way of injection chemical solution and waterpower sand fracturing are compound.I.e.According to colliery digging planning and progress, in the construction ground drilling well at a certain distance from tunnelling face, tight roof is injectedChemical solution simultaneously carries out fracturing engineering, in coal seam formed up to 100~130m crack so that concentrated stress be released orRedistribute, eliminate tight roof layer stress concentration.
Although the present invention is described in detail with reference to the foregoing embodiments, for those skilled in the art,It can still modify to the technical scheme described in foregoing embodiments, or which part technical characteristic is carried out etc.With replacing, within the spirit and principles of the invention, any modification, equivalent substitution and improvements made etc., this should be included inWithin the protection domain of invention.