RU2704997C1 - Method and device for control of coal bed upper part collapse area due to application of technology of pulsed hydraulic fracturing of a formation - Google Patents

Method and device for control of coal bed upper part collapse area due to application of technology of pulsed hydraulic fracturing of a formation Download PDF

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RU2704997C1
RU2704997C1 RU2019126284A RU2019126284A RU2704997C1 RU 2704997 C1 RU2704997 C1 RU 2704997C1 RU 2019126284 A RU2019126284 A RU 2019126284A RU 2019126284 A RU2019126284 A RU 2019126284A RU 2704997 C1 RU2704997 C1 RU 2704997C1
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hydraulic fracturing
pressure
pump
hydraulic
hose
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RU2019126284A
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Russian (ru)
Inventor
Бинсян ХУАН
Синлун ЧЖАО
Шулян ЧЭНЬ
Луин ШАО
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Китайский Университет Горного Дела И Технологии
Сюйчжоу Узуре Майнинг Технолоджи Ко., Лтд
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Priority to CN201810398499.4A priority patent/CN108678747B/en
Application filed by Китайский Университет Горного Дела И Технологии, Сюйчжоу Узуре Майнинг Технолоджи Ко., Лтд filed Critical Китайский Университет Горного Дела И Технологии
Priority to PCT/CN2018/113600 priority patent/WO2019205558A1/en
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    • EFIXED CONSTRUCTIONS
    • E21EARTH DRILLING; MINING
    • E21CMINING OR QUARRYING
    • E21C45/00Methods of hydraulic mining; Hydraulic monitors
    • E21C45/02Means for generating pulsating fluid jets
    • E21C45/04Means for generating pulsating fluid jets by use of highly pressurised liquid
    • EFIXED CONSTRUCTIONS
    • E21EARTH DRILLING; MINING
    • E21CMINING OR QUARRYING
    • E21C41/00Methods of underground or surface mining; Layouts therefor
    • E21C41/16Methods of underground mining; Layouts therefor
    • E21C41/18Methods of underground mining; Layouts therefor for brown or hard coal

Abstract

FIELD: mining.SUBSTANCE: invention relates to a method of controlling a section of a coal bed upper part collapse, in particular to a method and apparatus for controlling a collapsing area of an upper portion of a coal bed by applying a technology of pulsed hydraulic fracturing of a formation, which relate to the field of coal production technology application. Device in the present invention consists of a pulse pump with low feed and a common pump with high feed, which are controlled by means of a three-pass hydraulic distributor and a switching valve. First, a pump pulse path is connected in the structure, the pipeline of a high-pressure conventional pump is closed, the pulse channel closes after the end of the pulse fracture and an ordinary fracture channel opens. Method combines advantages of using methods of pulse and traditional hydraulic fracturing. First, formation of a network of cracks takes place in an array of coal by means of pulsed hydraulic fracturing of the formation. Further, using the method of traditional hydraulic fracturing of the high-movement formation, network of cracks continues to expand, structure of coal massif is sufficiently transformed, fragmentation of upper part of coal bed is reduced, and ability to collapse of this part of coal bed is increased.EFFECT: using this method and device, in the upper part of the coal bed there can be formed a sufficient number of cracks, the upper part of the coal bed can be weakened, and also the ability to collapse the upper part of the coal bed and its crushing, design is convenient, adequate level of safety and reliability is achieved, and unproductive use of resources can be reduced.9 cl, 7 dwg

Description

FIELD OF THE INVENTION
[0001] The present invention relates to a method for controlling a collapse section of an upper part of a coal seam, and in particular, to a method and apparatus for controlling a collapse section of an upper part of a coal seam by applying a pulsed hydraulic fracturing technique that relates to the field of application of coal mining technology.
DESCRIPTION OF THE PRIOR ART
[0002] Reserves and development of powerful and very powerful coal seams in China account for 40% or more of the total coal reserves and the general level of development. The fully mechanized collapse of the upper part of the coal seam is a highly productive and highly efficient way of developing coal, used to develop powerful coal seams, which is rapidly developing in China. Currently, fully mechanized caving technology has become the main way to extract coal from powerful and very powerful coal seams. The main requirements for fully mechanized mining of mines are "completion before support and breaking up into parts after support." Due to technical limitations in the mine, pressure on dense and very dense coal seams or on the overburden of the upper part of the coal seam on the working surface of the collapse of the mine decreases. This pressure cannot ensure timely and sufficient crushing of the upper part of the coal seam. Thus, the requirement for mechanized collapse of the upper part of the coal seam is not fulfilled, which leads to a low ejection speed of the upper part of the coal seam.
[0003] Traditional methods for managing the collapse section of the upper part of the coal seam include the technology of conducting preliminary drilling and blasting operations using the deep well method, the technology of hydraulic fracturing of the coal seam with water injection into it, and the combined pre-integrated technology of weakening the coal seam during explosive water injection. With respect to hard coal seams and high power seams, three methods of crushing the upper part of the coal seam have the following problems:
[0004] The technology for conducting preliminary drilling and blasting operations using the deep well method and the combined pre-integrated technology for weakening the coal seam during explosive injection of water provide for the ability to handle explosives and detonators, as well as their transportation. The “three-level control system after blasting” and the “three-person blasting system” are strictly followed when blasting. Security management is a complex process. A large amount of harmful gas, such as CO, which instantly forms as a result of large-scale blasting operations, negatively affects the process of managing mine ventilation safety. For a high-calorie gas field, exploding core charges for a fragmented coal mass cannot be used due to the latent danger of a gas explosion that could occur by a spark. The length of the treatment complex-mechanized face is usually 200 m, blasting using the deep well method is carried out in the upper and lower directions; the radiation that comes from the well must spread over the entire area; wells are long, therefore, for carrying out blasting operations a large number of pyrotechnic means, such as gunpowder and detonators, are required, while the cost of such work remains high. For blasting using explosives, densely spaced wells are usually located in a certain range, so the control range for one well is quite small.
[0005] In accordance with the technology of hydraulic fracturing of a coal seam, given the fact that the injection pressure of water into the coal seam is usually approximately 5 MP, the direction of expansion of cracks caused by hydraulic fracturing is regulated by a three-dimensional stress field, and the generated cracks are few and rarefied, the degree the weakening of the strength of the coal mass is limited. Therefore, a sufficient number of cracks cannot be formed, therefore, the effect of crushing the upper part of the coal seam is not obvious.
SUMMARY OF THE INVENTION
[0006] To address the above disadvantages of the prior art, the present invention provides a method and apparatus for controlling a collapse section of an upper part of a coal seam by applying a technology of pulsed hydraulic fracturing, which can create enough cracks in the upper part of a coal seam, weakening it, increasing the ability to collapse of this part of the coal seam and reduce its crushing. The method is convenient in design, safe and reliable, and also reduces the unproductive use of resources.
[0007] To solve the above problems, the present invention proposes a device for controlling the area of the collapse of the upper part of the coal seam due to the use of pulsed hydraulic fracturing technology, which includes a pump unit for hydraulic fracturing, a high pressure hose, a packer and a high pressure seal mounting rod . The end of the mounting rod of the high pressure seal, which reaches the bottom of the well, is equipped with a packer. The other end of the mounting rod of the high pressure seal is connected to the pump unit for hydraulic fracturing using a high pressure hose. The packer is connected to the hand pump through a thin high pressure hose. The pump unit for hydraulic fracturing consists of a high pressure pump and a pulse pump for hydraulic fracturing. The high pressure hose coming from the high pressure pump for hydraulic fracturing and the high pressure hose coming from the pulse pump for hydraulic fracturing are connected using a three-way valve. The pipeline between the high pressure pump for hydraulic fracturing and the three-way valve is equipped with switching valve I. The pipeline between the pulse pump for hydraulic fracturing and the three-way valve is equipped with switching valve II. The other end of the three-way valve is connected to the mounting rod of the high pressure seal using a high pressure hose. The high pressure hose is connected to the mounting rod of the high pressure seal through an adapter.
[0008] In addition, the high pressure hose pipe between the three-way valve and the adapter is equipped with a pressure relief valve.
[0009] At the same time, the pipeline for the high pressure hose between the three-way valve and the pressure relief valve is equipped with a device for measuring and monitoring hydraulic fracturing.
[0010] The method for controlling the collapse section of the upper part of the coal seam by applying a pulsed hydraulic fracturing includes the following steps:
[0011] step 1. Construct oriented long wells parallel to each other and perpendicular to the coal wall in a cut coal seam, also to construct inclined long wells I and inclined long wells II parallel to each other and perpendicular to the coal wall, in a transport dredging drift and a ventilation dredging drift, respectively, the wells of two excavation drifts are staggered;
[0012] step 2. Install and debug the pulse pump for hydraulic fracturing;
[0013] step 3. Place the packer on the bottom of the well, sequentially connect the high pressure seal mounting rod, adapter and high pressure hose, and connect the high pressure hose to the pulse pump for hydraulic fracturing;
[0014] step 4. Pump high-pressure water into the packer using a hand pump so that the packer expands to seal the hole;
[0015] step 5. Open switching valve II, start the pulse pump for hydraulic pulse fracturing, and in real time monitor the change in water pressure in the fractured wells and water seeping into the coal wall of the fracture zone, observing a device for measuring and monitoring hydraulic fracturing installed in the pipeline during the bursting process;
[0016] step 6. If the device for measuring and monitoring hydraulic fracturing shows that the water pressure in the well with cracks is less than 5 MPa or the duration of “fogging” of the coal formation exceeds 5-7 minutes, then you need to close the pulse pump for hydraulic fracturing , open the valve to relieve pressure, install the packer in a predetermined second rupture position for re-sealing and repeat this step until the entire drilling section is destroyed; as well as
[0017] step 7. Remove the packer, install the packer on the next well, and repeat steps cf until all wells are destroyed.
[0018] Since crushing of the upper part of the coal seam is a characteristic feature that reflects the ability to collapse a portion of the upper part of the coal seam, which is controlled mainly by two key factors: the physical and mechanical properties of the upper part of the coal seam and stress caused by mining operations, that is, pressure in mine. Pulsed hydraulic fracturing is used to control the ability to collapse a section of the upper part of a coal seam according to the principle that high-pressure water is pumped periodically into the wells of a coal seam by a high-pressure pulse pump, so that the walls of the well undergo multiple cracking during periodic fatigue loading thereby generating more cracks outside the control of the three-dimensional stress field. In addition, a high-frequency shock wave can activate natural cracks in the coal seam to cause them to re-expand and propagate through them, thus forming a complex network of cracks in the coal seam, completely cutting the coal mass and weakening its general physical and mechanical properties. Meanwhile, the permeability of the coal mass can also be changed, as a result of which the coal mass can be moistened by complete absorption of water and its further softening. Thus, the control technology of pulsed hydraulic fracturing of hard coal relates to: using the method of pulsed hydraulic fracturing for preliminary destruction of macro- and microstructures of its upper part, weakening the strength of the coal mass by fracturing and softening, and thus satisfy the requirement to increase the ability to the collapse of this part of the coal seam depending on the destructibility of coal at mine pressure.
[0019] As a further improvement of the present invention, based on pulsed hydraulic fracturing and weakening of the coal seam, in combination with the advantages of pulsed hydraulic fracturing and conventional hydraulic fracturing, the technology is used to weaken the upper part of the coal seam by “pulsed hydraulic fracturing”, after which is supposed to be a traditional hydraulic fracturing.
[0020] Based on the above method, a high pressure pump for hydraulic fracturing is mounted and debugged in step 2, both a pulse pump for hydraulic fracturing and a pulse pump for hydraulic fracturing and a high pressure pump for hydraulic fracturing are connected in parallel together via a three-way valve.
[0021] In step 5, after the pulse pump for hydraulic fracturing is activated to conduct the pulse hydraulic fracture for 30 minutes, the pulse pump for hydraulic fracture and the switching valve II are closed, then the switching valve I and the high pressure pump for hydraulic fracturing they open, a crack forms during a pulsed hydraulic fracture, then continues to expand by pumping with a high feed rate, thereby increasing the propagation distance of the crack .
[0022] In step 6, if the device for measuring and monitoring hydraulic fracturing shows that the water pressure in the well with cracks is less than 5 MPa or the duration of “fogging” of the coal formation exceeds 5-7 minutes, then the high pressure pump for hydraulic fracturing is closed formation, the pressure relief valve opens, the packer is installed in a given second position of the gap for re-sealing and this step is repeated until the entire drilling section is destroyed.
[0023] An improved method includes: firstly injecting continuously supplied high pressure pulsed water into the coal seam by means of a high pressure pulsed pump and repeatedly applying periodic high pressure to the coal seam to create multiple cracks in the coal seam; and then, using traditional hydraulic fracturing with great progress, to expand the further spread of the network of fractures generated by a pulsed hydraulic fracturing, so that through fractures between adjacent wells propagate, the coal mass is divided into masses of a certain size and shape, the coal structure is completely transformed, integrity the coal seam is destroyed, the strength of the coal mass is reduced, and the general physical and mechanical properties of the coal seam are weakened, thereby making it more fragmented during the ejection of the working surface, reducing fragmentation of the upper part of the coal seam and increasing the ability to collapse this part of the coal seam.
[0024] In addition, in step 1, non-rechargeable wells are first constructed, and then wells with two recessed drifts are constructed, and the drifts are drilled sequentially from the recess direction to the direction of the main drift; and the hydraulic fracturing sequence in steps 3 to 6 is the same as the well construction sequence, hydraulic fracturing and well construction are performed simultaneously and carried out in parallel, and if the construction speed is consistent, the wells can be built ahead of schedule.
[0025] Also, in order to provide the effect of fracture of long wells and to increase the uniformity of fractures and their number, a segmented return fracture is used in the process of hydraulic fracturing, the length of the segmented fracture is from 10 to 20 m, and the steps in particular are:
[0026] (a) starting a pulse pump for hydraulic fracturing or a high pressure pump for hydraulic fracturing;
[0027] (b) pumping water into one fractured well for cyclic hydraulic fracturing;
[0028] (c) if the device for measuring and monitoring hydraulic fracturing shows that the water pressure in the well with cracks is less than 5 MPa or the duration of “fogging” of the coal formation exceeds 5-7 minutes, then the pulse pump for hydraulic fracturing is closed or high pressure pump for hydraulic fracturing and a valve is opened to relieve pressure to complete cyclic hydraulic fracturing;
[0029] (d) then, retreating from the packer by a distance of 10 to 20 m in the direction of the wellhead, a cyclic hydraulic fracturing is performed again;
[0030] (e) the action is repeated until the packer retreats to a depth of 15 m from the borehole with cracks for the last cyclic hydraulic fracturing; as well as
[0031] (f) removing the packer to complete the return segmented hydraulic fracture.
[0032] In addition, a high pressure pump for hydraulic fracturing produces a pressure range of 0 to 20 MPa and a nominal flow rate of 6.7 m 3 / h.
[0033] The packer includes a front expansion hose seal and a rear expansion hose seal. The seal of the front expansion hole of the hose and the seal of the rear expansion hole of the hose are located in the well at a distance from each other. A connecting pipe and a thin high-pressure pump are located between the front and rear hose extensions. The front hose hole seal includes a first quick-acting hydraulic connector, a first fixed sleeve, a first sliding sleeve, a first metal pipe and a first hole seal recess. One end of the first metal pipe passes through the first sliding sleeve and is connected to the first quick-acting hydraulic connector, and the other end passes through the first sliding sleeve. The rear hose opening seal includes a second quick-acting hydraulic connector, a third quick-acting hydraulic connector, a threaded connector, a second sliding sleeve, a second fixed sleeve, a second metal pipe, and a second hole seal recess. One end of the second metal pipe passes through the second sliding sleeve and is connected to the second quick-acting hydraulic connector, and the other end is connected to the second sliding sleeve. The first high-speed hydraulic connector is connected to the second high-speed hydraulic connector using a connecting pipe. One end of a thin high-pressure hose passes through the first stationary sleeve and is connected to the front expansion hole seal of the hose, and the other end sequentially passes through the second fixed sleeve, the second depression of the hole seal, the second sliding sleeve and the threaded connector and is connected to an external hand pump. When the hand pump is pressed, the capsule bore seal expands in the radial direction and retracts in the longitudinal direction, and the first sliding sleeve and the second sliding sleeve freely slide along the first metal pipe and the second metal pipe, respectively. The connecting pipe is provided with a through hole for discharging high pressure water to destroy the coal.
[0034] Compared with traditional blasting techniques for attenuating the upper part of the coal seam and traditional hydraulic fracturing techniques for attenuating the formation, the pulsed hydraulic fracturing technology for attenuating the upper part of the reservoir adopted in the present invention has the following beneficial effects:
[0035] 1. A greater number of hydraulic fractures in the coal seam can be generated by pulsed hydraulic fracturing, while primary cracks in the coal seam are activated and a complex network of cracks is formed in the coal seam to cut through the coal mass, thereby completely weakening the coal the upper part of the coal seam, increasing the ability to collapse this part of the coal seam and reducing its fragmentation.
[0036] 2. A segmented pulsed hydraulic return fracture is used, which improves the uniformity of cracks in the coal mass and their number to help improve the overall ability to fragment fragmentation of the collapse of the upper part of the coal seam.
[0037] 3. The holes are sealed with a hydraulic fracture packer. Compared to traditional hydraulic fracturing with a single-layer bore seal, a two-layer packer can seal high-pressure water between two capsule bore seals to achieve segmented fracturing of one well, thereby significantly reducing the likelihood of punching and improving the stability of the hydraulic fracturing process.
[0038] 4. The method of controlling the collapse section of the upper part of the coal seam due to the use of pulsed hydraulic fracturing technology is easy to use, convenient for construction, safe and reliable, and also helps to increase the rate of collapse of the upper part of the coal seam on a fully mechanized collapse surface and reduces unproductive use of resources, and has wide practical application.
BRIEF DESCRIPTION OF THE DRAWINGS
[0039] FIGURE 1 is a device and a view of the structure in accordance with the first embodiment of the present invention;
[0040] FIGURE 2 is a device and a construction view in accordance with a second embodiment of the present invention;
[0041] FIGURE 3 is a depiction of a method for constructing a well in accordance with the present invention;
[0042] FIGURE 4 is a sectional view taken along line 1-1 of FIGURE 3;
[0043] FIGURE 5 is a sectional view taken along line 2-2 of FIGURE. 3;
[0044] FIGURE 6 is a sectional view taken along line 3-3 of FIGURE 3; as well as
[0045] FIGURE 7 is a schematic view of the design of a packer.
[0046] In the figures: 1: Transport excavation drift; 2: Coal seam; 3: Roofing; 4: Inclined long well I; 5: Mounting rod of high pressure seal; 6: packer; 6-1: Seal for the front expansion hole of the hose; 6-2: Seal for the back expansion hole of the hose; 6-3: connecting pipe; 6-4: First high-speed hydraulic connector; 6-5: First stationary sleeve; 6-6: First sliding sleeve; 6-7: First metal pipe; 6-8: Second high-speed hydraulic connector; 6-9: Third high-speed hydraulic connector; 6-10: Second stationary sleeve; 6-11: Second metal pipe; 6-13: Second sliding sleeve; 6-14: First recess of the hole seal; 6-15: Second recess of the hole seal; 6-16: Threaded connector; 7: pump unit hydraulic fracturing; 7-1: Pulse pump for hydraulic fracturing; 7-2: High pressure pump for hydraulic fracturing; 8: high pressure hose; 9: Pressure relief valve; 10: Instrument for measuring and monitoring hydraulic fracturing; 11: Section of a coal seam; 12: Vent extracting drift; 13: Changeover valve II; 14: Changeover valve I; 15: Three-way directional control valve; 16: adapter; 17: Thin high-pressure hose; 18: hand pump; 19: Oriented long well; and 20: Inclined Long Well II.
DETAILED DESCRIPTION OF THE INVENTION
[0047] The present invention is described in more detail below with reference to the accompanying drawings.
[0048] First Embodiment
[0049] As shown in FIG. 1 and FIG. 3-6, the average thickness of the coal seam of the mine is 7.5 m; direct roof of coarse-grained sandstone covered with fine pebbles, in some places clay shale and sand shale, an average thickness of 6.32 m; the upper roof is made of coarse-grained sandstone, with an average thickness of 4.06 m; and a direct bottom of fine-grained sandstone with an average thickness of 2.10 m. Cutting of the working surface: guy line, net and cable are combined to support a rectangular drift with a net width of 8.5 m, a net height of 3.2 m and a cross-sectional area of 27.2 m 2 . Transport excavation drift of the working surface: guy, network and cable are combined to support a rectangular drift with a network width of 4.6 m, a network height of 3.2 m and a cross-sectional area of 14.72 m 2 . Venting dredging drift of the working surface: the support option is the same as for the transport dredging drift, the rectangular drift is also 4.6 m wide, 3.2 m high and a cross-sectional area of 14.72 m 2 .
[0050] As shown in FIG. 3 and FIG. 4, oriented long wells 19, parallel to each other and perpendicular to the coal wall, are constructed in a section of the coal seam, the hole start point is 1.2 m from the bottom, the hole end point is 1 m from the roof, and the wells are 50 m and a diameter of 75 mm.
[0051] As shown in FIG. 3 and FIG. 5, inclined long wells 14 parallel to each other and perpendicular to the coal wall, built in a transport excavation drift, the hole start point is 1.2 m from the bottom, the hole end point is 1 m from the roof, and the wells are 105 m and a diameter of 75 mm.
[0052] As shown in FIG. 3 and FIG. 6, inclined long wells 1120, parallel to each other and perpendicular to the coal wall, are constructed by a ventilation excavation drift, the place where the hole starts is 1.2 m from the bottom, the place where the hole ends is 1 m from the roof, the wells are 105 m long and the diameter is 75 mm, and the wells of two excavating drifts are staggered. When placing wells, geological structural zones, such as faults, should be avoided, as far as possible in accordance with geological data, and the influence of geological structures on the fracture effect of the upper part of the coal seam should be avoided.
[0053] First, non-rechargeable wells are constructed, and then wells of two extraction drifts are constructed, and drilling of two extraction drifts is performed sequentially from the cut direction to the direction of the main drift. The sequence of hydraulic fracturing is the same as the sequence of well construction, hydraulic fracturing and well construction are carried out simultaneously and are carried out in parallel, and if the construction speed is consistent, then the wells can be built ahead of schedule.
[0054] To ensure the effect of cracking of long wells and to increase the uniformity of cracks and their number, a segmented return fracture is used, a special packer is used to seal the holes, the segmented fracture length is from 10 to 20 m and is determined after several tests in accordance with the situation on site.
[0055] The steps are as follows:
[0056] As shown in FIG. 3, in step 1, the oriented long wells 19 parallel to each other and perpendicular to the coal wall in the cut coal seam 11, and the inclined long wells I 14 and the inclined long wells II 1120, parallel to each other and perpendicular to the coal wall, were constructed in the transport excavation drift 1 and a venting excavation drift 20, respectively, the wells of two extraction drifts are staggered.
[0057] As shown in FIG. 1, in step 2, a pulse pump for hydraulic fracturing 7-1 is installed and debugged.
[0058] In step 3, the packer 6 is transferred to the lower part of the well 4, well 19 or well 20, the mounting rod of the high pressure seal 5, the adapter 16 and the high pressure hose 8 are connected in series, and the high pressure hose is connected to the pulse pump for hydraulic fracturing 7 -one.
[0059] In step 4, high pressure water is pumped into the packer using hand pump 18 so that packer 6 expands to seal the hole.
[0060] In step 5, switching valve II is opened, the pulse pump 7-1 is started for hydraulic fracturing, where the pulse pump for hydraulic fracturing 7-1 generates a hydraulic pulse having a pressure of 20 MPa and a nominal flow rate of 6.7 m 3 / h; and the change in water pressure in cracked wells and water leakage into the coal wall of the crack zone is monitored in real time, observing a device for measuring and monitoring hydraulic fracturing 10 installed in the pipeline during the hydraulic fracturing process.
[0061] In step 6, if the device for measuring and monitoring hydraulic fracturing 10 shows that the water pressure in the well with cracks is less than 5 MPa or the duration of “fogging” of the coal formation exceeds 5-7 minutes, then the pulse pump for hydraulic fracturing is closed formation 7-1, the pressure relief valve 9 opens, and the packer 6 is installed in a given second position of the gap for re-sealing. The step is repeated until the entire drilling section is destroyed.
[0062] In step 7, the packer is removed and mounted on the next well. Steps 3-6 are repeated until all wells are destroyed.
[0063] The steps of the segmented return gap are in particular as follows:
[0064] (a) Start the pulse pump for hydraulic fracturing 7-1.
[0065] (b) Pump water into a single fractured well for cyclic hydraulic fracturing;
[0066] (c) Close the pulse pump for hydraulic fracturing 7-1, if the device for measuring and monitoring hydraulic fracturing 10 shows that the water pressure in the well with cracks is less than 5 MPa or the duration of “fogging” of the coal formation exceeds 5- 7 min, and open the pressure relief valve 9 to complete the cyclic hydraulic fracture;
[0067] (d) Then indent from the packer 6 10-20 m in the direction of the well bore and cycle the fracturing again.
[0068] (e) Repeat until the packer 6 retreats to a depth of 15 m from the borehole with cracks for the last cyclic hydraulic fracturing.
[0069] (f) Remove the packer 6 to complete the return segmented hydraulic fracture.
[0070] Second Embodiment
[0071] As shown in FIG. 2, FIG. 3-6, the average thickness of the coal seam of the mine is 9 meters. Direct roof of coarse-grained sandstone, covered with fine pebbles, in some places clay shale and sand shale, with an average thickness of 7 m; the upper roof is made of coarse-grained sandstone, with an average thickness of 4 m; and a direct bottom of fine-grained sandstone with an average thickness of 2 m. Cutting the working surface: guy, network and cable are combined to support a rectangular drift with a network width of 9 m, a network height of 3 m and a cross-sectional area of 27 m 2 . Transport excavation drift of the working surface: guy, network and cable are combined to support a rectangular drift with a network width of 4.6 m, a network height of 3.2 m and a cross-sectional area of 14.72 m 2 . Venting dredging drift of the working surface: the support option is the same as for the transport dredging drift, the rectangular drift is also 4.6 m wide, 3.2 m high and a cross-sectional area of 14.72 m 2 .
[0072] As shown in FIG. 3 and FIG. 4, oriented long wells 19, parallel to each other and perpendicular to the coal wall, are constructed in a section of the coal seam, the hole start point is 1.2 m from the bottom, the hole end point is 1 m from the roof, and the wells are 50 m and a diameter of 75 mm.
[0073] As shown in FIG. 3 and FIG. 5, inclined long wells 14 parallel to each other and perpendicular to the coal wall, built in a transport excavation drift, the hole start point is 1.2 m from the bottom, the hole end point is 1 m from the roof, and the wells are 105 m and a diameter of 75 mm.
[0074] As shown in FIG. 3 and FIG. 6, inclined long wells 1120, parallel to each other and perpendicular to the coal wall, are constructed by a ventilation excavation drift, the place where the hole starts is 1.2 m from the bottom, the place where the hole ends is 1 m from the roof, the wells are 105 m long and the diameter is 75 mm, and the wells of two excavating drifts are staggered. When placing wells, geological structural zones, such as faults, should be avoided, as far as possible in accordance with geological data, and the influence of geological structures on the fracture effect of the upper part of the coal seam should be avoided.
[0075] First, non-rechargeable wells are constructed, and then wells of two extraction drifts are constructed, and drilling of two extraction drifts is performed sequentially from the cut direction to the direction of the main drift. The sequence of hydraulic fracturing is the same as the sequence of well construction, hydraulic fracturing and well construction are carried out simultaneously and are carried out in parallel, and if the construction speed is consistent, then the wells can be built ahead of schedule.
[0076] To ensure the effect of cracking of long wells and to increase the uniformity of cracks and their number, a segmented return fracture is used, a special packer is used to seal the holes, the segmented fracture length is from 10 to 20 m and is determined after several tests in accordance with the situation on site.
[0077] The steps are as follows:
[0078] In step 1, oriented long wells 19 parallel to each other and perpendicular to the coal wall in the cut coal seam 11, and inclined long wells I 14 and inclined long wells II 1120, parallel to each other and perpendicular to the coal wall, are constructed in a transport excavation drift 1 and a venting excavation drift 12, respectively, the wells of two extraction drifts are staggered.
[0079] In step 2, a high pressure pump for hydraulic fracturing 7-2 is mounted and debugged, while a pulse pump for hydraulic fracturing 7-1, and a pulse pump for hydraulic fracturing 7-1 and a high pressure pump for hydraulic fracturing are installed 7-2 are connected in parallel together via a three-way valve.
[0080] In step 3, the packer 6 is transferred to the bottom of the borehole 4, the mounting rod of the high pressure seal 5, the adapter 16 and the high pressure hose 8 are connected in series, and the high pressure hose is connected to a hydraulic fracture pump 7-1 and a high pressure pump for hydraulic fracturing 7-2.
[0081] In step 4, high pressure water is pumped into the packer using hand pump 18 so that packer 6 expands to seal the hole.
[0082] In step 5, the switching valve II 13 on the pipeline of the pulse pump for hydraulic fracturing 7-1 is opened, the switching valve I 14 on the pipeline of the high pressure pump for hydraulic fracturing 7-2 is closed, the pulse pump for hydraulic fracturing 7-1 is started, gives out a hydraulic pulse having a pressure in MPa and a nominal flow rate of 12 m 3 / h.
[0083] In step 6, after the hydraulic fracturing pulse pump 7-1 is actuated to conduct hydraulic fracturing for 30 minutes, the hydraulic fracturing pulse pump 7-1 and the switching valve II 13 are closed, then the switching valve I 14 and the high-pressure pump for hydraulic fracturing 7-2 open, a crack is formed during a pulsed hydraulic fracture, then continues to expand by pumping with a high flow rate, thereby increasing the range crack propagation, and the high pressure pump for hydraulic fracturing 7-2 has an allowable pressure of 63 MPa and a nominal flow rate of 12 m 3 / h.
[0084] In step 7, if the device for measuring and monitoring hydraulic fracturing 10 shows that the water pressure in the well with cracks is less than 5 MPa or the duration of “fogging” of the coal formation exceeds 5-7 minutes, then the high pressure pump for hydraulic the fracture 7-2, the pressure relief valve 9 opens, and the packer 6 is installed in a given second position of the fracture for re-sealing. The step is repeated until the entire drilling section is destroyed.
[0085] In step 8, the packer 6 is removed and mounted on the next well. Steps 3-7 are repeated until all wells are destroyed.
[0086] The steps of the segmented return gap are in particular the following:
[0087] (a) Run a pulse pump for hydraulic fracturing 7-1 or a high pressure pump for hydraulic fracturing 7-2.
[0088] (b) Pump water into one fractured well for cyclic hydraulic fracturing;
[0089] (c) Close the pulse pump for hydraulic fracturing 7-1 or the high pressure pump 7-2 for hydraulic fracturing, if the device for measuring and monitoring hydraulic fracturing 10 indicates that the water pressure in the well with cracks is less than 5 MPa or the duration of "fogging" of the coal seam exceeds 5-7 minutes, and open the valve to relieve pressure 9 to complete the cyclic hydraulic fracture;
[0090] (d) Then indent from the packer 6 10-20 m in the direction of the well bore and cycle the fracturing again.
[0091] (e) Repeat until the packer retreats to a depth of 15 m from the cracked borehole for the last cyclic hydraulic fracturing.
[0092] (f) Remove the packer 6 to complete the return segmented hydraulic fracture.
[0093] As shown in FIG. 7, the packer includes a front expansion hole seal of the hose 6-1 and a rear expansion hole seal of the hose 6-2. The seal of the front expansion hole of the hose 6-1 and the seal of the rear expansion hole of the hose 6-2 are located in the well at a distance from each other. The connecting pipe 6-3 and the thin high-pressure pump 17 are located between the front and rear hose extension hole seals. The front hose hole seal includes a first quick-acting hydraulic connector 6-4, a first fixed sleeve 6-5, a first sliding sleeve 6-6, a first metal pipe 6-7, and a first recess of the hole seal 6-14. One end of the first metal pipe 6-7 passes through the first sliding sleeve 6-6 and is connected to the first high-speed hydraulic connector 6-4, and the other end passes through the first sliding sleeve 6-6. The rear hose opening seal includes a second high-speed hydraulic connector 6-8, a third high-speed hydraulic connector 6-9, a threaded connector 6-16, a second sliding sleeve 6-13, a second fixed sleeve 6-10, a second metal pipe 6-11 and the second recess of the seal hole 6-15. One end of the second metal pipe 6-11 passes through the second sliding sleeve 6-10 and is connected to the second quick-acting hydraulic connector 6-8, and the other end is connected to the second sliding sleeve 6-13. The first high-speed hydraulic connector 6-4 is connected to the second high-speed hydraulic connector 6-8 using a connecting pipe 6-3. One end of the thin high-pressure hose 17 passes through the first fixed sleeve 6-5 and is connected to the front expansion hole seal of the hose 6-1, and the other end passes sequentially through the second fixed sleeve 6-10, the second recess of the hole seal 6-15, the second sliding the sleeve 6-13 and the threaded connector 6-16 and is connected to the external hand pump 18. When the hand pump is pressed, the capsule hole seal expands in the radial direction and retracts in the longitudinal direction, and the first is sliding the second sleeve 6-6 and the second sliding sleeve 6-13 freely slide along the first metal pipe 6-7 and the second metal pipe 6-11, respectively. The connecting pipe 6-3 is provided with a through hole for discharging high pressure water to destroy the coal.
[0094] After completion of the well construction, the connecting pipe 6-3 of the appropriate length is selected according to the hydraulic fracture length of the structure, the hand pump 18 pumps water through a thin high-pressure hose 17 into the hole seals of the front and rear hose extensions to seal the hole seal extensions, then a pulse hydraulic fracturing pump 7-1 or high pressure hydraulic fracturing pump 7-2 pumps high pressure water into the wells through the first metal the cutting room 6-7 and the second metal pipe 6-11, and the through hole on the connecting pipe 6-3 is used to discharge water under high pressure to destroy coal. The seal of the front expansion hole of the hose 6-1 and the seal of the rear expansion hole of the hose 6-2 after the water injection expand radially and extend in the longitudinal direction, the first sliding sleeve 6-6 and the second sliding sleeve 6-13 freely slide along the first metal pipe 6-7 and a second metal pipe 6-11, respectively, between the metal pipe and the sliding sleeve, an o-ring is provided to prevent water from flowing out of the packer, and water is pumped until a well segment is found Between the two gaskets of the expansion holes of the hose, it will not be completely broken. Water pressure is relieved and two hole seals return to the state that was before the water injection, and can be moved directly to the next well for hydraulic fracturing.

Claims (25)

1. The control device for the collapse section of the upper part of the coal seam due to the use of pulsed hydraulic fracturing technology, which combines a pump unit for hydraulic fracturing (7), a high pressure hose (8), a packer (6) and a high pressure seal mounting rod (5), the end of the high-pressure seal mounting rod (5), which reaches the bottom of the well, is equipped with a packer (6), the other end of the high-pressure seal mounting rod (5) is connected to the hydraulic pump unit fracturing the formation (7) using a high pressure hose (8), the packer (6) is connected to the hand pump (18) through a thin high pressure hose (17), while the pump unit for hydraulic fracturing (7) contains a high pressure pump for hydraulic fracturing (7-2) and a pulse pump for hydraulic fracturing (7-1), a high pressure hose (8) coming from a high pressure pump for hydraulic fracturing (7-2), and a high pressure hose (8) coming from the pulse pump for hydraulic fracturing (7-1), connection using a three-way valve (15), the pipeline between the high-pressure pump for hydraulic fracture (7-2) and the three-way valve (15) is equipped with a switching valve I (14), the pipeline between the pulse pump for hydraulic fracture (7-1) and the three-way the control valve (15) is equipped with switching valve II (13), the other end of the three-way control valve (15) is connected to the mounting rod of the high pressure seal (5) using a high pressure hose (8), the high pressure hose (8) is connected to the high pressure seal (5) through the adapter (16).
2. The control device for the collapse section of the upper part of the coal seam due to the use of pulsed hydraulic fracturing technology according to claim 1, characterized in that the high pressure hose pipe between the three-way valve (15) and the adapter (16) is equipped with a pressure relief valve (9).
3. The control device for the collapse section of the upper part of the coal seam due to the use of pulsed hydraulic fracturing technology according to claim 1, characterized in that the high-pressure hose pipeline between the three-way valve (15) and the pressure relief valve (9) is equipped with a measuring and control device hydraulic fracturing (10).
4. The way to control the collapse section of the upper part of the coal seam due to the use of pulsed hydraulic fracturing technology consists of the following steps:
step 1. construction of oriented long wells (19) parallel to each other and perpendicular to the coal wall in a cut coal seam (11), and inclined long wells I (4) and inclined long wells II (20) parallel to each other and perpendicular to the coal wall , in the transport excavation drift (1) and the ventilation excavation drift (12), respectively, the wells of two extraction drifts are staggered;
step 2. installation and debugging of a pulse pump for hydraulic fracturing (7-1);
step 3. moving the packer (6) to the lower part of the well (4), connecting the mounting rod of the high pressure seal (5), the adapter (16) and the high pressure hose (8) in series, and connecting the high pressure hose to the pulse pump for hydraulic fracturing ( 7-1);
step 4. injection of high-pressure water into the packer using a hand pump (18) so that the packer (6) expands to seal the hole;
step 5. opening the switching valve II, starting the pulse pump (7-1) for hydraulic fracturing, monitoring the change in water pressure in the wells with cracks and water seeping into the coal wall of the crack zone in real time, while observing the device for measuring and monitoring hydraulic fracturing (10) installed in the pipeline during the hydraulic fracturing process;
step 6. if the device for measuring and monitoring hydraulic fracturing (10) shows that the water pressure in the well with cracks is less than 5 MPa or the duration of “fogging” of the coal formation exceeds 5-7 minutes, then the pulse pump for hydraulic fracturing is closed ( 7-1), the pressure relief valve (9) opens, and the packer (6) is installed in the specified second gap position for re-sealing, and this step is repeated until the entire drilling section is destroyed;
step 7. removing the packer (6), installing the packer on the next well, repeating steps 3-6 until all wells are destroyed.
5. The method of controlling the area of the collapse of the upper part of the coal seam due to the application of the technology of pulsed hydraulic fracturing according to claim 4, characterized in that
in step 2, a high pressure pump for hydraulic fracturing (7-2) is mounted and debugged, while a pulse pump for hydraulic fracturing (7-1), and a pulse pump for hydraulic fracturing (7-1) and a high pressure pump are installed for hydraulic fracturing (7-2) are connected in parallel together by means of a three-way valve;
in step 5, after the pulse pump for hydraulic fracturing (7-1) is actuated to conduct a pulse hydraulic fracture for 30 minutes, the pulse pump for hydraulic fracture (7-1) and switching valve II (13) are closed, then the switching valve I (14) and the high-pressure pump for hydraulic fracturing (7-2) open, a crack forms during a pulsed hydraulic fracture, then continues to expand by pumping with a high flow rate, thereby increasing the propagation distance I am cracked; as well as
in step 6, if the device for measuring and monitoring hydraulic fracturing (10) shows that the water pressure in the well with cracks is less than 5 MPa or the duration of “fogging” of the coal formation exceeds 5-7 minutes, then the high pressure pump for hydraulic fracturing is closed formation (7-2), the pressure relief valve (9) opens, the packer (6) is installed in the specified second position of the gap for re-sealing, and this step is repeated until the entire drilling section is destroyed.
6. The method of managing the collapse section of the upper part of the coal seam due to the use of pulsed hydraulic fracturing technology according to claim 4 or 5, characterized in that in step 1, first, non-rechargeable wells are built, and then wells with two recessed drifts are built, and drilling of these drifts sequentially from the direction of the recess to the direction of the main drift; and the hydraulic fracturing sequence in steps 3 to 6 is the same as the well construction sequence, hydraulic fracturing and well construction are performed simultaneously and carried out in parallel, and if the construction speed is consistent, then the wells can be built ahead of schedule.
7. The method for controlling the collapse section of the upper part of the coal seam due to the application of the pulsed hydraulic fracturing technology according to claim 6, characterized in that a segmented return fracture is used, the length of the segmented fracture is from 10 to 20 m, and the steps in particular are as follows:
(a) starting a pulse pump for hydraulic fracturing (7-1) or a high pressure pump for hydraulic fracturing (7-2);
(b) injection of water into one well with fractures for cyclic hydraulic fracturing;
(c) if the device for measuring and monitoring hydraulic fracturing (10) shows that the water pressure in the well with cracks is less than 5 MPa or the duration of “fogging” of the coal formation exceeds 5-7 minutes, then the pulse pump for hydraulic fracturing is closed ( 7-1) or a high pressure pump for hydraulic fracturing (7-2) and a valve is opened to relieve pressure (9) to complete the cyclic hydraulic fracturing;
(d) then, retreating from the packer (6) a distance of 10 to 20 m in the direction of the wellhead, a cyclic hydraulic fracturing is performed again;
(e) the action is repeated until the packer (6) retreats to a depth of 15 m from the borehole with cracks for the last cyclic hydraulic fracturing; as well as
(f) removing the packer (6) to complete the return segmented hydraulic fracture.
8. The way to control the collapse section of the upper part of the coal seam due to the application of the technology of pulsed hydraulic fracturing according to claim 7, characterized in that the high pressure pump for hydraulic fracturing (7-1) produces a pressure range from 0 to 20 MPa and a nominal flow rate 6.7 m 3 / h.
9. The method of controlling the area of the collapse of the upper part of the coal seam due to the use of pulsed hydraulic fracturing technology according to claim 8, characterized in that the packer contains a seal for the front expansion holes of the hose (6-1) and a seal for the rear expansion holes of the hose (6-2) , the seal of the front expansion hole of the hose (6-1) and the seal of the rear expansion hole of the hose (6-2) are located in the well at a distance from each other, and the connecting pipe (6-3) and the thin high-pressure pump 17 are located between the pack otnitelyami holes front and rear hose extensions; the front hose hole sealant comprises a front hose hole sealant, includes a first quick-acting hydraulic connector (6-4), a first fixed sleeve (6-5), a first sliding sleeve (6-6), a first metal pipe (6-7), and the first recess of the hole seal (6-14), one end of the first metal pipe (6-7) passes through the first sliding sleeve (6-6) and is connected to the first quick-acting hydraulic connector (6-4), and the other end passes through the first sliding sleeve (6-6); the rear hose hole seal includes a second quick-acting hydraulic connector (6-8), a third quick-acting hydraulic connector (6-9), a threaded connector (6-16), a second sliding sleeve (6-13), and a second fixed sleeve (6- 10), a second metal pipe (6-11) and a second recess of the hole seal (6-15), one end of the second metal pipe (6-11) passes through a second sliding sleeve (6-10) and is connected to a second high-speed hydraulic connector ( 6-8), and the other end is connected to the second sliding in ulkoy (6-13); the first high-speed hydraulic connector (6-4) is connected to the second high-speed hydraulic connector (6-8) using a connecting pipe (6-3), one end of a thin high-pressure hose (17) passes through the first stationary sleeve (6-5) and connected to the seal of the front expansion hole of the hose (6-1), and the other end sequentially passes through the second fixed sleeve (6-10), the second recess of the hole seal (6-15), the second sliding sleeve (6-13) and the threaded connector ( 6-16) and connected to an external hand pump at (18); when the hand pump is pressed, the capsule hole seal expands in the radial direction and retracts in the longitudinal direction, and the first sliding sleeve (6-6) and the second sliding sleeve (6-13) slide freely along the first metal pipe (6-7) and a second metal pipe (6-11), respectively; and the connecting pipe (6-3) is provided with a through hole for discharging high pressure water to destroy the coal.
RU2019126284A 2018-04-28 2018-11-02 Method and device for control of coal bed upper part collapse area due to application of technology of pulsed hydraulic fracturing of a formation RU2704997C1 (en)

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