CN113250670B - Single-hole multi-section synchronous control fracturing coal body permeability increasing system and method - Google Patents
Single-hole multi-section synchronous control fracturing coal body permeability increasing system and method Download PDFInfo
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- CN113250670B CN113250670B CN202110515692.3A CN202110515692A CN113250670B CN 113250670 B CN113250670 B CN 113250670B CN 202110515692 A CN202110515692 A CN 202110515692A CN 113250670 B CN113250670 B CN 113250670B
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- 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
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- 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
- 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 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
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- 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
- 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 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
- E21B43/30—Specific pattern of wells, e.g. optimizing the spacing of wells
Abstract
The invention discloses a single-hole multi-section synchronous control fracturing coal body permeability increasing system which comprises a water diversion fracturing device, a grouting device, a ball valve, a T-shaped three-way valve and an overflow device, wherein the water diversion fracturing device is connected with the ball valve; the water diversion fracturing device comprises a liquid storage tank, a liquid conveying pipe, a high-pressure pump, a high-pressure rubber pipe, a water diversion tank, a high-pressure water inlet rubber pipe, a plugging flange plate, a high-pressure water injection seamless steel pipe, a third fracturing bag, a second fracturing bag and a first fracturing bag; the grouting device comprises a grouting pump, a grouting pump pressure gauge, a grouting pressure regulating valve and a grouting pipe; the overflow device comprises an overflow valve, an overflow regulating valve and an overflow valve pressure gauge. The invention also provides a single-hole multi-section synchronous control fracturing coal body permeability increasing method. The invention not only can carry out multi-point fracturing on the fracturing drilled hole and greatly improve the air permeability of the coal bed, but also has simple construction process and can realize the generation of more fracturing fractures under the condition of small flow injection.
Description
Technical Field
The invention relates to the technical field of permeability improvement of a low-permeability coal seam in a coal mine, in particular to a single-hole multi-section synchronous control fracturing coal body permeability improvement system and method.
Background
In high gas and outburst mines in China, coal beds generally have the characteristics of complex occurrence conditions and low air permeability. Along with the continuous increase of the mining depth of the coal seam, the densification degree of the coal seam is further intensified due to the increase of the ground stress, so that the air permeability of the coal seam is extremely poor, and on the other hand, the original gas content of deep coal bodies is large, so that the difficulty of gas extraction of the deep coal bodies is large, the extraction efficiency is low, and the safe and efficient mining of a mine is greatly influenced.
Aiming at the current situation, the permeability increase of the low permeability coal seam is a measure which needs to be taken before the extraction of the coal seam. The hydraulic fracturing technology is an effective permeability-increasing technology for a low-permeability coal bed, and the main principle is that water is injected into a pore diameter by using high-pressure pumping equipment at a quantity far exceeding the permeability of a coal body, so that high pressure is held, cracks are formed in the coal bed, and the air permeability of the coal bed is improved.
Traditional hydraulic fracturing is to carry out fracturing to whole drilling after the hole sealing of drilling, though this kind of fracturing mode simple process, nevertheless because drilling is longer, and it is great to ooze the water flow, must ask the high-pressure pump to have great flow under the prerequisite of guaranteeing output pressure, therefore the pump station is bulky, the limited operation space in the unsuitable pit. Meanwhile, in the traditional hydraulic fracturing, after a certain point of a drilled hole is cracked, cracks mainly expand along the cracking point, cracks in other places are relatively weak in expansion, the total number of the cracks is small, and the gas permeability of a coal body is limited. The staged point type hydraulic fracturing technology utilizes special fracturing equipment to fracture a fracturing drill hole one by one from inside to outside, and the fracturing mode has the advantages of more coal body cracks, better anti-reflection effect, smaller required water flow, more complex process, more time consumption in the one-by-one fracturing process and lower fracturing efficiency.
Disclosure of Invention
In order to solve the technical problems, the invention aims to provide a single-hole multi-section synchronous control fracturing coal body permeability increasing system and a single-hole multi-section synchronous control fracturing coal body permeability increasing method, which can be used for implementing multi-point fracturing on a fracturing drill hole, greatly improving the air permeability of a coal seam, being simple in construction process and capable of generating more fracturing fractures under the condition of small-flow injection.
The above object of the present invention is achieved by the following technical solutions: the single-hole multi-section synchronous control fracturing coal body permeability increasing system comprises a water diversion fracturing device, a grouting device, a ball valve, a T-shaped three-way valve and an overflow device;
the water diversion fracturing device comprises a liquid storage tank, a liquid conveying pipe, a high-pressure pump, a high-pressure rubber pipe, a water diversion tank, a high-pressure water inlet rubber pipe, a plugging flange plate, a high-pressure water injection seamless steel pipe, a third fracturing bag, a second fracturing bag and a first fracturing bag; the liquid storage tank is connected with the high-pressure pump through a liquid conveying pipe, the water distribution tank is provided with a high-pressure water inlet and three high-pressure water distribution interfaces, and each high-pressure water distribution interface is independently provided with a high-pressure gauge and a water distribution valve; the high-pressure pump is connected with a high-pressure water inlet of the water distribution box through a high-pressure rubber pipe; the plugging flange plate is provided with three water inlet interfaces and one grouting port interface, and one end of each water inlet interface is connected with the three high-pressure water distribution interfaces of the water distribution box through a high-pressure water inlet rubber pipe; the other end of the three-way water inlet interface is respectively connected with three-way water inlets of the third fracturing bag through a high-pressure water injection seamless steel pipe and a high-pressure water injection pipe joint, two water inlets of the three-way water inlets of the third fracturing bag are respectively connected with two water inlets of the second fracturing bag through a high-pressure water injection seamless steel pipe and a high-pressure water injection pipe joint, and one water inlet of the two water inlets of the second fracturing bag is respectively connected with one water inlet of the first fracturing bag through a high-pressure water injection seamless steel pipe and a high-pressure water injection pipe joint;
one end of a grouting opening interface on the plugging flange plate is connected with the ball valve through a high-pressure rubber pipe, the ball valve is connected with an A interface of the T-shaped three-way valve through the high-pressure rubber pipe, a B interface of the T-shaped three-way valve is connected with the grouting device through the high-pressure rubber pipe, the grouting device is used for injecting cement mortar into a fracturing drill hole, and a C interface of the T-shaped three-way valve is connected with the overflow device through the high-pressure rubber pipe.
Furthermore, a hole sealing sleeve is welded and fixed on the sealing flange plate and used for sealing a fracturing drill hole.
Furthermore, a fracturing bag bursting valve is respectively arranged on the third fracturing bag, the second fracturing bag and the first fracturing bag.
Furthermore, the distance between the first fracturing bag, the second fracturing bag and the third fracturing bag is twice the fracturing radius, and the distance between the third fracturing bag and the three-way water inlet interface is larger than the width of a roadway loosening ring.
Further, the bursting pressure of the fracturing bag bursting valve is 10 MPa.
Furthermore, a pressure relief valve and a pressure relief outlet are further arranged on the water distribution box and used for discharging high-pressure water at the fracturing bag in the fracturing drill hole through the pressure relief outlet.
Further, the grouting device includes grouting pump, grouting pump manometer, slip casting pressure regulating valve and slip casting pipe, set up grouting pump manometer and slip casting pressure regulating valve on the grouting pump, the B interface of T type three-way valve is connected with the grout outlet of grouting pump through the rubber tube, the slip casting pipe with the other end of the slip casting mouth interface of the same way on the shutoff ring flange is connected to stretch into to the fracturing drilling.
Further, the overflow device comprises an overflow valve, an overflow regulating valve and an overflow valve pressure gauge, wherein an inlet of the overflow valve is connected with a C connector of the T-shaped three-way valve through a high-pressure rubber pipe, the overflow valve is provided with the overflow regulating valve and the overflow valve pressure gauge, the overflow regulating valve is used for regulating overflow pressure, and the overflow pressure gauge 13 is used for detecting fluid pressure at the inlet of the overflow valve in real time.
The invention also provides a single-hole multi-section synchronous control fracturing coal body permeability increasing method, which uses the single-hole multi-section synchronous control fracturing coal body permeability increasing system, and comprises the following steps:
step 1, constructing bedding fracturing drill holes along the coal seam trend in a bedding way of an underground working face, constructing monitoring holes with the same angle as the fracturing holes at the periphery of the fracturing holes according to the fracturing radius, and flushing coal scraps of the fracturing drill holes by utilizing underground compressed air after the drilling construction is finished;
step 5, adjusting the output pressure of a high-pressure pump to be 5MPa, opening a water distribution valve of a water distribution box to control a first fracturing bag, starting the high-pressure pump, controlling the water flow to be slowly injected into a high-pressure pipeline connected with the first fracturing bag, slowly expanding the first fracturing bag, extruding slurry inside a fracturing drill hole due to expansion of the first fracturing bag to increase the pressure inside the fracturing drill hole, wherein the pressure exceeds the set pressure of an overflow valve by 3MPa, and cement mortar flows out of an overflow outlet of the overflow valve to ensure that the pressure inside the fracturing drill hole is 3 MPa; closing a shunt valve of the way after a high-pressure gauge on a shunt box corresponding to the first fracturing bag reaches 5MPa and keeps injecting for 5 min;
step 6, according to the mode provided in the step 5, sequentially boosting the pressure of high-pressure gauges on the water distribution boxes corresponding to the second fracturing bag and the third fracturing bag to 5MPa and keeping continuous injection for 5min, then closing the high-pressure pumps, closing the water distribution valves of all paths, and closing the ball valves; then, the overflow valve and the grouting pump are removed and cleaned; keeping the pressure in the fracturing drill hole at 3MPa, standing for 48 hours, and completely solidifying cement mortar in the fracturing drill hole;
step 7, after cement mortar in the fracturing drill hole is completely solidified, forming non-cement mortar fracturing spaces at the positions of the first fracturing bag, the second fracturing bag and the third fracturing bag, adjusting the injection pressure of the high-pressure pump to be 30MPa again, wherein the pressure is far greater than the blasting pressure of a blasting valve of the fracturing bag by 10MPa, opening each water diversion valve in the water diversion box, starting the high-pressure pump, simultaneously injecting high-pressure water into the first fracturing bag, the second fracturing bag and the third fracturing bag, opening each blasting valve of the fracturing bag along with the rise of the pressure, directly acting the high-pressure water on coal at the positions of the first fracturing bag, the second fracturing bag and the third fracturing bag, and starting cracking and continuously expanding cracks when the high-pressure water pressure reaches the cracking condition of the coal;
step 8, after a crack formed by one of the first fracturing bag, the second fracturing bag and the third fracturing bag is communicated with the monitoring hole, a high-pressure gauge on a water distribution box corresponding to the fracturing bag can display that the pressure drops greatly, and at the moment, a water distribution valve corresponding to the high-pressure gauge with the pressure dropping in the water distribution box is closed; the other two fracturing bags continue to fracture until fracturing fractures formed at all the fracturing bags are communicated with the monitoring holes, and then the fracturing process is finished; and closing the high-pressure pump, opening a pressure relief valve in the water distribution box, and releasing high-pressure water at the fracturing bag in the fracturing drill hole through a pressure relief outlet.
Further, the single-hole multi-section synchronous control fracturing coal body permeability increasing method further comprises the following steps:
and 9, after the step 8 is finished, the fracturing drill hole and the monitoring hole can be connected to an extraction pipeline for extraction.
Compared with the prior art, the invention has the beneficial effects that:
1. the technology integrates the advantages of traditional hydraulic fracturing and sectional point type hydraulic fracturing permeability increase, and provides a single-hole multi-section synchronous control fracturing permeability increase technology which takes an expanded fracturing bag to provide a fracturing space and takes cement mortar as a hole sealing medium to perform fracturing control by a multi-path water dividing box aiming at the problems of few cracks, more seepage water flow and long fracturing time generated by the traditional hydraulic fracturing and the problems of complex implementation process and low fracturing efficiency of the sectional point type hydraulic fracturing.
2. The water diversion fracturing device adopts the fracturing bag with low cost and the seamless steel pipe as main consumables, realizes low-cost disposable utilization, compares segmentation point type hydraulic fracturing consumptive material loss, and economic nature is better, and operation simple process can effectively improve safety and production efficiency.
Drawings
The invention is further described with reference to the following figures and detailed description.
FIG. 1 is a schematic structural diagram of a single-hole multi-stage synchronous control fracturing coal body permeability increasing system of the invention;
FIG. 2 is a schematic diagram of a drilling arrangement of a single-hole multi-section synchronous control fracturing coal body permeability increasing system of the invention;
FIG. 3 is a flow chart of a single-hole multi-section synchronous control fracturing coal body permeability increasing method provided by the invention;
in the figure: 1, a liquid storage tank; 2, a transfusion tube; 3 a high pressure pump; 4, a high-pressure rubber pipe; 5 a pressure relief outlet; 6, unloading the pressure valve; 7, a high-pressure water inlet; 8, a water distributing valve; 9 high-pressure gauge; 10, dividing a water box; 11, a high-pressure water distribution interface; 12 high-pressure water inlet rubber pipe; 13 overflow valve pressure gauge; 14 relief valves; 15 grouting pump pressure gauge; 16 grouting pump; 17 grouting pressure regulating valve; an 18T-shaped three-way valve; 19 a ball valve; 20 an overflow regulating valve; 21 plugging the flange plate; 22 grouting port interface; 23 water inlet interface; 24 grouting pipes; 25 hole sealing sleeves; 26 high-pressure water injection seamless steel pipes; 27 high-pressure water injection pipe joint; number 28, three, fracturing the capsular bag; fracture pocket No. 29; fracturing the capsular bag No. 30; 31 fracturing the bladder burst valve; 32 fracturing the borehole; 33 an overflow outlet; the hole is monitored 34.
Detailed Description
The details and embodiments of the present invention are further illustrated in the accompanying drawings.
Example one
Referring to fig. 1, the single-hole multi-section synchronous control fracturing coal body permeability increasing system comprises a water diversion fracturing device, a grouting device, a ball valve 19, a T-shaped three-way valve 18 and an overflow device;
the water diversion fracturing device comprises a liquid storage tank 1, a liquid conveying pipe 2, a high-pressure pump 3, a high-pressure rubber pipe 4, a water diversion tank 10, a high-pressure water inlet rubber pipe 12, a blocking flange 21, a high-pressure water injection seamless steel pipe 26, a third fracturing bag 28, a second fracturing bag 29 and a first fracturing bag 30; the liquid storage tank 1 is connected with the high-pressure pump 3 through a liquid conveying pipe 2, the water distribution tank 10 is provided with a high-pressure water inlet 7 and three high-pressure water distribution interfaces 11, and each high-pressure water distribution interface 11 is independently provided with a high-pressure gauge 9 and a water distribution valve 8; the high-pressure pump 3 is connected with a high-pressure water inlet 7 of the water distribution box 10 through a high-pressure rubber pipe 4; the blocking flange 21 is provided with three water inlet interfaces 23 and one grouting port interface 22, and one end of each of the three water inlet interfaces 23 is connected with the three high-pressure water distribution interfaces 11 of the water distribution box 10 through a high-pressure water inlet rubber pipe 12; the other end of the three-way water inlet interface 23 is connected with three water inlets of the three fracturing bladder bag 28 through a high-pressure water injection seamless steel pipe 26 and a high-pressure water injection pipe joint 27, two water inlets of the three fracturing bladder bag 28 are connected with two water inlets of the two fracturing bladder bag 29 through a high-pressure water injection seamless steel pipe 26 and a high-pressure water injection pipe joint 27 (after two water inlets of the three fracturing bladder bag 28 are connected with two water outlets arranged on the three fracturing bladder bag 28 through a high-pressure water injection seamless steel pipe 26 and a high-pressure water injection pipe joint 27 respectively, the two water inlets are connected with two water inlets of the two fracturing bladder bag 29 through a high-pressure water injection seamless steel pipe 26 and a high-pressure water injection pipe joint 27), and one water inlet of the two water inlets of the two fracturing bladder bag 29 is connected with one water inlet of the one fracturing bladder bag 30 through a high-pressure water injection seamless steel pipe 26 and a high-pressure water injection pipe joint 27 respectively The water inlets are connected; (one of the two water inlets of the second fracturing bag 29 is connected with one water outlet of the second fracturing bag 29 through the high-pressure water injection seamless steel pipe 26 and the high-pressure water injection pipe connector 27, and then is connected with one water inlet of the first fracturing bag 29 through the high-pressure water injection seamless steel pipe 26 and the high-pressure water injection pipe connector 27)
One end of a grouting opening interface 22 on the plugging flange 21 is connected with a ball valve 19 through a high-pressure rubber pipe 4, the ball valve 19 is additionally connected with an interface A of the T-shaped three-way valve 18 through the high-pressure rubber pipe 4, an interface B of the T-shaped three-way valve 18 is connected with a grouting device through the high-pressure rubber pipe 4, the grouting device is used for injecting cement mortar into the fracturing drill hole 32, and an interface C of the T-shaped three-way valve 18 is connected with an overflow device through the high-pressure rubber pipe 4.
And a hole sealing sleeve 25 is further welded and fixed on the sealing flange 21 and used for sealing the fracturing drill hole 32.
And fracturing bag bursting valves 31 are respectively arranged on the third fracturing bag 28, the second fracturing bag 29 and the first fracturing bag 30.
In order to prevent premature intercommunication of the fracture cracks formed between the individual fracturing pockets, which results in reduced crack development, the spacing between the first, second and third fracturing pockets 30, 29, 28 is twice the fracture radius; in order to prevent a fracturing crack formed at the third fracturing bag 28 from communicating with a roadway loosening zone to cause fracturing pressure loss, the distance between the three water inlets of the third fracturing bag 28 and the three water inlet connectors 23 is larger than the width of the roadway loosening zone (generally not smaller than 15 m).
The bursting pressure of the fracturing bag bursting valve is 10 MPa.
The water distribution box 10 is also provided with a pressure relief valve 6 and a pressure relief outlet 5, and is used for discharging high-pressure water at the fracturing bag in the fracturing drill hole 32 through the pressure relief outlet 5.
The grouting device includes grouting pump 16, grouting pump manometer 15, slip casting pressure regulating valve 17 and slip casting pipe 24, set up grouting pump manometer 15 and slip casting pressure regulating valve 17 on the grouting pump 16, the B interface of T type three-way valve 18 is connected with the grout outlet of grouting pump 16 through the rubber tube, slip casting pipe 24 with the other end of the slip casting mouth interface 22 of the same way on the shutoff ring flange 21 is connected to stretch into to fracturing drilling 32.
The overflow device comprises an overflow valve 14, an overflow regulating valve 20 and an overflow valve pressure gauge 13, wherein the inlet of the overflow valve 14 is connected with a C connector of the T-shaped three-way valve 18 through a high-pressure rubber pipe 4, the overflow regulating valve 20 and the overflow valve pressure gauge 13 are arranged on the overflow valve 14, the overflow regulating valve 20 is used for regulating overflow pressure, and the overflow pressure gauge 13 is used for detecting the fluid pressure at the inlet of the overflow valve 14 in real time.
During grouting, an A interface of the T-shaped three-way valve 18 is communicated with a B interface, and a grouting pump 16 injects grout into a fracturing borehole 32. When the water is injected into the water diversion fracturing device to enable the fracturing bag to form a fracturing space, the interface A in the T-shaped three-way valve 18 is communicated with the interface C, and after the pressure of slurry in the fracturing drill hole 32 exceeds the set overflow pressure of the overflow valve 14 by 3MPa, the slurry is discharged from the overflow valve 14, and the internal pressure of the fracturing drill hole is kept at 3 MPa.
The system injects cement mortar into a fracturing drill hole 32 with pressure through a grouting device, the pressure is kept at 3MPa, then the hydraulic fracturing device injects water into a third fracturing bag 28, a second fracturing bag 29 and a first fracturing bag 30 in sequence with the pressure of 5MPa, the third fracturing bag 28, the second fracturing bag 29 and the first fracturing bag 30 expand and extrude the injected cement mortar, part of the cement mortar is discharged through an overflow device due to the rise of the pressure in the fracturing drill hole, and the pressure in the fracturing drill hole is kept at 3 MPa. After the cement is solidified, a cement-free fracturing space is formed at the positions of the three fracturing bags, high-pressure water is injected into the fracturing device at the pressure of 30MPa, the opening pressure of the three bag blasting valves is 10MPa, the three bag blasting valves are opened at the moment, and the high-pressure water directly acts on the coal body to break the coal body.
Example two
Referring to fig. 2 to 3, in this embodiment, a single-hole multi-stage synchronous control fracturing coal body permeability increasing method is provided, where a single-hole multi-stage synchronous control fracturing coal body permeability increasing system of the first embodiment is used, and the single-hole multi-stage synchronous control fracturing coal body permeability increasing method includes the following steps:
step 1, constructing bedding fracturing drill holes 32 in bedding of an underground working face along coal seam inclination, constructing monitoring holes 34 with the same angle as the fracturing holes at the periphery of the fracturing holes 32 according to fracturing radius, and flushing coal dust of the fracturing drill holes 32 by using underground compressed air after the drilling construction is finished; (arrangement of fracturing bore 32 and inspection hole 34 referring to FIG. 2)
step 5, adjusting the output pressure of the high-pressure pump 3 to be 5MPa, opening the water distribution box 10 to control a water distribution valve 8 of the first fracturing bag 30, starting the high-pressure pump 3, controlling water flow to be slowly injected into a high-pressure pipeline connected with the first fracturing bag 30, slowly expanding the first fracturing bag 30, extruding slurry inside the fracturing drill hole 32 due to expansion of the first fracturing bag 30 to increase the pressure inside the fracturing drill hole 32, wherein the pressure exceeds the set pressure of the overflow valve 14 by 3MPa, and cement mortar flows out of an overflow outlet 33 of the overflow valve 14 to ensure that the pressure inside the fracturing drill hole 32 is 3 MPa; closing a diversion valve 8 of the path after a high-pressure gauge 9 on a diversion box 10 corresponding to the first fracturing bag 30 reaches 5MPa and keeps injecting for 5min continuously;
step 6, according to the mode provided in the step 5, sequentially boosting the pressure of the high-pressure gauge 9 on the water distribution box 10 corresponding to the second fracturing bag 29 and the third fracturing bag 28 to 5MPa and keeping the pressure for continuous injection for 5min, then closing the high-pressure pump 3, closing the water distribution valves 8 of each path, and closing the ball valve 19; then, the overflow valve 14 and the grouting pump 16 are removed and cleaned; keeping the pressure in the fracturing drill hole 32 at 3MPa, standing for 48 hours, and completely solidifying cement mortar in the fracturing drill hole 32;
step 7, after cement mortar in the fracturing drill hole 32 is completely solidified, forming a non-cement mortar fracturing space at the positions of the first fracturing bag 30, the second fracturing bag 29 and the third fracturing bag 28, adjusting the injection pressure of the high-pressure pump 3 to be 30MPa, wherein the pressure is far greater than the explosion pressure of the fracturing bag explosion valve 31 by 10MPa, opening each water distribution valve 8 in the water distribution box, starting the high-pressure pump 3, simultaneously injecting high-pressure water into the first fracturing bag 30, the second fracturing bag 29 and the third fracturing bag 28, opening each fracturing bag explosion valve 31 along with the rise of the pressure, directly acting the high-pressure water on coal bodies at the positions of the first fracturing bag 30, the second fracturing bag 29 and the third fracturing bag 28, and starting crack initiation and continuous expansion of cracks when the high-pressure water pressure reaches a coal body crack initiation condition;
step 8, after a fracture formed by one of the first fracturing bag 30, the second fracturing bag 29 and the third fracturing bag 28 is communicated with the monitoring hole 34, the high-pressure gauge 9 on the water diversion box 10 corresponding to the fracturing bag shows that the pressure drops to a large extent (drops by more than 10MPa, and does not rise pressure after dropping), and at the moment, the water diversion valve 8 corresponding to the high-pressure gauge 9 with the pressure dropping in the water diversion box 10 is closed; the other two fracturing bags continue to fracture until fracturing fractures formed at all the fracturing bags are communicated with the monitoring holes, and then the fracturing process is finished; closing the high-pressure pump 3, opening a pressure relief valve 6 in the water distribution box 10, and releasing high-pressure water at the fracturing bag in the fracturing drill hole 32 through a pressure relief outlet 5;
and 9, after the step 8 is finished, the fracturing drill hole 32 and the monitoring hole 34 can be connected to an extraction pipeline for extraction. Because the coal body can form a plurality of main cracks after fracturing, the cracks are relatively developed, and the coal body extraction efficiency can be effectively improved.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.
Claims (10)
1. The single-hole multi-section synchronous control fracturing coal body permeability increasing system is characterized by comprising a water diversion fracturing device, a grouting device, a ball valve, a T-shaped three-way valve and an overflow device;
the water diversion fracturing device comprises a liquid storage tank, a liquid conveying pipe, a high-pressure pump, a high-pressure rubber pipe, a water diversion tank, a high-pressure water inlet rubber pipe, a plugging flange plate, a high-pressure water injection seamless steel pipe, a third fracturing bag, a second fracturing bag and a first fracturing bag; the liquid storage tank is connected with the high-pressure pump through a liquid conveying pipe, the water distribution tank is provided with a high-pressure water inlet and three high-pressure water distribution interfaces, and each high-pressure water distribution interface is independently provided with a high-pressure gauge and a water distribution valve; the high-pressure pump is connected with a high-pressure water inlet of the water distribution box through a high-pressure rubber pipe; the plugging flange plate is provided with three water inlet interfaces and one grouting port interface, and one end of each water inlet interface is connected with the three high-pressure water distribution interfaces of the water distribution box through a high-pressure water inlet rubber pipe; the other end of the three-way water inlet interface is respectively connected with three-way water inlets of the third fracturing bag through a high-pressure water injection seamless steel pipe and a high-pressure water injection pipe joint, two water inlets of the three-way water inlets of the third fracturing bag are respectively connected with two water inlets of the second fracturing bag through a high-pressure water injection seamless steel pipe and a high-pressure water injection pipe joint, and one water inlet of the two water inlets of the second fracturing bag is respectively connected with one water inlet of the first fracturing bag through a high-pressure water injection seamless steel pipe and a high-pressure water injection pipe joint;
one end of a grouting opening interface on the plugging flange plate is connected with the ball valve through a high-pressure rubber pipe, the ball valve is connected with an A interface of the T-shaped three-way valve through the high-pressure rubber pipe, a B interface of the T-shaped three-way valve is connected with the grouting device through the high-pressure rubber pipe, the grouting device is used for injecting cement mortar into a fracturing drill hole, and a C interface of the T-shaped three-way valve is connected with the overflow device through the high-pressure rubber pipe.
2. The single-hole multi-section synchronous control fracturing coal body permeability increasing system of claim 1, wherein a hole sealing sleeve is further welded and fixed on the sealing flange plate and used for sealing a fracturing drill hole.
3. The single-hole multi-section synchronous control fracturing coal body permeability increasing system of claim 1, wherein fracturing bag bursting valves are respectively arranged on the third fracturing bag, the second fracturing bag and the first fracturing bag.
4. The single-hole multi-section synchronous control fracturing coal body permeability increasing system of claim 1, wherein the distance between the first fracturing bag, the second fracturing bag and the third fracturing bag is twice of a fracturing radius, and the distance between the third fracturing bag and the three-way water inlet interface is larger than the width of a roadway loosening ring.
5. The single-hole multi-section synchronous control fracturing coal body permeability increasing system of claim 3, wherein the fracturing bag burst valve has a burst pressure of 10 MPa.
6. The single-hole multi-section synchronous control fracturing coal body permeability increasing system of claim 1, wherein the water distribution box is further provided with a pressure relief valve and a pressure relief outlet for discharging high-pressure water at a fracturing bag in a fracturing borehole through the pressure relief outlet.
7. The single-hole multi-section synchronous control fracturing coal body permeability increasing system of claim 1, wherein the grouting device comprises a grouting pump, a grouting pump pressure gauge, a grouting pressure regulating valve and a grouting pipe, the grouting pump is provided with the grouting pump pressure gauge and the grouting pressure regulating valve, a B interface of the T-shaped three-way valve is connected with a slurry outlet of the grouting pump through a rubber pipe, and the grouting pipe is connected with the other end of one grouting port interface on the plugging flange plate and extends into the fracturing drill hole.
8. The single-hole multi-section synchronous control fracturing coal body permeability increasing system according to claim 1, wherein the overflow device comprises an overflow valve, an overflow regulating valve and an overflow valve pressure gauge, an inlet of the overflow valve is connected with a C connector of the T-shaped three-way valve through a high-pressure rubber pipe, the overflow valve is provided with the overflow regulating valve and the overflow valve pressure gauge, the overflow regulating valve is used for regulating overflow pressure, and the overflow pressure gauge (13) is used for detecting fluid pressure at an inlet of the overflow valve in real time.
9. The single-hole multi-section synchronous control fracturing coal body permeability increasing method uses the single-hole multi-section synchronous control fracturing coal body permeability increasing system of any one of claims 1 to 8, and comprises the following steps:
step 1, constructing bedding fracturing drill holes along the coal seam trend in a bedding way of an underground working face, constructing monitoring holes with the same angle as the fracturing holes at the periphery of the fracturing holes according to the fracturing radius, and flushing coal scraps of the fracturing drill holes by utilizing underground compressed air after the drilling construction is finished;
step 2, feeding a first fracturing bag, a second fracturing bag and a third fracturing bag of the water diversion fracturing device into a fracturing drill hole by using a drilling machine, pushing the drilling machine into the fracturing drill hole after a grouting port interface of a plugging flange plate is connected with a grouting pipe, plugging a gap between a hole sealing sleeve and the wall of the fracturing drill hole by using the drilling machine, plugging the gap after the polyurethane expands, and fixing the plugging flange plate and a coal wall anchor net by using an iron wire;
step 3, setting the injection pressure of a grouting pump to be 3MPa by using a grouting pressure regulating valve, rotating a T-shaped three-way valve to enable an interface A of the T-shaped three-way valve to be communicated with an interface B, opening a ball valve, starting the grouting pump, injecting cement mortar into the fracturing drill hole with pressure until the pressure in the fracturing drill hole reaches 3MPa, closing the grouting pump, and stopping injection;
step 4, setting the overflow pressure to be 3MPa by using an overflow regulating valve of the overflow valve, rotating the T-shaped three-way valve to enable the interface A of the T-shaped three-way valve to be communicated with the interface C, wherein the pressure in the fracturing drill hole is the same as the overflow pressure set by the overflow valve, the overflow outlet of the overflow valve is in a closed state, and the suppressed pressure in the fracturing drill hole is still 3 MPa;
step 5, adjusting the output pressure of a high-pressure pump to be 5MPa, opening a water distribution valve of a water distribution box to control a first fracturing bag, starting the high-pressure pump, controlling the water flow to be slowly injected into a high-pressure pipeline connected with the first fracturing bag, slowly expanding the first fracturing bag, extruding slurry inside a fracturing drill hole due to expansion of the first fracturing bag to increase the pressure inside the fracturing drill hole, wherein the pressure exceeds the set pressure of an overflow valve by 3MPa, and cement mortar flows out of an overflow outlet of the overflow valve to ensure that the pressure inside the fracturing drill hole is 3 MPa; closing a shunt valve of the way after a high-pressure gauge on a shunt box corresponding to the first fracturing bag reaches 5MPa and keeps injecting for 5 min;
step 6, according to the mode provided in the step 5, sequentially boosting the pressure of high-pressure gauges on the water distribution boxes corresponding to the second fracturing bag and the third fracturing bag to 5MPa and keeping continuous injection for 5min, then closing the high-pressure pumps, closing the water distribution valves of all paths, and closing the ball valves; then, the overflow valve and the grouting pump are removed and cleaned; keeping the pressure in the fracturing drill hole at 3MPa, standing for 48 hours, and completely solidifying cement mortar in the fracturing drill hole;
step 7, after cement mortar in the fracturing drill hole is completely solidified, forming non-cement mortar fracturing spaces at the positions of the first fracturing bag, the second fracturing bag and the third fracturing bag, adjusting the injection pressure of the high-pressure pump to be 30MPa again, wherein the pressure is far greater than the blasting pressure of a blasting valve of the fracturing bag by 10MPa, opening each water diversion valve in the water diversion box, starting the high-pressure pump, simultaneously injecting high-pressure water into the first fracturing bag, the second fracturing bag and the third fracturing bag, opening each blasting valve of the fracturing bag along with the rise of the pressure, directly acting the high-pressure water on coal at the positions of the first fracturing bag, the second fracturing bag and the third fracturing bag, and starting cracking and continuously expanding cracks when the high-pressure water pressure reaches the cracking condition of the coal;
step 8, after a crack formed by one of the first fracturing bag, the second fracturing bag and the third fracturing bag is communicated with the monitoring hole, a high-pressure gauge on a water distribution box corresponding to the fracturing bag can display that the pressure drops greatly, and at the moment, a water distribution valve corresponding to the high-pressure gauge with the pressure dropping in the water distribution box is closed; the other two fracturing bags continue to fracture until fracturing fractures formed at all the fracturing bags are communicated with the monitoring holes, and the fracturing process is finished; and closing the high-pressure pump, opening a pressure relief valve in the water distribution box, and releasing high-pressure water at the fracturing bag in the fracturing drill hole through a pressure relief outlet.
10. The single-hole multi-section synchronous control fracturing coal body permeability increasing method of claim 9, characterized by further comprising:
and 9, after the step 8 is finished, the fracturing drill hole and the monitoring hole can be connected to an extraction pipeline for extraction.
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