CN108240209A - A kind of method of coal bed gas well secondary fracturing - Google Patents
A kind of method of coal bed gas well secondary fracturing Download PDFInfo
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- 239000003245 coal Substances 0.000 title claims abstract description 124
- 238000000034 method Methods 0.000 title claims abstract description 40
- 239000012530 fluid Substances 0.000 claims abstract description 162
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 73
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 79
- 239000004576 sand Substances 0.000 claims description 77
- 239000007788 liquid Substances 0.000 claims description 22
- 238000006073 displacement reaction Methods 0.000 claims description 17
- 230000000694 effects Effects 0.000 claims description 9
- 239000006004 Quartz sand Substances 0.000 claims description 6
- 238000005406 washing Methods 0.000 claims description 5
- 239000007864 aqueous solution Substances 0.000 claims description 4
- 238000000465 moulding Methods 0.000 claims description 2
- 238000004519 manufacturing process Methods 0.000 abstract description 12
- 208000010392 Bone Fractures Diseases 0.000 abstract description 9
- 206010017076 Fracture Diseases 0.000 abstract description 9
- 230000009471 action Effects 0.000 abstract description 7
- 230000009466 transformation Effects 0.000 description 6
- 239000000243 solution Substances 0.000 description 5
- 239000004677 Nylon Substances 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 4
- 229920001778 nylon Polymers 0.000 description 4
- 230000000903 blocking effect Effects 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 238000002347 injection Methods 0.000 description 3
- 239000007924 injection Substances 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 2
- 239000004927 clay Substances 0.000 description 2
- 239000002817 coal dust Substances 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 230000013011 mating Effects 0.000 description 2
- 238000005065 mining Methods 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000009530 blood pressure measurement Methods 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
- 238000004080 punching Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 230000000638 stimulation Effects 0.000 description 1
- 239000004575 stone Substances 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
Classifications
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- 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
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Abstract
The invention discloses a kind of methods of coal bed gas well secondary fracturing, belong to coal bed gas well fracturing technique field.This method includes：Fracturing unit truck group is opened, and passes through fracturing unit truck group and note fracturing fluid is pumped into target coal seam gas well, small-scale pressure break is carried out, to dredge primary fracture in reservoir.Into target coal seam gas well, input is less than multiple ball sealers of preforation tunnel number, at the same time, note active water fracturing fluid is pumped into target coal seam gas well using fracturing unit truck group, ball sealer blocks the preforation tunnel of original pressure-break under active water pressure break action of hydraulic force.Continue scale pressure break during pump note fracturing fluid carries out into target coal seam gas well using fracturing unit truck group, new pressure-break is formed in reservoir.Fracturing unit truck group is closed, is left after preforation tunnel falls into shaft bottom after ball sealer, ball sealer is returned and drains into ground, completes secondary fracturing.It effectively solves the problems, such as that coal bed gas well gas production caused by since first fracturing reform range is small is low using this method, improves the production efficiency of coal bed gas.
Description
Technical field
The present invention relates to coal bed gas well fracturing technique field, more particularly to a kind of method of coal bed gas well secondary fracturing.
Background technology
Coal bed gas is mainly housed in coal petrography, and coalbed methane reservoir is transformed by fracturing technique, can improve the exploitation of coal bed gas
Efficiency.At present, mainly coalbed methane reservoir is transformed by hydraulic fracturing technology, so as to occur one or more in reservoir
The pressure-break communicated with coal bed gas well, and then improve the yield of coal bed gas well.Coal bed gas well after hydraulic fracturing, due to
Fracturing reform range is small for the first time, causes part well yield low；During mining due to crack closure, coal dust blocking etc.,
Part well yield is caused to decline.Currently for coal bed gas well effective well stimulation for de-plugging secondary fracturing technique, the work
Skill achievees the purpose that restore well yield by dredging primary fracture.
Patent document CN104251131A provides a kind of coal bed gas well de-plugging secondary fracturing method, including recycling, trying
Pressure, pressure break plus sand, bleed off pressure five steps at pressure measurement drop.The method of the secondary fracturing is specially：(1) with pressure break pump truck by fracturing fluid
Pressure break pump truck is got to by tank truck and returns again to tank truck, checks the working condition of fracturing pump and pipeline.(2) it is then shut off well head lock
Door, builds the pressure to ground high pressure line, stablizes 5 minutes, do not pierce and do not leak, and pressure testing is qualified.(3) with pressure break pump truck to coal bed gas well
Interior pump note fracturing fluid, during the pressure born more than reservoir, reservoir forms pressure-break.(4) the pump note load fluid into coal bed gas well,
To form sand packed fracture.(5) pressure drop in coal bed gas well is surveyed using pressure gauge.(6) and then closing well, open flow.Wherein, fracturing fluid is used
It measures as 600-800m3, fracturing fluid is configured to a concentration of 1% solution by water and expansion-resisting agent KCl, and fracturing pump pump note discharge capacity is 6-
8m3/ min, quartz sand sand amount are 40-60m3, the wherein coarse sand 10m of grain size 0.85-1.15mm320% is accounted for, grain size 0.425-
Sand accounts for 80% in 0.85mm.This method can effectively solve the problem that in coal bed gas well production process due to the closure of fracturing fracture, gas well
The problem of reasons such as blocking of coal dust output object fracture cause yield to decline during output.
Inventor has found that the prior art has at least the following problems：
Although the method for the coal bed gas well secondary fracturing that the prior art provides can reach recovery list by dredging primary fracture
The purpose of well production, but can not solve the problems, such as first fracturing reform range it is small caused by low yield, the production efficiency of coal bed gas well
Raising that cannot be by a relatively large margin.
Invention content
Technical problem to be solved of the embodiment of the present invention is, provide one kind can solve coal seam gas production well due to
Gas production caused by fracturing reform range is small for the first time is low, and the coal bed gas well that can greatly improve the production efficiency of coal bed gas is secondary
The method of pressure break.Specific technical solution is as follows：
An embodiment of the present invention provides a kind of methods of coal bed gas well secondary fracturing, the described method comprises the following steps：
Step a, fracturing unit truck group is opened, and pumps note fracturing fluid into target coal seam gas well by the fracturing unit truck group, is carried out
Small-scale pressure break, to dredge original pressure-break in reservoir.
Step b, into the target coal seam gas well, input is less than multiple ball sealers of preforation tunnel number, at the same time,
Note active water fracturing fluid is pumped into the target coal seam gas well using the fracturing unit truck group, the ball sealer is in the active hydraulic pressure
It splits and the preforation tunnel of original pressure-break is blocked under action of hydraulic force.
Step c, continue pump note fracturing fluid, scale pressure in progress into the target coal seam gas well using the fracturing unit truck group
It splits, new pressure-break is formed in the reservoir.
Step d, close the fracturing unit truck group, left after the preforation tunnel falls into shaft bottom after the ball sealer, will described in
Ball sealer, which returns, drains into ground, completes the secondary fracturing to the target coal seam gas well.
Specifically, preferably, in the step a into the target coal seam gas well pump note fracturing fluid and described to described
Continue pump note fracturing fluid in target coal seam gas well to include：Into the target coal seam gas well sequentially pump note prepad fluid, load fluid,
Displacement fluid；In the step b, the active water fracturing fluid is to be configured to the water-soluble of a concentration of 0.5%-1.5% by clear water and KCl
Liquid.
Specifically, preferably, in the step a, when carrying out the small-scale pressure break, the prepad fluid is 50-
60m3Active water fracturing fluid, the load fluid are 140-150m3Active water fracturing fluid and 10-15m3The mixed liquor of sand grains, the top
It is active water fracturing fluid for liquid, discharge capacity is by 1m3/ min steps progressively increase to 5m3/min。
Specifically, preferably, when carrying out the middle scale pressure break, the prepad fluid is 50-60m3Active water pressure break
Liquid, the load fluid are 180-200m3Active water fracturing fluid and 20-25m3The mixed liquor of sand grains, the displacement fluid are active hydraulic pressure
Liquid is split, discharge capacity is by 1m3/ min steps progressively increase to 6m3/min。
Specifically, preferably, when into the target coal seam gas well, pump notes the load fluid, the sand grains is quartz
Sand, first load fluid of the pump note containing the fine sand that granularity is 40-70 mesh, then pumps note and contains the sand grains that granularity is 20-40 mesh
Load fluid.
Specifically, preferably, when carrying out the small-scale pressure break, the volume of the sand grains accounts for the sand grains totality
Long-pending 60%-70%；When carrying out the middle scale pressure break, the volume of the sand grains accounts for the 75%- of the sand grains total volume
80%.
Specifically, preferably, 1-2 times of a diameter of preforation tunnel diameter of the ball sealer, density 1.1-
1.2g/cm3。
Specifically, preferably, the number of the ball sealer put into the target coal seam gas well can according to
Lower formula obtains：
Wherein, n is the second predetermined amount；Any values of the k between 1.1-1.2；M is the number of the preforation tunnel.
Specifically, preferably, in the step b, the volume of the active water fracturing fluid is 10-12m3, discharge capacity by
1m3/ min progressively increases to 2m3/min。
Specifically, preferably, being left after the preforation tunnel falls into shaft bottom after the ball sealer, carry out successively open flow,
Then the ball sealer is returned and drains into ground by sand washing operation again, complete the secondary fracturing to the target coal seam gas well.
The advantageous effect that technical solution provided in an embodiment of the present invention is brought is：
A kind of method of coal bed gas well secondary fracturing provided in an embodiment of the present invention is noted by being pumped into target coal seam gas well
Fracturing fluid can dredge original pressure-break in reservoir to carry out small-scale pressure break.After original pressure-break is dredged, by target coal
Input is less than multiple ball sealers of preforation tunnel number in layer gas well, and coordinates with the active water fracturing fluid of fracturing unit truck group pump note,
The preforation tunnel of original pressure-break can be blocked, convenient for continuing the fracturing fluid of pump note pressure break at the preforation tunnel not blocked
Go out new pressure-break, to increase the transformation area of reservoir, the production efficiency of coal bed gas can be greatly improved.
Description of the drawings
To describe the technical solutions in the embodiments of the present invention more clearly, make required in being described below to embodiment
Attached drawing is briefly described, it should be apparent that, the accompanying drawings in the following description is only some embodiments of the present invention, for
For those of ordinary skill in the art, without creative efforts, other are can also be obtained according to these attached drawings
Attached drawing.
Fig. 1 is the method flow diagram of coal bed gas well secondary fracturing provided in an embodiment of the present invention；
Fig. 2-1 be target coal seam gas well provided in an embodiment of the present invention without secondary fracturing before, the structure diagram of reservoir；
Fig. 2-2 is schematic diagram when ball sealer provided in an embodiment of the present invention blocks the preforation tunnel in reservoir；
When Fig. 2-3 is target coal seam gas well secondary fracturing provided in an embodiment of the present invention, new pressure-break is generated in reservoir
Schematic diagram.
Wherein, reference numeral represents respectively：
1 target coal seam gas well,
2 reservoirs,
3 original pressure-breaks,
4 ball sealers,
5 preforation tunnels,
6 new pressure-breaks.
Specific embodiment
Unless otherwise defined, all technical terms used in the embodiment of the present invention are respectively provided with usual with those skilled in the art
The identical meaning understood.To make the object, technical solutions and advantages of the present invention clearer, below in conjunction with attached drawing to this hair
Bright embodiment is described in further detail.
An embodiment of the present invention provides a kind of method of coal bed gas well secondary fracturing, as shown in Figure 1, this method include with
Lower step：
Step 101 opens fracturing unit truck group, and passes through fracturing unit truck group and note fracturing fluid is pumped into target coal seam gas well, carries out small
Scale pressure break, to dredge original pressure-break in reservoir.
Step 102, into target coal seam gas well, input is less than multiple ball sealers of preforation tunnel number, at the same time, profit
Note active water fracturing fluid is pumped into target coal seam gas well with fracturing unit truck group, ball sealer is under active water pressure break action of hydraulic force to original
The preforation tunnel for having pressure-break is blocked.
Step 103 continues into target coal seam gas well pump note fracturing fluid using fracturing unit truck group, scale pressure break in progress,
New pressure-break is formed in reservoir.
Step 104 closes fracturing unit truck group, is left after preforation tunnel falls into shaft bottom after ball sealer, ball sealer is returned and drains into ground
The secondary fracturing to target coal seam gas well is completed in face.
A kind of method of coal bed gas well secondary fracturing provided in an embodiment of the present invention is given below and is described：
As shown in attached drawing 2-1, attached drawing 2-2 and attached drawing 2-3, target coal seam gas well 1 is not when carrying out secondary fracturing, storage
There are original pressure-break 3 and preforation tunnels 5, partial completion eyelet 5 in layer 2 to be located in original pressure-break 3, partial completion hole
Original pressure-break 3 is not present at eye 5.Before secondary fracturing is carried out, first turn on fracturing unit truck and assemble the corresponding fracturing fluid of system, and to
Pump note fracturing fluid in target coal seam gas well 1, to carry out small-scale pressure break, to dredge original pressure-break 3 in reservoir 2, after being convenient for
Phase ball sealer 4 blocks the preforation tunnel 5 in original pressure-break 3.Then multiple ball sealers 4 are put into target coal seam gas well 1, are thrown
The quantity for entering ball sealer 4 is less than the number of preforation tunnel 5 in target coal seam gas well 1, at the same time, using fracturing unit truck group to target
Pump note active water fracturing fluid in coal bed gas well 1, ball sealer 4 is carried by active water fracturing fluid to well, at original pressure-break 3
Stress it is low, ball sealer 4 is migrated under the action of active water fracturing fluid to the preforation tunnel 5 of original pressure-break 3, and in activity
Hydraulic pressure splits closure preforation tunnel 5 under action of hydraulic force.Further injection pressure is pumped into target coal seam gas well 1 using fracturing unit truck group to split
Scale pressure break during liquid carries out, in the process, fracturing fluid gives ball sealer 4 pressure, and ball sealer 4 continues to block preforation tunnel 5, together
When fracturing fluid pressure break is carried out at the preforation tunnel 5 not blocked, to form new pressure-break 6.Fracturing unit truck group is then shut off, no longer
Have in pressure break liquid pump injection target coal seam gas well 1, ball sealer 4 falls into shaft bottom since gravity leaves preforation tunnel 5 at this time, so
Ball sealer 4 is returned by open flow, sand washing operation afterwards and drains into ground, completes the secondary fracturing to target coal seam gas well 1.It is also, right
For target coal seam gas well 1, the number of contained preforation tunnel 5 is once presses target coal seam gas well 1 on reservoir 2
By perforating methods (such as jet perforating) to reservoir perforation before splitting, with the number of the original preforation tunnel of acquisition, number note
It records in early period gasser transformation process in obtained data, is obtained by consulting.
It should be noted that as shown in attached drawing 2-1, preforation tunnel 5 is located in original pressure-break 3, exists in and does not press
On the reservoir 2 in crack, secondary fracturing can be to the Perforation that is not blocked at the preforation tunnel 5 of no pressure-break or by ball sealer 4
Pressure break is carried out at eye 5." target coal seam gas well 1 " is after first time pressure break, and the transformation area of reservoir 2 is small, and uses one section
Production efficiency is lower after time, needs that the coal bed gas well of its reservoir 2 is further transformed.It is understood that " small-scale pressure break "
To pump the fracturing fluid of note into target coal seam gas well less than " middle scale pressure break ", " small-scale pressure break " is mainly to dredge reservoir Central Plains
Have based on pressure-break, " middle scale pressure break " is mainly made to be formed in reservoir with pressure break based on new pressure-break.
Based on above-mentioned it is found that a kind of method of coal bed gas well secondary fracturing provided in an embodiment of the present invention, by target
Pump note fracturing fluid can dredge original pressure-break in reservoir to carry out small-scale pressure break in coal bed gas well.Dredging original pressure-break
Afterwards, by putting into multiple ball sealers less than preforation tunnel number, and the work noted with fracturing unit truck group pump into target coal seam gas well
Property the cooperation of water fracturing fluid, the preforation tunnel of original pressure-break can be blocked, the fracturing fluid convenient for continuing pump note is not blocking
Preforation tunnel at pressure break go out new pressure-break, to increase the transformation area of reservoir, can greatly improve coal bed gas exploitation effect
Rate.
Specifically, in embodiments of the present invention, fracturing unit truck group includes pressure break pump truck, fracturing blender truck, tank truck, pressure break header
Vehicle, measuring truck, under the control action of measuring truck, fracturing fluid is pressurizeed by pressure break pump truck, and passes through pressure break header vehicle to target
Pump note fracturing fluid in coal bed gas well, to carry out pressure break.Wherein, fracturing fluid can be forced into more than coal bed gas well reservoir by pressure break pump truck
Pressure, in order to which pressure break occurs for reservoir, proppant and liquid can be sufficiently mixed by fracturing blender truck, and tank truck can be provided for pump truck to be filled
The liquid of foot.The concrete structure and operation principle of fracturing unit truck group are well known to those skilled in the art, and this will not be detailed here.
Specifically, in a step 101, it before the pump note fracturing fluid into target coal seam gas well, needs target coal seam gas first
Well stops well, and checks whether fracturing unit truck group being capable of normal operation.Then injection pressure is pumped into target coal seam gas well using fracturing unit truck group
Liquid is split, carries out small-scale pressure break, it is main to dredge original pressure-break in reservoir, it is also possible to form a small number of new pressure-breaks or non-shape
The pressure-break of Cheng Xin.
Wherein, into target coal seam gas well, pump note fracturing fluid includes sequentially pumping note prepad fluid into target coal seam gas well, take
Sand liquid, displacement fluid.Wherein, convenient for seam, cooling, load fluid proppant easy to carry enters formation back-up sand in crack and splits prepad fluid
Seam, so that pressure-break is not closed, displacement fluid can replace load fluid to precalculated position, so that the proppant in load fluid is preferably
Support fracturing stitches.When carrying out small-scale pressure break, prepad fluid 50-60m3Active water fracturing fluid, load fluid 140-150m3It is living
Property water fracturing fluid and 10-15m3The mixed liquor of sand grains, displacement fluid are active water fracturing fluid, and discharge capacity is by 1m3/ min steps gradually increase
It is added to 5m3/ min, such as prepad fluid can be 50m3、52m3、54m3、56m3、58m3、60m3Deng active water fracturing fluid, take sand
Liquid can be 140m3Active water fracturing fluid and 10m3Mixed liquor, the 144m of sand grains3Active water fracturing fluid and 12m3The mixing of sand grains
Liquid, 148m3Active water fracturing fluid and 14m3Mixed liquor, the 150m of sand grains3Active water fracturing fluid and 15m3Mixed liquor of sand grains etc.,
Using the displacement fluid of the prepad fluid of above-mentioned volume, load fluid and above-mentioned change discharge capacity, it can play and excellently dredge original pressure-break
Effect.Wherein, the discharge capacity of displacement fluid can be understood as the increase of discharge capacity constant gradient using " step " discharge capacity, such as discharge capacity can be with
It is followed successively by 1m3/min、2m3/min、3m3/min、4m3/min、5m3/ min, the pump fluence of displacement fluid can according to hole volume and
Discharge capacity is noted to pump, and those skilled in the art can rule of thumb determine that this will not be detailed here.Wherein, to target coal seam gas
In well during pump note load fluid, first pump note is containing load fluid of the granularity for the fine sand of 40-70 mesh, such as the granularity of fine sand can be with
For 40 mesh, 50 mesh, 60 mesh, 70 mesh etc., then pump note and contain load fluid of the granularity for the sand grains of 20-40 mesh, such as sand grains
Granularity can be 20 mesh, 25 mesh, 30 mesh, 35 mesh, 40 mesh etc., and the volume of sand grains accounts for the 60%- of sand grains total volume
70%, such as can be 60%, 62%, 64%, 66%, 68%, 70% etc..The granularity and ratio of load fluid sand grains is arranged such
Example, can make fine sand and sand grains mating reaction, support original pressure-break, efficiently to dredge original pressure-break, and first pump
The load fluid containing fine sand is noted, to be supported to distant place fine cracks in reservoir, then pump note takes sand containing sand grains
Liquid is to be supported large fracture more nearby, so that original pressure-break is dredged.Wherein, sand grains is quartz sand, quartz sand
It is cheap, easily obtain.Active water fracturing fluid is the aqueous solution that a concentration of 0.5%-1.5% is configured to by clear water and KCl, dense
Degree represents the mass concentration of KCl, can prevent clay from expanding using the active water fracturing fluid, small to the nocuity of coal seam reservoirs,
Ensure the stability of coal seam reservoirs, be conducive to the exploitation of coal bed gas.
Specifically, in a step 102, multiple ball sealers less than preforation tunnel number are put into target coal seam gas well,
At the same time, note active water fracturing fluid is pumped into target coal seam gas well using fracturing unit truck group, wherein, the volume of active water fracturing fluid
For 10-12m3, discharge capacity is by 1m3/ min progressively increases to 2m3/ min is reached in well in order to carry ball sealer, due to original pressure break
Stress at seam is low, and ball sealer is migrated under the action of active water pressure break hydraulic coupling to progress at the preforation tunnel of original pressure-break
It blocks.
Wherein, 1-2 times of a diameter of preforation tunnel diameter of ball sealer, can block preforation tunnel, density is
1.1-1.2g/cm3, the ball sealer under this kind of density can mix, and can be in active water fracturing fluid with active water fracturing fluid
Pressure effect is lower to block preforation tunnel, the preforation tunnel of especially original pressure-break；In addition, this kind of ball sealer be conducive to through water or
The carrying of other liquid, which is returned, drains into ground.For example, such ball sealer can be nylon ball, ball or steel-reinforced rubber ball,
Cheap, the easily acquisition of these types of ball sealer, recyclable reuse.
Specifically, ball sealer can be put into well by being arranged on the ball injector of target coal seam gas well mouth, to target coal
The number of ball sealer put into layer gas well can be obtained according to the following formula：
Wherein, n is the second predetermined amount；Any values of the k between 1.1-1.2；M is the number of preforation tunnel.
The number of the ball sealer of input is arranged such, can block at large fracture and the part small crack in original pressure-break
Preforation tunnel, does not block or a small number of block in reservoir does not have the preforation tunnel of original pressure-break, in order to be carried out in step 103
Middle scale pressure break.
Specifically, in step 103, continue to advise during pump note fracturing fluid carries out into target coal seam gas well using fracturing unit truck group
Molding is split, and fracturing fluid inside the preforation tunnel pressure break to reservoir that is not blocked by forming new pressure-break, i.e., new pressure break
Seam.Wherein, continue into target coal seam gas well pump note fracturing fluid include sequentially pumped into target coal seam gas well note prepad fluid,
Load fluid, displacement fluid.During underway scale pressure break, prepad fluid 50-60m3Active water fracturing fluid, load fluid 180-200m3
Active water fracturing fluid and 20-25m3The mixed liquor of sand grains, displacement fluid are active water fracturing fluid, and discharge capacity is by 1m3/ min steps are gradual
Increase to 6m3/ min, such as prepad fluid can be 50m3、51m3、53m3、55m3、57m3、59m3、60m3Deng active water pressure break
Liquid, load fluid can be 180m3Active water fracturing fluid and 20m3Mixed liquor, the 185m of sand grains3Water active water fracturing fluid and 21m3Sand
Mixed liquor, the 190m of grain3Active water fracturing fluid and 23m3Mixed liquor, the 195m of sand grains3Active water fracturing fluid and 24m3Sand grains mixes
Close liquid, 200m3Active water fracturing fluid and 25m3Mixed liquor of sand grains etc., using the prepad fluid of above-mentioned volume, load fluid and above-mentioned
The displacement fluid of discharge capacity can form new pressure-break, to increase the transformation area of the target coal seam gas well reservoir.Wherein, it replaces
The discharge capacity of liquid can be understood as the increase of discharge capacity constant gradient using " step " discharge capacity, such as discharge capacity can be followed successively by 1m3/min、
2m3/min、3m3/min、4m3/min、5m3/ min, the pump fluence of displacement fluid can pump note according to hole volume and discharge capacity, this
Field technology personnel can rule of thumb determine that this will not be detailed here.Wherein, in the pump note load fluid into target coal seam gas well
When, first pump note contains the sand grains that granularity is 20-40 mesh containing load fluid of the granularity for the fine sand of 40-70 mesh, then pump note
Load fluid, and the volume of sand grains accounts for the 75%-80% of sand grains total volume, for example, can be 75%, 76%, 77%,
78%th, 79%, 80% etc., the granularity and ratio of load fluid sand grains is arranged such, fine sand and sand grains mating reaction can be made,
New pressure-break is supported, good back-up sand water conservancy diversion crack can be formed, to increase the target coal seam gas well reservoir reconstruction area,
In, first load fluid of the pump note containing fine sand, is supported distant place fine cracks in reservoir convenient for fine sand, and then pump note contains
There is the load fluid of sand grains, to be supported to large fracture more nearby, to support new pressure-break.Wherein, sand grains is stone
Sand, cheap, the easily acquisition of quartz sand.Active water fracturing fluid is to be configured to a concentration of 0.5%- by clear water and KCl
1.5% aqueous solution, concentration represent the mass concentration of KCl, can prevent clay from expanding using the active water fracturing fluid, to coal
The nocuity of reservoir is small, ensures the stability of coal seam reservoirs, is conducive to the exploitation of coal bed gas.
Specifically, at step 104, fracturing unit truck group is closed, stops pump note fracturing fluid, ball sealer into target coal seam gas well
Be not subjected to pump in step 102 the active water fracturing fluid of note pressure effect or step 103 in pump note fracturing fluid pressure
Effect, therefore ball sealer falls to shaft bottom from preforation tunnel, leaves after preforation tunnel falls into shaft bottom after ball sealer, is put successively
Spray, sand washing operation, then ball sealer is returned and drains into ground, complete the secondary fracturing to target coal seam gas well again.Specific open flow, punching
Sand and the row of returning are accomplished by the following way：
By installing discharge nozzle on the relief line of target coal seam gas well mouth, and valve is opened, make target coal seam gas
Fracturing fluid and the mixed liquor open flow of active water fracturing fluid and other substances to ground in well.Then fracturing unit truck group is utilized to mesh
It marks pump in coal bed gas well and notes suitable water, and the sand broken up is carried to ground by the liquid returned in high speed, at the same time,
Ball sealer is also carried into ground.
To the present invention be further described through by specific embodiment below.
In specific examples below, condition person is not specified in involved operation, according to normal condition or manufacturer
It is recommended that condition carry out.It is raw materials used be not specified production firm and specification person be can be with conventional products that are commercially available.
Embodiment 1
The present embodiment 1 evaluates the effect of increasing production of the method for coal bed gas well secondary fracturing provided by the invention.With X wells
For target coal seam gas well, the highest daily output tolerance of the well is 600m3, the daily output of the neighbouring coal bed gas well of surrounding is in 1000m3
More than, but the average value of the daily output tolerance of the well in the recent period is in 144m3Left and right, therefore it is that the daily output tolerance of the target coal seam gas well is low
Pressure break is small to the transformation area of reservoir, and the original pressure-break in part blocks, therefore is selected as target coal seam gas well.It is such as attached
Shown in Fig. 2-1, there are original pressure-break 3, preforation tunnel 5, partial completion eyelets in the reservoir 2 in target coal seam gas well 1 (X wells)
5 are located in original pressure-break 3, and original pressure-break 3 is not present at partial completion eyelet 5.Then using following methods to the target
Coal bed gas well 1 carries out secondary fracturing：
First, fracturing unit truck group is opened, and passes through fracturing unit truck group and note 60m is sequentially pumped into X wells3Active water fracturing fluid is (preposition
Liquid), 150m3Active water fracturing fluid and fine sand 5m3And sand grains 10m3Mixed liquor (load fluid), 9.3m3Active water pressure break
(displacement fluid, discharge capacity is by 1m for liquid3/ min progressively increases to 5m3/ min) small-scale pressure break is carried out, to dredge original pressure break in reservoir 2
Seam 3, wherein, load fluid of the note containing fine sand is first pumped for load fluid, then pump load fluid of the note containing sand grains.Then it uses
Ball injector puts into 45 nylon balls 4 to the X wells, and concurrent fracturing vehicle group pumps note 10m into X wells3Active water fracturing fluid, discharge capacity by
1m3/ min progressively increases to 2m3/ min makes nylon ball 4 block the preforation tunnel 5 of original pressure-break 3, referring to attached drawing 2-2.Then
Using fracturing unit truck group, into X wells, sequentially pump notes 60m3Active water fracturing fluid (prepad fluid), 200m3Active water fracturing fluid and fine sand
5m3And sand grains 15m3Mixed liquor (load fluid), 9.3m3(displacement fluid, discharge capacity is by 1m for active water fracturing fluid3/ min gradually increases
It is added to 6m3/ min) carry out in scale pressure break, new pressure-break 6 is formed, referring to attached drawing 2-3.Fracturing unit truck group is finally closed, treats Buddhist nun
After imperial ball 4 falls into shaft bottom, nylon ball 4 is returned and drains into ground by open flow, sand washing, completes secondary fracturing.Wherein, active water pressure break
Liquid is configured to a concentration of 1% aqueous solution for clear water and KCl.
Then rerun X wells, after 1 year mining phase, the daily output tolerance of the X wells is 1806m3.As it can be seen that this hair
The reservoir area of coal bed gas well can be significantly transformed in the method for the coal bed gas well secondary fracturing of bright offer, can greatly improve coal seam
The gas producing efficiency of gas well.
The foregoing is merely presently preferred embodiments of the present invention, the protection domain being not intended to limit the invention, all in this hair
Within bright spirit and principle, any modification, equivalent replacement, improvement and so on should be included in protection scope of the present invention
Within.
Claims (10)
- A kind of 1. method of coal bed gas well secondary fracturing, which is characterized in that the described method comprises the following steps：Step a, fracturing unit truck group is opened, and pumps note fracturing fluid into target coal seam gas well by the fracturing unit truck group, carries out small rule Molding is split, to dredge original pressure-break in reservoir；Step b, into the target coal seam gas well, at the same time input, is utilized less than multiple ball sealers of preforation tunnel number The fracturing unit truck group pumps note active water fracturing fluid into the target coal seam gas well, and the ball sealer is in the active water fracturing fluid The preforation tunnel of original pressure-break is blocked under pressure effect；Step c, continue into the target coal seam gas well pump note fracturing fluid using the fracturing unit truck group, scale pressure break in progress, New pressure-break is formed in the reservoir；Step d, the fracturing unit truck group is closed, is left after the preforation tunnel falls into shaft bottom after the ball sealer, by the closure Ball, which returns, drains into ground, completes the secondary fracturing to the target coal seam gas well.
- 2. according to the method described in claim 1, it is characterized in that, note is pumped in the step a into the target coal seam gas well Continue pump note fracturing fluid in fracturing fluid and the step c into the target coal seam gas well to include：To the target coal seam gas Sequentially pump notes prepad fluid, load fluid, displacement fluid in well；In the step b, the active water fracturing fluid is the aqueous solution that a concentration of 0.5%-1.5% is configured to by clear water and KCl.
- 3. according to the method described in claim 2, it is characterized in that, in the step a, when carrying out the small-scale pressure break, The prepad fluid is 50-60m3Active water fracturing fluid, the load fluid are 140-150m3Active water fracturing fluid and 10-15m3Sand grains Mixed liquor, the displacement fluid be active water fracturing fluid, discharge capacity is by 1m3/ min steps progressively increase to 5m3/min。
- 4. according to the method described in claim 2, it is characterized in that, when carrying out the middle scale pressure break, the prepad fluid is 50-60m3Active water fracturing fluid, the load fluid are 180-200m3Active water fracturing fluid and 20-25m3The mixed liquor of sand grains, institute Displacement fluid is stated as active water fracturing fluid, discharge capacity is by 1m3/ min steps progressively increase to 6m3/min。
- 5. method according to claim 3 or 4, which is characterized in that taken described in the pump note into the target coal seam gas well During sand liquid, the sand grains is quartz sand, and first pump note contains containing load fluid of the granularity for the fine sand of 40-70 mesh, then pump note Load fluid of the granularity for the sand grains of 20-40 mesh.
- 6. according to the method described in claim 5, it is characterized in that, when carrying out the small-scale pressure break, the sand grains Volume accounts for the 60%-70% of the sand grains total volume；When carrying out the middle scale pressure break, the volume of the sand grains accounts for the 75%-80% of the sand grains total volume.
- 7. according to the method described in claim 1, it is characterized in that, a diameter of preforation tunnel diameter of the ball sealer 1-2 times, density 1.1-1.2g/cm3。
- 8. the according to the method described in claim 1, it is characterized in that, ball sealer put into the target coal seam gas well Number can be obtained according to the following formula：Wherein, n is the second predetermined amount；Any values of the k between 1.1-1.2；M is the number of the preforation tunnel.
- 9. according to the method described in claim 1, it is characterized in that, in the step b, the volume of the active water fracturing fluid For 10-12m3, discharge capacity is by 1m3/ min progressively increases to 2m3/min。
- 10. according to the method described in claim 1, it is characterized in that, treat that the ball sealer leaves the preforation tunnel and falls into well Behind bottom, open flow, sand washing operation are carried out successively, then the ball sealer is returned again and drains into ground, is completed to the target coal seam gas The secondary fracturing of well.
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