CN106089291B - A kind of method for cooperateing with extraction to be caving the old dead zone of formula and lower coal seam coal bed gas - Google Patents

A kind of method for cooperateing with extraction to be caving the old dead zone of formula and lower coal seam coal bed gas Download PDF

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CN106089291B
CN106089291B CN201610453385.6A CN201610453385A CN106089291B CN 106089291 B CN106089291 B CN 106089291B CN 201610453385 A CN201610453385 A CN 201610453385A CN 106089291 B CN106089291 B CN 106089291B
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extraction
bed gas
horizontal well
coal bed
valve
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CN106089291A (en
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冯国瑞
李振
高强
张钰亭
杜献杰
白锦文
郭军
张玉江
康立勋
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Taiyuan University of Technology
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    • E—FIXED CONSTRUCTIONS
    • E21—EARTH DRILLING; MINING
    • E21F—SAFETY DEVICES, TRANSPORT, FILLING-UP, RESCUE, VENTILATION, OR DRAINING IN OR OF MINES OR TUNNELS
    • E21F7/00—Methods or devices for drawing- off gases with or without subsequent use of the gas for any purpose
    • E—FIXED CONSTRUCTIONS
    • E21—EARTH DRILLING; MINING
    • E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B21/00—Methods or apparatus for flushing boreholes, e.g. by use of exhaust air from motor
    • E21B21/16—Methods or apparatus for flushing boreholes, e.g. by use of exhaust air from motor using gaseous fluids
    • E—FIXED CONSTRUCTIONS
    • E21—EARTH DRILLING; MINING
    • E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
    • E21B43/006—Production of coal-bed methane
    • E—FIXED CONSTRUCTIONS
    • E21—EARTH DRILLING; MINING
    • E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
    • E21B43/12—Methods or apparatus for controlling the flow of the obtained fluid to or in wells
    • E21B43/121—Lifting well fluids
    • E—FIXED CONSTRUCTIONS
    • E21—EARTH DRILLING; MINING
    • E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
    • E21B43/16—Enhanced recovery methods for obtaining hydrocarbons
    • E21B43/164—Injecting CO2 or carbonated water
    • E—FIXED CONSTRUCTIONS
    • E21—EARTH DRILLING; MINING
    • E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
    • E21B43/25—Methods for stimulating production
    • E21B43/26—Methods for stimulating production by forming crevices or fractures
    • E—FIXED CONSTRUCTIONS
    • E21—EARTH DRILLING; MINING
    • E21F—SAFETY DEVICES, TRANSPORT, FILLING-UP, RESCUE, VENTILATION, OR DRAINING IN OR OF MINES OR TUNNELS
    • E21F16/00—Drainage

Abstract

The invention discloses a kind of method for cooperateing with extraction to be caving the old dead zone of formula and lower coal seam coal bed gas.This method is surveyed to mine first, from ground to old dead zone construction of bottom plates horizontal well, press-in carbon dioxide cleaning, carries out coal bed gas extraction；When coal bed gas unit interval extraction amount drops to Q120% ~ 40%, circulation, which stops taking out, reduces extraction pressure and the again process of extraction；When extraction amount drops to Q1Less than 20% when, inject carbon dioxide displacement and extraction again；When extraction amount is re-lowered to Q1Less than 20%, pressure break horizontal well and lower coal seam coal rock layer, carry out coal bed gas extraction；When extraction amount drops to Q2Less than 20% when, carry out supercritical carbon dioxide displacement；Extraction is until the Q that extraction amount drops to again210% when stop taking out.It the method achieve collaboration extraction to be caving the old dead zone of formula and close on the coal bed gas of girdle, cost-effective and extraction coal bed gas resource to greatest extent.

Description

A kind of method for cooperateing with extraction to be caving the old dead zone of formula and lower coal seam coal bed gas
Technical field
The present invention relates to a kind of method for cooperateing with extraction to be caving the old dead zone of formula and lower coal seam coal bed gas, belong to extraction coal bed gas Technical field.
Background technology
Because long-term industrialization is exploited, there is countless old dead zones numerous, area is huge in China.Only using Shanxi Province as Example, ended for the end of the year 2013, Shanxi Province shares more than 4700 and locates abandoned mine, and for old dead zone area up to 5000 square kilometres, these are old The excavation of dead zone be mostly using the relatively low old-fashioned blast-winning technology of recovery ratio, its coal mining rate typically 50%~ 60%, it is even lower, therefore above-mentioned old dead zone preservation considerable coal bed gas resource gas reserves, related data is shown only The old billion cubic meter of dead zone Coal bed gas project about 30 by taking Shanxi Province as an example.Gas is a kind of clean energy resource, to old dead zone residual coal The recovery energy of layer gas, it can effectively alleviate the insufficient situation of China's natural gas；Gas is as a kind of pernicious gas simultaneously, It is discharged into 21 times that caused greenhouse effects in air are carbon dioxide, therefore has to the methane drainage and utilization project of this part gas good Good economic benefit and environmental benefit.
Currently for old dead zone gas extraction primarily directed to the extraction of the old dead zone gas of single working face, its method is From ground, into old dead zone top fissure zone, construction ground drilling well is with the old dead zone gas of extraction, during such a method wellbore construction Difficulty of construction is big, accident rate is high, one-tenth porosity is low.And a ground pit shaft can only be directed to an old dead zone and carry out extraction, The methane output of extraction is low and cost is high.Chinese patent CN105114038A discloses one kind and relies on supercritical CO2Jet pressure Split the method for the adjacent old old dead zone gas of empty interval coal column extraction same level two；Chinese patent CN104696006A is disclosed A kind of method for penetrating the old old dead zone remnants coal bed gas of dead zone abandoned coal pillar extraction multilayer of multilayer；The above method is vertical shaft extraction Multiple old dead zone gas are made that important exploration；
However, above-mentioned patent has that landing ground vertical drilling is small with coalbed methane reservoir contact surface, extraction is limited in scope etc. and asked Topic, while above-mentioned patent is to retain coal bed gas resource in the old sky of extraction, not by old dead zone coal bed gas and is adjacent to mine coal Layer gas resource is planned as a whole to get up, and considers that collaboration is got up extraction.
In fact, often preservation is in coalfield in the form of multilayer coal is separated by a certain distance in coal seam in coalfield, for top Be in the case of the combination geology that old dead zone bottom is thinner seam, excavate exploitation from solid mineral deposit at present (tradition, which is excavated, mines) Often the girdle (0~1.5 meter) larger to underlying seam thickness fluctuations abandon adopting angle, and it is mostly to adopt to abandon the reason for adopting Ore deposit is technically infeasible or technically feasible but it is abandoned from financial cost angle adopted, and this has resulted in most suitable coal A large amount of wastes of (coal bed gas) resource.
For this in view of the above-mentioned problems, the present invention proposes that one kind collapses top from the angle of collaboration extraction, comprehensive exploitation Fall method to exploit to form the method that the extraction simultaneously of old dead zone coal bed gas and bottom girdle coal bed gas goes out.
The content of the invention
Ample resources wasting phenomenon caused by adopting is abandoned for above-mentioned coal (coal bed gas) resource, the present invention proposes that one kind can Cooperate with the coal bed gas pumping method of the old dead zone coal bed gas and can recovery bottom girdle coal bed gas resource in extraction top.
To achieve the above object, technical scheme provided by the invention is：
The invention provides a kind of method for cooperateing with extraction to be caving the old dead zone of formula and lower coal seam coal bed gas, including following step Suddenly：
1) geology digging data is had according to coal mine excavation situation, coal seam block diagram and surface-underground contrast plan etc., simultaneously On-site land survey is carried out to the old dead zone excavated with physical prospecting means, clearly obtains the old dead zone parameter excavated on top (including scope, cavity, coal column distribution situation etc. is excavated in old dead zone), the distance between underlying seam and the old dead zone in top D；
2) the plate destructing depth d as caused by superjacent is caving formula old dead zone excavation is obtained；
3) by ground, middle rock stratum between the old dead zone bottom plate in portion and underlying seam top plate is constructed water upwardly if D≤d Horizontal well, the carbon dioxide 30~60 minutes that valve II is pressed into 1~2MPa from air injection pipe into horizontal well is opened, to horizontal well Cleaned；If during D ﹥ d, by the ground old dead zone plate destructing depth construction level well in portion upwardly, valve II is opened by noting Tracheae is pressed into 1~2MPa carbon dioxide 30~60 minutes into horizontal well, and horizontal well is cleaned；
Horizontal well by underground earthward extended spot be divided into horizontal well horizontal segment, inclination section, horizontal well vertical section and Horizontal well ground surface end, wherein horizontal well ground surface end pass through three reduction of fractions to a common denominators, two branch roads：Drainage tube I and air injection pipe, wherein on drainage tube I Provided with valve I, air injection pipe is provided with valve II, and carrying out sealing to horizontal well vertical section end near the ground forms seal section I, and ground is set There is sealing device I；
4) open valve I and first time coal bed gas extraction is carried out to horizontal well by drainage tube I, record coal in the now unit interval Layer gas extraction amount is Q1；
5) when in the unit interval coal bed gas extraction amount drop to Q120%~40% when, close valve I, stop taking out 12~36 Hour, valve I is again turned on afterwards, while is reduced extraction pressure and continued coal bed gas extraction；When coal bed gas in the unit interval Extraction amount drops to Q again120%~40% when, be again switched off valve I, stop taking out 12~36 hours, be again turned on valve afterwards Door I, extraction pressure is reduced again and carries out coal bed gas extraction；The above-mentioned process for stopping taking out-being depressured extraction is circulated, until extraction pressure drop As little as 80~100kpa is forced down than air；
6) when in the unit interval coal bed gas extraction amount drop to Q1Less than 20% when, close valve I, open valve II by Air injection pipe injects 5~20MPa CO into horizontal well2Gas 8~36 hours, valve II on ground is closed afterwards, wait for 12 quietly~ 48 hours, valve I was again turned on afterwards and carries out coal bed gas extraction；
7) when in the unit interval coal bed gas extraction amount drop to Q again1Less than 20% when, dismantle wellhead tee joint and sealing Device I, staged fracturing equipment is transferred by well head, to the interlayer rock stratum between horizontal well horizontal segment and underlying seam and lower coal Layer implements directional fracturing；
8) horizontal well vertical section is subjected to vertical extension, until extending at 5~20 meters of scopes of underlying seam bottom plate；
9) related mining equipment is installed by horizontal well vertical section, mining equipment is sequentially provided with by underground to above ground portion takes out Oil pump, oil pick-up tube, oil pick-up tube is interior to be provided with sucker rod, and the oil pumper that ground is set drives oil well pump to hang down horizontal well by sucker rod Water in straight section carries out mining；Horizontal well vertical section ground surface end is divided into three branch roads by four-way：Drainpipe, drainage tube II, beam Pipe, drainpipe connection underground oil pick-up tube, ground surface end are provided with valve IV, and the ground surface end of drainage tube II is connected with valve III, beam pipe ground End is connected with valve V, and the underground part of beam pipe is extended in horizontal well horizontal segment, and is in horizontal well horizontal segment Mesh section, sealing is carried out to horizontal well vertical section end near the ground and forms seal section II, ground is provided with sealing device II；
Valve III and valve IV are opened, drives oil well pump to enter the water in horizontal well vertical section by sucker rod by oil pumper Row extraction, while coal bed gas extraction is carried out by drainage tube II, record in mining coal bed gas maximum extraction amount Q in the unit interval2；
10) when in the unit interval coal bed gas extraction amount drop to Q2Less than 20% when, close valve III, valve IV, beat The supercritical CO that the implantation temperature into horizontal well is 32~50 DEG C from beam pipe, pressure is 8~20MPa of valve opening door V224~72 Hour, valve IV is closed, is waited for quietly 12~48 hours；
11) valve III, valve IV are again turned on, carries out drainage and step-down and coal bed gas extraction again by mining equipment；
12) when in the unit interval coal bed gas extraction amount drop to Q2Less than 10% when, stop coal bed gas extraction.
The method that above-mentioned collaboration extraction top is caving the old dead zone of formula and lower coal seam coal bed gas, the old dead zone bottom plate in top The determination of formation damage depth, it is necessary to field measurement, protective coat extracted bottom plate release depth formula, based on moulding theory Floor strata maximal destruction depth formula and laboratory values simulation, the mode of analog simulation or five kinds of methods mutually tie The minimum value for determine, determining to take the above method to obtain during collapse dept is closed as reference value.
The method that above-mentioned collaboration extraction top is caving the old dead zone of formula and lower coal seam coal bed gas, the horizontal well vertical section from Passed through in the coal column of old dead zone border, the horizontal range with border coal column end is 10~60 meters, and horizontal well horizontal segment vertical depth is the bottom of by Interfloor distance between the old dead zone of plate collapse dept and top and underlying seam is determined that horizontal well inclination section kickoff point (KOP) is chosen Then determined by fixed horizontal segment, vertical section layer position and live drilling technology.
The method that above-mentioned collaboration extraction is caving the old dead zone of formula and lower coal seam coal bed gas, the orientation staged fracturing is sleeve pipe One kind in Limited entry fracturing, multiple-string packer staged fracturing or orientation water-jet staged fracturing technology.
Using above-mentioned technical proposal, the beneficial effect that the present invention obtains is：
The invention remains old dead zone big from the angle of coal (coal bed gas) resource coordinating exploitation (extraction) Measure coal bed gas resource and the coal bed gas resource for closing on girdle adopted is abandoned using conventional mining method and take into account, it is proposed that one The innovative approach of kind collaboration extraction coal bed gas.This method can effectively solve original to use the old dead zone of ground vertical drilling extraction merely When, extraction drilling well and the old effective contact area of dead zone reservoir are small, extraction is limited in scope problem；This method avoid ground simultaneously Drilling failure rate caused by above wellbore construction to old dead zone fissure zone is high, the problem that one-tenth porosity is low, difficulty of construction is big；In extraction The coal bed gas resource of girdle will be closed on while old dead zone coal bed gas in the lump in extraction, solves to abandon and adopts dull coal bed gas money The recovery in source, accomplish that a well uses, greatly saved cost；Horizontal well is located at more than underlying seam simultaneously, avoids brill When well is directly beaten to coal seam, the hoistway cave-in accident and hoistway blocking accident that occur because coal seam is excessively loose.
Brief description of the drawings：
Fig. 1 is the structural representation of preliminary stage construction level well extraction process of the present invention.
Fig. 2 is the structural representation that later stage of the present invention sets up extraction process after mining equipment.
1, drainage tube I, 2, valve I in figure, 3, valve II, 4, air injection pipe, 5, horizontal well vertical section, 6, inclination section, 7, point Section fracturing fracture, 8, staged fracturing spacer, 9, horizontal well horizontal segment, 10, top be caving the old dead zone of formula, 11, staged fracturing section, 12nd, coal seam floor failure scope, 13, underlying seam, 14, border coal column, 15, horizontal well, 16, seal section I, 17 sealing devices I, 18th, drainage tube II, 19, valve III, 20, drainpipe, 21, valve IV, 22, beam pipe, 23, valve V, 24, oil pumper, 25, four It is logical, 26, sealing device II, 27, seal section II, 28, oil pick-up tube, 29, sucker rod, 30, oil well pump, 31, threeway.
Embodiment
The present invention is further illustrated below by embodiment, but is not limited to following examples.
Embodiment：
Following examples are intended to schematically illustrate the present invention and explain, not delimit the scope of the invention.
In order to which technical goal, feature and the effect of the present invention have clearer explanation, one kind collaboration is taken out in conjunction with accompanying drawing The method for adopting the old dead zone of the formula of being caving and lower coal seam coal bed gas is described in detail.
Below by taking Jin Mei groups Yue Cheng ore deposit working faces as an example, illustrate the inventive method：Yue Cheng ore deposits are seated Qinshui coalfield, The coalfield is one of abundant important coalfield of China's coal bed gas resource, and minable coal seam is the 3 of Shanxi group in field with "nine squares" in the range of coalfield Number coal seam and No. 9, No. 15 coal seams of Taiyuan Forma-tion.Due to reasons such as the backwardnesss of history and recovery method, main mining coal seam 3 in coalfield Number coal recovery ratio is low, is retained in a large amount of coals in underground, and old dead zone Coal bed gas project is quite abundant.It is with 3 coal seam floor average headways 46 meters No. 9 coals of girdle, its average coal is thick 1 meter, and the coal seam is not yet exploited.If the girdle is opened with the well work in traditional mining mode Adopt then with high costs, it is little to adopt value, but this part resource is hesitated to discard.For satisfactorily resolve top be caving the old dead zone of formula with And the collaboration exploitation of lower coal seam coal bed gas resource, inventive method provided by the invention are specially：
To solve the collaboration of coal (coal bed gas) resource exploitation, the specific method that the invention provides is：
1st, geology digging data is had according to coal mine excavation situation, coal seam block diagram and surface-underground contrast plan etc. and combined The means such as three-dimensional laser scanner, transient electromagnetic method determine that underground top is caving the old dead zone of formula (10) parameter and underlying seam (13) it is caving the distance between the old dead zone of formula (10) D=47 rice with top；The old dead zone parameter includes the scope in post exploiting field, number Mesh and coal column number, size, distribution general location；
2nd, the plate destructing depth d as caused by superjacent is caving formula old dead zone excavation is obtained：On plate destructing depth And the determination of width, need herein with field measurement, protective coat extracted bottom plate release depth formula, based on moulding theory Floor strata maximal destruction depth formula and laboratory values simulation, the mode of analog simulation or five kinds of methods mutually tie The minimum value for determine, determining to take the above method to obtain during collapse dept is closed as reference value；Present example employs protection Layer exploits correlation theory and based on moulding theoretical floor strata maximal destruction depth formula theory：
Obtained according to above-mentioned geology and physical prospecting means：According to geological condition of coal mine and exploitation situation Yue Cheng collieries work It is as follows to make face parameter：The average coal of No. 3 coal seams (protective layer) is thick 6.19 meters, and buried depth 400m seam inclinations are average 3 degree, the working face 3 Average 4 meters of the working thickness of coal (protective layer), working face tendency face grow 125 meters, and across pitch working face face grows 400 meters, and the coal seam is adopted For coal method using longwall is moved towards, roof controlling method is whole caving methods.
A. it is theoretical by protective coat extracted, according to《Prevent and treat coal and gas prominent regulation》Determine plate destructing depth h0:
Protected lower limits can be calculated relative to protection according to bottom release angle (taking 60 degree) and interlamellar spacing (47 meters) Wrong distance is in layer working face：L1=H*ctg60=26m, L2=H*ctg60=26m；
Wherein L1The width that can not be protected relative to protection working face open-off cut side for protected seam；
L2To stop adopting the width that line side can not protect relative to protection working face for protected seam；
Interlayer maximum effective protection aquiclude spacing after No. 3 seam minings：SOn=S'Onβ1β2
According to《Prevent and treat coal and gas prominent regulation》Tabling look-up, it is theoretical effectively maximum vertical away from S' to obtain up-protective layer exploitationOn= 66m, protective layer adopt rear 4m, take β1=1, β2=1, so maximum effective protection aquiclude interval SOnIt is herein, maximum effectively to protect for 66 meters Sheath spacing is based on the theoretical plate destructing depth h of protective coat extracted0, i.e. h0=SOn=66m.
B. by moulding theory analysis floor rock maximal destruction depth h1For：
In above formula, xaSection length is surrendered for coal seam,For the internal friction angle of floor rock；
Herein, coal seam surrender section length xaDetermination can by field measurement or according to A.H.Wilson propose yield limit Formula, coal seam and influence of the roof and floor lithologic to coal seam floor failure are taken into account, if coal strength is less than roof and floor rock mass strength,：
If coal strength is close to when determining floor rock intensity：
Wherein：
To should operating mode, be by correlation report, No. 3 seam mining m=4m, 30 degree of internal friction angle, bottom plate volume-weighted average 2.5t/m3, buried depth H=400 rice, the average internal friction angle of floor rock takes 45 degree, and coal mass strength is less than roof and floor intensity, therefore K1= 3；F=2.55；
So section length is surrendered in coal seam
Floor rock maximal destruction depth h will be brought into1For：
So based on moulding theory analysis floor rock maximal destruction depth h1=21.56m；
To sum up, determine that plate destructing depth takes h in above-mentioned two method0And h1Minimum value be d=min (h0,h1)=21m,
It should be noted that the determination of plate destructing depth can be combined with field measurement data or laboratory herein Interior analog simulation or numerical simulation result, the minimum value in applied method is taken as collapse dept d during value.
3rd, in present example, D ﹥ d (47m>21m), so portion is caving below the old dead zone of formula (10) bottom plate upwardly by ground Construction level well (15) at 21m, open carbon dioxide of the valve II (3) from air injection pipe (4) to the interior press-in 1MPa of horizontal well (15) Gas 30 minutes, is cleaned to horizontal well；
By underground, earthward extended spot is divided into horizontal well horizontal segment (9), inclination section (6), horizontal well to horizontal well (15) Vertical section (5) and horizontal well ground surface end, wherein horizontal well ground surface end are divided to two branch roads by threeway (31)：Drainage tube I (1) and Air injection pipe (4), wherein drainage tube I (1) are provided with valve I (2), and air injection pipe (4) is provided with valve II (3), vertical to horizontal well Section (5) end near the ground carries out sealing and forms seal section I (16), and ground is provided with sealing device I (17)；
4th, open valve I (2) and first time coal bed gas extraction is carried out to horizontal well (15) by drainage tube I (1), record is now single Coal bed gas extraction amount is Q in the time of position1；
5th, when in the unit interval coal bed gas extraction amount drop to Q126% when, close valve I (2), stop taking out 12 hours, it After be again turned on valve I (2), while reduce extraction pressure and continue coal bed gas extraction；When coal bed gas extraction in the unit interval Amount drops to Q again126% when, be again switched off valve I (2), stop taking out 12 hours, be again turned on valve I (2) afterwards, again Reduce extraction pressure and carry out coal bed gas extraction；The above-mentioned process for stopping taking out-being depressured extraction is circulated, until extraction pressure is reduced to than big The low 80kpa of air pressure；
6th, when in the unit interval coal bed gas extraction amount drop to Q1Less than 20% when, close valve I (2), open valve CO of II (3) from air injection pipe (4) to the interior injection 10MPa of horizontal well (15)2Gas 36 hours, valve II on ground is closed afterwards (3), wait for quietly 48 hours, be again turned on valve I (2) afterwards and carry out coal bed gas extraction；
7th, when in the unit interval coal bed gas extraction amount drop to Q again1Less than 20% when, dismounting wellhead tee joint (31) and Sealing device I (17), staged fracturing equipment is transferred by well head, to the layer between horizontal well horizontal segment (9) and underlying seam (13) Between rock stratum and underlying seam (13) implement directional fracturing；
8th, horizontal well vertical section (5) is subjected to vertical extension, until extending at 10 meters of scopes of underlying seam (13) bottom plate；
9th, related mining equipment is installed by horizontal well vertical section (5), mining equipment is set successively by underground to above ground portion There are oil well pump (30), oil pick-up tube (28), sucker rod (29) is provided with oil pick-up tube (28), the oil pumper (24) that ground is set is by taking out Beam hanger (29) driving oil well pump (30) carries out mining to the water in horizontal well vertical section (5)；Horizontal well vertical section (5) ground surface end by Four-way (25) is divided into three branch roads：Drainpipe (20), drainage tube II (18), beam pipe (22), drainpipe (20) connection underground are taken out Oil pipe (28), ground surface end are provided with valve IV (21), and drainage tube II (18) ground surface end is connected with valve III (19), beam pipe (22) ground End is connected with valve V (23), and the underground part of beam pipe (22) is extended in horizontal well horizontal segment (9), and is located at horizontal well It is mesh section in horizontal segment (9), carrying out sealing to horizontal well vertical section (5) end near the ground forms seal section II (27), and ground is set There is sealing device II (26)；
Valve III (19) and valve IV (21) are opened, drives oil well pump (30) right by sucker rod (29) by oil pumper (24) Water in horizontal well vertical section (5) carries out extraction, while carries out coal bed gas extraction by drainage tube II (18), records unit in mining Coal bed gas maximum extraction amount Q in time2；
10th, when in the unit interval coal bed gas extraction amount drop to Q2Less than 20% when, close valve III (19), valve IV (21), open valve V (21) from beam pipe (22) to horizontal well (15) interior implantation temperature be 38 DEG C, pressure be that the super of 15MPa faces Boundary CO224 hours, valve IV (21) is closed, is waited for quietly 12 hours；
11st, valve III (19), valve IV (21) are again turned on, drainage and step-down and coal bed gas are carried out by mining equipment again Extraction；
12nd, when in the unit interval coal bed gas extraction amount drop to Q2Less than 10% when, stop coal bed gas extraction.
In the above method, the top is caving the determination of the old dead zone of formula (10) floor strata collapse dept, it is necessary to existing Actual measurement, protective coat extracted bottom plate release depth formula, based on moulding theoretical floor strata maximal destruction depth formula with And laboratory values simulation, the mode of analog simulation or five kinds of methods are combined to determine, determine to take during collapse dept above-mentioned The minimum value that method obtains is as reference value；
In the above method, the horizontal well vertical section (5) passes through from old dead zone border coal column (14), with border coal column (14) horizontal range of end is 40 meters, and horizontal well inclination section (6) kickoff point (KOP) is chosen then by fixed horizontal well horizontal segment (9), horizontal well vertical section (5) layer position and live drilling technology determine.
In the above method, orientation water-jet staged fracturing technology is employed.

Claims (4)

  1. A kind of 1. method for cooperateing with extraction to be caving the old dead zone of formula and lower coal seam coal bed gas, it is characterised in that：Comprise the following steps：
    1）According to the existing geology digging data of coal mine excavation situation, coal seam block diagram and surface-underground contrast plan, while use thing Reason exploration means carries out on-site land survey to the old dead zone excavated, and clearly obtains the old dead zone parameter excavated on top, lower coal Layer includes old dead zone and excavates scope, cavity, coal column distribution situation with the distance between the old dead zone in top D, old dead zone parameter；
    2）Obtain the plate destructing depth d as caused by superjacent is caving formula old dead zone excavation；
    3）By the ground middle rock stratum construction level well between the old dead zone bottom plate in portion and underlying seam top plate upwardly if D≤d, The carbon dioxide 30 ~ 60 minutes that valve II be pressed into 1 ~ 2MPa from air injection pipe into horizontal well is opened, horizontal well is carried out clearly Wash；If during D ﹥ d, by the ground old dead zone plate destructing depth construction level well in portion upwardly, open valve II from air injection pipe to 1 ~ 2MPa of press-in carbon dioxide 30 ~ 60 minutes, are cleaned to horizontal well in horizontal well；
    By underground, earthward extended spot is divided into horizontal well horizontal segment, inclination section, horizontal well vertical section and level to horizontal well Well ground surface end, wherein horizontal well ground surface end pass through three reduction of fractions to a common denominators, two branch roads：Drainage tube I and air injection pipe, wherein drainage tube I are provided with Valve I, air injection pipe are provided with valve II, and sealing is carried out to horizontal well vertical section end near the ground and forms seal section I, ground is provided with close Seal apparatus I；
    4）Open valve I and first time coal bed gas extraction is carried out to horizontal well by drainage tube I, record coal bed gas in the now unit interval Extraction amount is Q1；
    5）When coal bed gas extraction amount drops to Q in the unit interval120% ~ 40% when, close valve I, stop taking out 12 ~ 36 hours, afterwards Valve I is again turned on, while reduces extraction pressure and continues coal bed gas extraction；When coal bed gas extraction amount is again in the unit interval Drop to Q120% ~ 40% when, be again switched off valve I, stop taking out 12 ~ 36 hours, be again turned on valve I afterwards, again reduce take out Adopt pressure and carry out coal bed gas extraction；The above-mentioned process for stopping taking out-being depressured extraction is circulated, until extraction pressure is reduced to and forced down than air 80~100kpa；
    6）When coal bed gas extraction amount drops to Q in the unit interval1Less than 20% when, close valve I, open valve II by air injection pipe 5 ~ 20MPa CO is injected into horizontal well2Gas 8 ~ 36 hours, valve II on ground is closed afterwards, is waited for quietly 12 ~ 48 hours, it After be again turned on valve I carry out coal bed gas extraction；
    7）When coal bed gas extraction amount drops to Q again in the unit interval1Less than 20% when, dismantle wellhead tee joint and sealing device I, Staged fracturing equipment is transferred by well head, the interlayer rock stratum between horizontal well horizontal segment and underlying seam and underlying seam are implemented Directional fracturing；
    8）Horizontal well vertical section is subjected to vertical extension, until extending at 5 ~ 20 meters of scopes of underlying seam bottom plate；
    9）Related mining equipment is installed by horizontal well vertical section, mining equipment is sequentially provided with oil pumping by underground to above ground portion Pump, oil pick-up tube, oil pick-up tube is interior to be provided with sucker rod, and the oil pumper that ground is set drives oil well pump vertical to horizontal well by sucker rod Water in section carries out mining；Horizontal well vertical section ground surface end is divided into three branch roads by four-way：Drainpipe, drainage tube II, beam pipe, Drainpipe connects underground oil pick-up tube, and ground surface end is provided with valve IV, and the ground surface end of drainage tube II is connected with valve III, and beam pipe ground surface end connects There is valve V, the underground part of beam pipe is extended in horizontal well horizontal segment, and is mesh in horizontal well horizontal segment Section, sealing is carried out to horizontal well vertical section end near the ground and forms seal section II, ground is provided with sealing device II；
    Valve III and valve IV are opened, drives oil well pump to take out the water in horizontal well vertical section by sucker rod by oil pumper Adopt, while coal bed gas extraction is carried out by drainage tube II, record in mining coal bed gas maximum extraction amount Q in the unit interval2；
    10）When coal bed gas extraction amount drops to Q in the unit interval2Less than 20% when, close valve III, valve IV, open valve V supercritical CO that implantation temperature is 32 ~ 50 DEG C into horizontal well from beam pipe, pressure is 8 ~ 20MPa2 24 ~ 72 hours, close Valve IV, wait for quietly 12 ~ 48 hours；
    11）Valve III, valve IV are again turned on, carries out drainage and step-down and coal bed gas extraction again by mining equipment；
    12）When coal bed gas extraction amount drops to Q in the unit interval2Less than 10% when, stop coal bed gas extraction.
  2. 2. the method that the collaboration extraction according to claims 1 is caving the old dead zone of formula and lower coal seam coal bed gas, its feature exist In：The determination of the old dead zone plate destructing depth in top is, it is necessary to public with field measurement, protective coat extracted bottom plate release depth Formula, based on moulding theoretical floor strata maximal destruction depth formula and laboratory values simulation, analog simulation it is any Mode that mode or five kinds of methods are combined determines that the minimum value for determining to take aforesaid way to obtain during collapse dept is as ginseng Examine value.
  3. 3. the method that collaboration extraction according to claim 1 is caving the old dead zone of formula and lower coal seam coal bed gas, it is characterised in that： The horizontal well vertical section passes through from the coal column of old dead zone border, and the horizontal range with border coal column end is 10 ~ 60 meters, horizontal Well horizontal segment vertical depth determined by the interfloor distance between the old dead zone of plate destructing depth and top and underlying seam, horizontal well Inclination section kickoff point (KOP) is chosen and determined by fixed horizontal well horizontal segment, horizontal well vertical section layer position and live drilling technology.
  4. 4. the method that collaboration extraction according to claim 1 is caving the old dead zone of formula and lower coal seam coal bed gas, it is characterised in that： The orientation staged fracturing is in sleeve pipe Limited entry fracturing, multiple-string packer staged fracturing or orientation water-jet staged fracturing technology One kind.
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