CN106321046B - A kind of low air permeability coal seam underground water sand pressure break gas pumping method - Google Patents
A kind of low air permeability coal seam underground water sand pressure break gas pumping method Download PDFInfo
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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
- E21B43/006—Production of coal-bed methane
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B33/00—Sealing or packing boreholes or wells
- E21B33/10—Sealing or packing boreholes or wells in the borehole
- E21B33/13—Methods or devices for cementing, for plugging holes, crevices or the like
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- 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
- E21B43/261—Separate steps of (1) cementing, plugging or consolidating and (2) fracturing or attacking the formation
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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
- E21B43/267—Methods for stimulating production by forming crevices or fractures reinforcing fractures by propping
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21F—SAFETY DEVICES, TRANSPORT, FILLING-UP, RESCUE, VENTILATION, OR DRAINING IN OR OF MINES OR TUNNELS
- E21F16/00—Drainage
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK 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
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Abstract
A kind of low air permeability coal seam underground water sand pressure break gas pumping method, it is therefore an objective to make gas cavity section communicate with each other, improve gas permeability of coal seam；The method of the present invention is to carry out extraction of drilling again after carrying out water sand pressure break from the lane floor rock Yu Chou to return airway construction water sand fracturing borehole；If maximum pressure is in 35MPa hereinafter, carrying out sealing of hole by the way of capsule sealing of hole；After starting fracturing pump, prepad fluid is injected into construction coal；Start to inject load fluid after coal seam fracture is formed and reaches requirement, stops injection when operation pressure rapid increase；Continue to inject prepad fluid and carry out coal seam pressure compensation again, drop to 10Mp to liquid operation pressure, re-inject load fluid, when operation pressure rapid increase stops injection；It is then poured into displacement fluid；After closing well head etc. to coal seam pressure slow release, hole flushing is carried out to pressure break hole with high pressure water；Region draining；Capsule sealing of hole is used when such as pressure break, is taken out capsule and is carried out sealing of hole, access extraction pipeline carries out extraction.
Description
Technical field
The present invention relates to one kind to be pressed into coal seam for high pressure fracture liquid and proppant by fracturing technology in underground, enhances coal
Layer gas permeability, the method for improving gas drainage under suction effect.
Background technique
For a long time, coal mine gas disaster is always an important factor for restricting coal enterprise's safe and efficient production.Because of gas
The number of death by accident accounts for 70% or more of coal mine total toll, and it is great, serious accident is mostly related with gas.Now with
China's coal-mine is gradually to deep mining, and mine gas pressure, gas bearing capacity constantly increase, shared by highly gassy mine and projecting mine
Ratio is continuously increased.From the point of view of current technology, gas control most efficient method is first to take out to adopt afterwards, however, low-permeable coal
Layer seriously constrains gas pumping effect, affects Safety of Coal Mine Production.Therefore, implement water sand pressure break to low air permeability coal seam to apply
Work technical research, carries out that this coal bed fracturing is anti-reflection, forms new extraction technique, and it is significant to improve coal bed gas extraction effect.
Summary of the invention
Object of the present invention is to overcome the shortcomings of above-mentioned prior art, one kind is provided gas cavity section can be made to communicate with each other and reach
To water conservancy diversion purpose, improve the gas permeability in coal seam and the low air permeability coal seam underground water sand pressure break gas pumping method of extracting result.
The method of the present invention is:
(1) drill pattern and construction: it constructs water sand fracturing borehole from the lane floor rock Yu Chou to return airway, into
Extraction of drilling is carried out again after row water sand pressure break；The lane floor rock Yu Chou (rock gangway) section sealing of hole effect is better than coal road section；
(2) sealing of hole: if construction maximum working pressure is in 35MPa hereinafter, carrying out sealing of hole, capsule by the way of capsule sealing of hole
Hole packer requires compression strength to reach 40MPa or more, and flare factor is greater than 150%, and single-unit packing element length is not less than 1 m；If wearing layer
The rock section of drilling is greater than 20 m and operation pressure is more than 35MPa, then uses cement mortar sealing of hole, cement mortar sealing of hole segment length
Not less than 20 m；
(3) prepad fluid injects: after starting fracturing pump, prepad fluid being injected construction coal, liquid injection rate far surpasses it in coal
Leakage rate in layer, so slowly boosting, after the liquid pump injection pressure power of fracturing pump discharge reaches coal seam reservoirs geology fracture pressure,
It forces coal seam to be softened to form crack, continues pump note fracturing fluid, crack can be expanded until reaching the ideal penetration of fracture and width
Spend range；Prepad fluid injection rate is generally 80-100m3；
The prepad fluid is clear water or active water fracturing fluid, the proportion of active water fracturing fluid by mass percentage are as follows: living
Property agent 0.04-0.07%, thickener 0.04-0.07%, KCl 0.3-0.7%, remaining is clear water；
(4) load fluid injects: after coal seam fracture is formed and reach requirement, fluid pressure it is steady after start that injection is initial to take sand
Liquid；Weight ratio shared by quartz sand is 3%-5% in initial load fluid；Quartz sand uses partial size for 0.15-0.30 mm quartz sand；When
Occur that injection initial load fluid should be temporarily ceased when operation pressure rapid increase；
(5) prepad fluid and load fluid are re-injected: continuing to inject prepad fluid carrying out coal seam pressure compensation again and split with expanded support
Seam, when liquid operation pressure drops to 10MPa and keeps stablizing, injects secondary load fluid；Quartz sand used in secondary load fluid
It is the middle grain quartz sand that partial size is 0.45-0.9mm, weight ratio shared by quartz sand is 8-11% in secondary load fluid；If operation pressure
Occur stopping injecting secondary load fluid when rapid increase；
(5) displacement fluid injects: load fluid, which has filled, followed by continues to inject displacement fluid, injection pressure 15-18MPa, note
Entering liquid measure is 2-3m3；To enter remaining sand grains in equipment pipe and pressure break hole in the coal body crack pressed off, it is unlikely to
The extracting result in plug-hole influence later period；After displacement fluid injection, fracturing work is completed；
(6) it hole flushing: after closing well head etc. to coal seam pressure slow release, is carried out with the high pressure water of 1-2MPa using pressure break hole
Hole flushing operation；Stop hole flushing when there was only a small amount of coal grain or sand grains is discharged；The general hole flushing time is 5-8 minutes；
(7) drain: because the fracturing borehole constructed in the lane bottom plate Yu Chou is elevation angle hole, high pressure water can be from coal hole freely
Outflow, need to carry out the drainage works of pressure break hole region, and as necessary by constructing, dedicated drainage ditch is drained；
(8) sealing of hole union extraction: if when pressure break use capsule sealing of hole, need take out capsule after by existing extraction borehole sealing of hole
Mode carries out sealing of hole, it is ensured that access extraction pipeline carries out extraction after sealing of hole is qualified；There are connect accordingly on the drainage tube of aperture
Mouthful, the test of the parameters such as extraction concentration, flow can be carried out；If it is cement mortar sealing of hole, accessed by reducer union existing
Extraction pipeline carries out extraction.
It is 35 MPa of pressing crack construction pressure limiting, it cannot termination of pumping without reason in fracturing pump injection process.If gone out during adding sand
Existing load fluid pressure oscillation is excessive, need to adjust weight ratio shared by quartz sand in injection load fluid, the weight ratio of sand is made to reduce or use
Clear water is counter to be arranged；If pressure break pump discharge head continuous high-pressure in fracturing process, load fluid injection rate but very little then reduces sand ratio,
It is repeated multiple times to build the pressure under fracturing pump maximum working pressure；If still amount of liquid is discharged in high pressure and fracturing pump to pressure break pump discharge head
Very little then considers that termination of pumping checks whether pipeline blocks, dredges pipeline pressure break again if blocking, otherwise, carries out union extraction.
Once discovery gas density transfinites in fracturing process, then stop operation immediately, relevant staff dismisses from the post safety
Place.(5 minutes) periodic sample at regular intervals monitors the silt concertation of load fluid, presses to analyze and determine in time
The reason of fluctuation or continuous high-pressure.
High pressure fracture liquid and proppant are pressed into coal seam by the present invention, overcome minimum principal stress, the rupture pressure more than coal petrography
Power and clossing pressure cause crack and extend, so that gas cavity section is communicated with each other and reach so that original plane of weakness opens in coal seam
To the purpose of water conservancy diversion, the gas permeability and extracting result in coal seam are improved, eliminates Gas Disaster to greatest extent.
Specific embodiment
One, prepare before pressure break
1, the installation, debugging of fracturing unit and material prepare；Water sand pressure break equipment is made of equipment train, there is pump respectively
Several equipment trains such as sled, mulling sled, motor are prized, match crowbar, shifting becomes sled, tool is prized, water tank is prized and sand loading is prized.Water sand pressure break
Equipment is mounted in the intake of underground, is no less than 200 m away from pressure break place, and the tunnel of installation site will have enough skies
Between and exit passageway, tunnel it is as gentle as possible.
Equipment operation inspection must be carried out before pressing crack construction.Aperture pipe valve is closed, to all construction pipes
Line carries out highest pressure limiting test.Under highest pressure limiting, pressure, which is stablized, is at least up to the time that technique initialization requires, and system equipment does not have
There is leakage, just illustrates that equipment and injected system are qualified, can construct, otherwise must be fastened or be replaced associated components.
Fracturing fluid needed for preparing enough pressure break before construction, proppant and equipment operation tool.
2, observation and parameter testing before pressure break；It, can be according to pressure break place difference, selection before pressure break to investigate fracturing effect
Property test hundred meters of drilling gas flows, drilling flux depression coefficient, Permeability Coefficent in Coal Seam, K1 value, coal powder quantity of bore, a, b value examination, △
P, the relevant parameters such as f value.Conscientiously observe the pattern in 100 tunnels m of pressure break hole or so, the construction especially more developed nearby and
Coal body fracture development area.Meanwhile roof and floor support conditions are conscientiously observed, forbid to carry out pressure break in empty top zone.
3, drill pattern and construction；According to pressure break place difference and gas region difference is administered using different pressure breaks
Pattern is applied using the lane floor rock Yu Chou (rock gangway) to return airway because rock gangway section sealing of hole effect is better than coal road section
Work water sand fracturing borehole carries out extraction of drilling after carrying out water sand pressure break again.
4, sealing of hole；Sealing of hole is carried out with capsule hole or cement mortar, capsule hole requires compression strength to reach 40MPa
More than, flare factor is greater than 150%, and single-unit packing element length is not less than 1 m.Project under construction design maximum working pressure 35MPa with
Under operation it is tentative by the way of capsule sealing of hole.If when layer-through drilling rock section is greater than 20 m, and operation pressure is more than 35MPa
Construction operation, then use cement mortar sealing of hole；Drilling carries out cement mortar sealing of hole, cement mortar sealing of hole segment length in petrosal foramen
Not less than 20 m.
Two, pressure break is implemented
1, the selection of fracturing fluid；Fracturing unit is exactly formed by highly pressurised liquid energy transmission by the main function of fracturing fluid
Into coal seam reservoirs, new crack is caused in coal seam reservoirs, is strutted or is expanded primary fracture, proppant is then added to crack
In, cancelling rear support agent when pressure ensure that crack will not be closed.In fracturing process, fracturing fluid is pressed into the program point in coal seam
It Wei not prepad fluid, load fluid, displacement fluid.
The basic principle of fracturing fluid selection has:
(1) good with the compatibility of water source and coal seam reservoirs；
(2) leak-off is low, fluid efficiency is high, can make slit；
(3) prop-carrying capacity is strong；
(4) frictional resistance is low, has good stability；
(5) residue is low, is easy the row of returning；
(6) source of goods is wide, and price is low.
By comparing to active water fracturing fluid, gelled fracturing fluid and clean fracturing fluid, the adaptability of different fracturing fluids is obtained;
Comprehensively considered, select active water as fracturing fluid, its advantage is that simple with liquid, low, at low cost to coal seam injury etc..
2, the selection of proppant；The purpose of hydraulic fracturing is to become to be connected with pit shaft by the radial flow for coming together in pit shaft
Water conservancy diversion crack in linear flow, the flow conductivity in crack must be far longer than the flow conductivity in stratum, to obtain hypertonic
The crack of saturating rate, it is necessary to proppant be added, the effect of proppant is two walls of supporting crack, to terminate in pressing crack construction
Afterwards, bottom pressure drops to less than coal seam fracture clossing pressure, and the water conservancy diversion crack that wellbore is led to caused by fracturing work is still protected
Hold opening.The flow conductivity in crack, which will at least arrive greatly, can eliminate most of radial flows of underground and linear flow is allowed to enter from reservoir
Into crack, to reach this purpose, it is necessary to make the orders of magnitude several greatly of the permeability ratio reservoir permeability in supporting crack.It is used
Proppant be broadly divided into three categories: natural siliceous sand, artificial porcelain granule and resin covering processing proppant.
(1) quartz sand；Quartz sand is the natural stability mineral that a kind of distribution is wide, hardness is big, main chemical compositions
For silica, desert, river shoal or coastal area are mainly originated in, mineral constituent is based on quartz, and quartz content is generally 80%
Or so, quartz content is up to 98% or more in external high grade quartz sand.Quartz sand particle relative density is about 2.65 or so, volume
Density is about in 1.75 g/cm3.For the reservoir of low clossing pressure, quartz sand is used to achieve one as pressure break with proppant
Fixed effect of increasing production.The relative density of quartz sand is lower, and cheap convenient for construction pumping, thus in shallow well so far still
It is widely used.
(2) haydite；It can be made with electrolysis or firing, have compression strength big, be mainly used for clossing pressure in 34-59
Pressing crack construction operation in MPa can guarantee the flow conductivity with higher under high clossing pressure.But relative density is also larger,
There is higher requirement to the performance (such as viscosity, rheological characteristic) and pumping conditions (such as discharge capacity, plant capacity etc.) of fracturing fluid, separately
The production cost of outer haydite is relatively high.Both factors cause the pressing crack construction of haydite expensive, limit making extensively for it
With.
(3) resin covering sand；The proppant that, flow conductivity low for natural siliceous sand compression strength is poor and develops uses
Special process wraps up modified phenol formaldehyde resin onto the surface of quartz sand, and is made through thermosetting processing.Generally its particle
Density is 2.55 g/cm3, slightly lighter than quartz sand.Due to having wrapped up one layer of high-intensity resin in sand surface, make clossing pressure point
Cloth reduces point load, its forced area diameter of the particle of no resin film is particle diameter on the area of biggish resin layer
10% or smaller, and have its forced area diameter of the particle of resin film close to the 40% of particle diameter；Use electron microscope observation
It was found that the contact area of deformable proppant increases 16 times than the contact area of easy fragmentation proppant.Accordingly even when having crushed packet
Fragment, particle can be still bundled together by the sand in layer, the resin layer of outside, prevent them from migrating or blocking proppant band
Hole, maintain crack compared with high flow conductivity.
The characteristics of resin covering sand: the resistant to breakage ability of sand grains is improved, and sand grains is bonded together, and not only forms
One has the filter layer of penetrating power, and the phenomenon that prevent proppant to spue, reduce proppant embedment stratum.Due to
Every granule grain has one layer of tough and tensile resin enclosure, therefore, generated if sand grains is crushed under certain closure stress
Clast, fine silt are but coated in resin shell, to prevent the migration of clast, fine silt.Even if being thus crushed in sand grains
In the case where, which still has certain flow conductivity.
Which kind of specifically used proppant will according to the coal bed texture of project under construction, condition, etc. factors comprehensively considered progress
Detail design, recommendation select to use quartz sand (partial size has particulate, middle grain and coarse grain respectively) as proppant material, its advantage is that
Moderate performance, the cheap and source of goods are wide etc..
3, prepad fluid injects；After starting fracturing pump, by the active water fracturing fluid injection construction target coal seam of configuration, liquid pressure
Power is slowly boosted, after pump injection pressure power, which reaches fracture pressure, forms crack, continue pump note, fluid pressure keeps high pressure or appearance
Several minor peaks, until pump fluence reaches design requirement dosage, about 80-100m3, pump pressure meeting is in a slight decrease and keeps stable；It is living
The proportion of property water fracturing fluid by mass percentage are as follows: activating agent 0.04-0.07%, thickener 0.04-0.07%, KCl 0.3-
0.7%, remaining is clear water.Low foaming surfactant can be selected in activating agent, and water-based thickener can be selected in thickener.
4, load fluid injects；The prepad fluid later period is injected, after formation fracture is formed, starts to inject load fluid, partial size, which is added, is
0.15-0.30 mm quartz sand, sand ratio are 3% ~ 5%.If operation pressure rapid increase, bird's eye gravel sand was both stopped and has added sand, had continued
Active water fracturing fluid is injected, when pressure to be onstructed drops to 10Mp and keeps stablizing, restarts to add sand.Quartzy sand grains at this time
Diameter should be the middle grain quartz sand of 0.45-0.9mm, and average sand ratio is advisable for 10% or so.In the injection load fluid later period, if construction pressure
Power rapid increase need to carry out stopping adding sand or flushing.
5, displacement fluid injects；After flushing, starting to inject displacement fluid, injection pressure is tentatively set to 15-18MPa, so as to
Enter remaining sand grains in hole in the coal body crack pressed off, being unlikely to plug-hole influences the extracting result in later period.Inject liquid measure
For 2-3m3。
6, hole flushing；After displacement fluid injection, well head is closed, is waited after slowly unloading release to coal seam pressure, with the high pressure of 1 ~ 2MPa
Water conservancy carries out hole flushing operation with pressure break hole.Stop hole flushing when there was only a small amount of coal grain or sand grains is discharged, the general hole flushing time is 5-8
min。
7, it drains；Because being elevation angle hole in the fracturing borehole that the lane bottom plate Yu Chou is constructed, high pressure water can be from coal hole freely
Outflow, need to carry out the drainage works of pressure break hole region, the dedicated drainage ditch that can construct when necessary is drained.
8, data inputting；It is stringent to record pressure break pump discharge head, flow, liquid measure, sand to each stage in fracturing process
The data such as amount, sand ratio, time, and fill in special record form.
9, abnormality processing:
(1) 35 MPa of pressing crack construction pressure limiting, mustn't termination of pumping without reason in fracturing pump injection process；
(2) it is fluctuated if there is pressure break pump discharge head, then adjusts injection sand ratio, make sand than reducing or being arranged with clear water is counter；
(3) if pressure break pump discharge head continuous high-pressure, fracturing fluid injection rate very little then reduce sand ratio in fracturing process,
It is repeated multiple times to build the pressure under maximum working pressure.If pressure break pump discharge head still high pressure and injection rate very little, consider that termination of pumping is examined
It checks whether road blocks, dredges pipeline pressure break again if blocking, otherwise, carry out union extraction；
(4) once discovery gas density transfinites in fracturing process, then termination of pumping immediately, correlation test personnel withdraw to safely
Point；
(5), there is pressure wave to analyze in time in the silt concertation for wanting periodic sample (every 5 minutes) monitoring fracturing fluid
The reason of situations such as dynamic, continuous high-pressure.
Three, pressure break terminates
1, observation and parameter testing after pressure break；Test after pressure break with Gas explosion burns corresponding before pressure break, meanwhile, observe
The pattern in 100 tunnel m of pressure break hole or so after pressure break, the construction especially more developed nearby and coal body fracture development area, see
Survey whether coal wall has situations such as water outlet, roadway deformation.And with compared before pressure break, primarily determine fracturing effect and pressure break radius.Such as
Fruit need to investigate pressure break radius, then construction drill is tested in pressure break range areas, the Gas explosion burns before comparing pressure break, thus
Accurately determine pressure break radius.
2, sealing of hole union extraction；When pressure break if capsule sealing of hole then need take out capsule after by existing extraction borehole sealing of hole mode
Carry out sealing of hole, it is ensured that sealing of hole is qualified, accesses extraction pipeline later and carries out extraction.Meanwhile there are corresponding on the drainage tube of aperture
Interface can carry out the test of the parameters such as extraction concentration, flow；If it is cement mortar sealing of hole, accessed by reducer union existing
Extraction pipeline carries out extraction.
3, extraction parameter testing；Gas density, extraction negative pressure, extraction stream in detail after record fracturing borehole union extraction
The related extraction parameter such as amount, compares the extraction situation of the non-fracturing borehole in proximate region, investigates extracting result.By investigating different pressures
The extraction situation of drilling is split, the final qualitative and quantification for realizing fracturing parameter and extracting result is expressed, and is mentioned for pressure break in the future
For guidance.
Claims (6)
1. a kind of low air permeability coal seam underground water sand pressure break gas pumping method, it is characterized in that:
(1) drill pattern and construction: from the lane floor rock Yu Chou to return airway construction water sand fracturing borehole, carrying out water
Extraction of drilling is carried out after sand pressure break again；The lane floor rock Yu Chou section sealing of hole effect is better than coal road section；
(2) sealing of hole: if construction maximum working pressure in 35MPa hereinafter, carry out sealing of hole by the way of capsule sealing of hole, capsule sealing of hole
Device requires compression strength to reach 40MPa or more, and flare factor is greater than 150%, and single-unit packing element length is not less than 1 m；If layer-through drilling
Rock section to be greater than 20 m and operation pressure be more than 35MPa, then using cement mortar sealing of hole, cement mortar sealing of hole segment length is not small
In 20 m；
(3) prepad fluid injects: after starting fracturing pump, prepad fluid being injected construction coal, liquid injection rate far surpasses it in coal seam
Leakage rate, so slowly boosting, when fracturing pump discharge liquid pump injection pressure power reach coal seam reservoirs geology fracture pressure after, force
Coal seam is softened to form crack, continues pump note fracturing fluid, expands crack until reaching the ideal penetration of fracture and width range；Before
Setting liquid injection rate is 80-100m3；The prepad fluid is clear water or active water fracturing fluid；
(4) load fluid injects: after coal seam fracture is formed and reach requirement, fluid pressure it is steady after start to inject initial load fluid；
Weight ratio shared by quartz sand is 3%-5% in initial load fluid；Quartz sand uses partial size for 0.15-0.30 mm quartz sand；Work as appearance
Injection initial load fluid should be temporarily ceased when operation pressure rapid increase；
(5) prepad fluid and load fluid are re-injected: continuing to inject prepad fluid and carries out coal seam pressure compensation again with expanded support crack, to
When liquid operation pressure drops to 10MPa and keeps stablizing, secondary load fluid is injected；Quartz sand used in secondary load fluid is partial size
For the middle grain quartz sand of 0.45-0.9mm, weight ratio shared by quartz sand is 8-11% in secondary load fluid；If operation pressure occurs fast
Stop injecting secondary load fluid when speed rises；
(5) displacement fluid injects: load fluid, which has filled, followed by continues to inject displacement fluid, and injection pressure 15-18MPa injects liquid
Amount is 2-3m3；To enter remaining sand grains in equipment pipe and pressure break hole in the coal body crack pressed off, it is unlikely to plug-hole
Influence the extracting result in later period；After displacement fluid injection, fracturing work is completed；
(6) hole flushing: after closing well head etc. to coal seam pressure slow release, hole flushing is carried out using pressure break hole with the high pressure water of 1-2MPa
Operation；Stop hole flushing when there was only a small amount of coal grain or sand grains is discharged；The hole flushing time is 5-8 min；
(7) drain: because the fracturing borehole constructed in the lane bottom plate Yu Chou is elevation angle hole, high pressure water is freely flowed out from coal hole,
The drainage works that pressure break hole region need to be carried out are drained by construction drainage canal；
(8) sealing of hole union extraction: if when pressure break use capsule sealing of hole, need take out capsule after by existing extraction borehole sealing of hole mode
Carry out sealing of hole, it is ensured that access extraction pipeline carries out extraction after sealing of hole is qualified；There are corresponding interface on the drainage tube of aperture, into
The test of row extraction concentration, flow parameter；If it is cement mortar sealing of hole, by reducer union access existing extraction pipeline into
Row extraction.
2. water sand pressure break gas pumping method in low air permeability coal seam underground as described in claim 1, it is characterized in that the activity
The proportion of water fracturing fluid by mass percentage are as follows: activating agent 0.04-0.07%, thickener 0.04-0.07%, KCl 0.3-
0.7%, remaining is clear water.
3. water sand pressure break gas pumping method in low air permeability coal seam underground as claimed in claim 1 or 2, it is characterized in that adding sand
It is excessive if there is load fluid pressure oscillation in the process, weight ratio shared by quartz sand in injection load fluid need to be adjusted, the weight of sand is made
Amount is than reducing or being arranged with clear water is counter；If pressure break pump discharge head continuous high-pressure in fracturing process, load fluid injection rate is small, then reduces
Sand ratio, it is repeated multiple times to build the pressure under fracturing pump maximum working pressure；If still high pressure and fracturing pump are discharged pressure break pump discharge head
Amount of liquid is small, then considers that termination of pumping checks whether pipeline blocks, dredge pipeline pressure break again if blocking, otherwise, carry out union pumping
It adopts.
4. water sand pressure break gas pumping method in low air permeability coal seam underground as claimed in claim 1 or 2, it is characterized in that in pressure break
In the process once discovery gas density transfinites, then stop operation immediately, relevant staff withdraws safety place to.
5. water sand pressure break gas pumping method in low air permeability coal seam underground as claimed in claim 1 or 2, it is characterized in that will be every
There is pressure oscillation or continuous high-pressure to analyze and determine in time in the silt concertation of time period sampling monitoring load fluid
The reason of.
6. water sand pressure break gas pumping method in low air permeability coal seam underground as claimed in claim 1 or 2, it is characterized in that pressure break is applied
35 MPa of work pressure limiting, cannot termination of pumping without reason in fracturing pump injection process.
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| CN201610792384.4A CN106321046B (en) | 2016-08-31 | 2016-08-31 | A kind of low air permeability coal seam underground water sand pressure break gas pumping method |
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| CN106321046B true CN106321046B (en) | 2019-01-29 |
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| CN108868871B (en) * | 2018-05-18 | 2024-03-29 | 河南能源化工集团研究总院有限公司 | Method for quickly balancing stress after hydraulic punching |
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| CN111237007A (en) * | 2020-02-19 | 2020-06-05 | 中煤科工集团重庆研究院有限公司 | Hydraulic fracturing method for underground deep low-permeability coal reservoir |
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| CN112377242B (en) * | 2020-11-16 | 2022-05-13 | 中煤科工集团重庆研究院有限公司 | Method for synchronously extracting and displacing gas in soft coal seam by repeated hydraulic fracturing |
| CN113338883B (en) * | 2021-05-06 | 2022-08-19 | 山东科技大学 | Fracturing fluid reinforced flowback method based on ultrasonic cavitation effect |
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