CN111425178A - Coal mine underground branch drilling staged fracturing permeability increasing method and pressure pumping integrated device - Google Patents
Coal mine underground branch drilling staged fracturing permeability increasing method and pressure pumping integrated device Download PDFInfo
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- CN111425178A CN111425178A CN202010389926.XA CN202010389926A CN111425178A CN 111425178 A CN111425178 A CN 111425178A CN 202010389926 A CN202010389926 A CN 202010389926A CN 111425178 A CN111425178 A CN 111425178A
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- 238000005553 drilling Methods 0.000 title claims abstract description 61
- 239000003245 coal Substances 0.000 title claims abstract description 59
- 238000000034 method Methods 0.000 title claims abstract description 29
- 230000001965 increasing effect Effects 0.000 title claims abstract description 17
- 238000005086 pumping Methods 0.000 title claims abstract description 16
- 230000035699 permeability Effects 0.000 title abstract description 16
- 239000012530 fluid Substances 0.000 claims abstract description 33
- 238000010276 construction Methods 0.000 claims abstract description 27
- 238000000605 extraction Methods 0.000 claims abstract description 23
- 239000012266 salt solution Substances 0.000 claims abstract description 18
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 claims abstract description 7
- 230000005484 gravity Effects 0.000 claims abstract description 5
- 239000000463 material Substances 0.000 claims abstract description 5
- 239000011347 resin Substances 0.000 claims abstract description 5
- 229920005989 resin Polymers 0.000 claims abstract description 5
- 238000007789 sealing Methods 0.000 claims description 38
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 20
- 238000002347 injection Methods 0.000 claims description 9
- 239000007924 injection Substances 0.000 claims description 9
- 239000011435 rock Substances 0.000 claims description 9
- 238000009826 distribution Methods 0.000 claims description 6
- 239000004576 sand Substances 0.000 claims description 6
- 238000012360 testing method Methods 0.000 claims description 6
- 238000005065 mining Methods 0.000 claims description 4
- 238000012856 packing Methods 0.000 claims description 4
- 238000002360 preparation method Methods 0.000 claims description 4
- 238000006073 displacement reaction Methods 0.000 claims description 3
- 230000000149 penetrating effect Effects 0.000 claims description 3
- 239000013049 sediment Substances 0.000 claims description 3
- 238000012795 verification Methods 0.000 claims description 3
- 238000005406 washing Methods 0.000 claims description 3
- 238000002637 fluid replacement therapy Methods 0.000 claims description 2
- 230000009977 dual effect Effects 0.000 claims 1
- 239000007788 liquid Substances 0.000 abstract description 2
- 238000005516 engineering process Methods 0.000 description 7
- 230000000694 effects Effects 0.000 description 6
- 238000011161 development Methods 0.000 description 4
- 229910000861 Mg alloy Inorganic materials 0.000 description 2
- 239000000956 alloy Substances 0.000 description 2
- SNAAJJQQZSMGQD-UHFFFAOYSA-N aluminum magnesium Chemical compound [Mg].[Al] SNAAJJQQZSMGQD-UHFFFAOYSA-N 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 230000009466 transformation Effects 0.000 description 2
- 238000009412 basement excavation Methods 0.000 description 1
- 239000004568 cement Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/25—Methods for stimulating production
- E21B43/26—Methods for stimulating production by forming crevices or fractures
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B34/00—Valve arrangements for boreholes or wells
- E21B34/06—Valve arrangements for boreholes or wells in wells
- E21B34/14—Valve arrangements for boreholes or wells in wells operated by movement of tools, e.g. sleeve valves operated by pistons or wire line tools
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Abstract
The invention discloses a coal mine underground branch drilling staged fracturing permeability increasing method and a pressure pumping integrated device, wherein the permeability increasing method adopts a dissolvable fracturing ball pitching staged fracturing mode, and fracturing liquid is replaced by a saline solution after fracturing; the dissolvable fracturing ball is made of low-density resin materials, the specific gravity of the dissolvable fracturing ball is smaller than that of fracturing fluid, the dissolvable fracturing ball can be soaked in salt solution to be dissolved, and a piston of a sliding sleeve in a fracturing tool for fracturing can keep the position unchanged after the fracturing fluid pushes the sliding sleeve to move and release pressure. The pressure and suction integrated device is used for coal seam gas extraction after fracturing is carried out by the method. The invention has the advantages that the permeability increasing method can realize multi-section staged fracturing, can be conveniently applied to the construction of an upper hole under a coal mine, and can realize gas extraction by using the fracturing pipe after the fracturing ball is dissolved by the saline solution; the pressure and pumping integrated device has the functions of fracturing and pumping, can effectively improve the pumping efficiency and reduce the pumping cost.
Description
Technical Field
The invention belongs to the field of coal bed gas development, and particularly relates to a coal mine underground branch drilling staged fracturing permeability increasing method and a pressure pumping integrated device.
Background
Due to the complexity of geological conditions of coal in Chongqing areas, after main coal measure strata are deposited, strong tectonic movement is carried out, coal body structures are damaged strongly, coal beds of the Chongqing areas are mostly soft coal beds, the Chongqing areas have the characteristics of low coal bed hardness, high gas pressure and content, poor air permeability and the like, and the difficulty in extracting coal bed gas (gas) is high. Through many years of exploration, the hydraulic fracturing permeability increase is one of key technical measures for gas extraction of a low-permeability coal seam, a core technology of water treatment of gas and a working mode of firstly pressing and then pumping are formed, and a certain effect is achieved. However, this method has the following limitations: (1) the conventional fracturing drilling mainly adopts floor roadway cross-layer drilling or the coal seam bedding drilling for fracturing, and the construction amount of the roadway and the drilling is large and the cost is high; (2) each fracturing drill hole is usually fractured at the bottom of the hole only once, so that the number of the fracturing drill holes is large, the hole sealing and fracturing cost is high, the single-hole fracture influence range is small, the gas extraction quantity is small, the drill hole utilization rate is low, the extraction efficiency is low, the standard reaching time is long, and the extraction, extraction and excavation deployment are short; the method for increasing the permeability of large-area regionalized hydraulic fracturing and efficiently extracting gas is urgently needed to be developed.
In recent years, with the development of unconventional oil and gas industry, horizontal well drilling technology and multi-stage staged fracturing technology are rapidly developed, such as the method for permeability increasing and gas extraction of coal mine underground coal seam long drilling staged fracturing published by the Chinese patent document CN 108643877A. Meanwhile, the horizontal well drilling technology is widely applied to long underground coal mine borehole drilling, but in the aspect of staged fracturing technology, due to the limitation of narrow space in the underground coal mine, huge ground fracturing equipment cannot be accommodated, the power of an underground fracturing pump is limited, the construction displacement is far smaller than that of the ground fracturing pump, and the requirement for whole fracturing permeability increase of long boreholes cannot be met, so that the technology for staged fracturing permeability increase of long underground coal mine boreholes and branch boreholes is urgently needed to be researched. The uniform permeability increase of the regional coal seam is realized, the gas extraction effect is improved, and the gas dynamic disaster risk is reduced.
For the staged fracturing device, in the development of oil and gas fields, tools such as open hole packers, soluble fracturing balls and fracturing sliding sleeves with soluble fracturing ball seats are used, but a certain problem exists when part of the tools are used for underground construction of coal mines, and therefore improvement and optimization are needed on the basis.
In addition, at present, research on a long borehole staged fracturing technology of a coal mine underground has been carried out domestically, mainly aiming at a casing pipe under a directional long borehole along a coal seam, and staged packing and multistage fracturing are realized in the casing pipe, but the coal seam in southern areas is generally softer, the difficulty in implementing the long borehole in the coal seam is high, only long boreholes with branches on a top plate or a bottom plate can be implemented (namely, a main borehole of a long borehole is implemented on the top plate or the bottom plate of a target coal seam, and then branches are formed from the main borehole and enter the coal seam), the difficulty in placing the casing pipe in the long boreholes with branches is high, and the formed branch boreholes can be sealed by implementing cement slurry fixed holes in the branch boreholes, so that the fracturing transformation of the coal seam cannot be effectively carried out during fracturing, and therefore, a technical method for staged fracturing of open-hole long boreholes and efficient gas. Meanwhile, the power of the mining fracturing pump is small, most construction discharge capacity is below 1 square/hour, the construction discharge capacity is generally more than several square/minute according to the ground hydraulic fracturing experience of the oil and gas industry, the underground construction discharge capacity of the coal mine is far smaller than the ground fracturing, and the coal seam cannot be subjected to better volume transformation. Therefore, a method for increasing the underground hydraulic fracturing construction discharge capacity of the coal mine needs to be explored, and the construction discharge capacity and the fracturing effect are improved to the maximum extent.
The dissolvable fracturing ball in a staged fracturing device is made of an aluminum magnesium alloy material commonly used in oil and gas field development, the fracturing ball is high in density and free of any problem when being used for underground well drilling, however, most underground coal mine gas treatment holes are upward holes, the power of a fracturing pump for coal mines is far lower than that of a fracturing pump for ground well drilling, the construction discharge capacity is less than 1 cubic meter per minute, the available fracturing ball made of the aluminum magnesium alloy material is difficult to send to a preset position in a fracturing hole, and corresponding improvement is needed.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a staged fracturing permeability-increasing method for a branch drill hole in a coal mine. The second purpose of the invention is to provide a pressure and suction integrated device for realizing the integrated operation of dissolving ball fracturing and gas extraction, so as to reduce the extraction cost.
In order to achieve the first object, the invention adopts the following technical scheme.
A coal mine underground branch drilling staged fracturing permeability-increasing method adopts a dissolvable fracturing ball pitching staged fracturing mode, and adopts a salt solution for fracturing fluid replacement after fracturing; the dissolvable fracturing ball is made of low-density resin materials, the specific gravity of the dissolvable fracturing ball is smaller than that of fracturing fluid, the dissolvable fracturing ball can be soaked in salt solution to be dissolved, and a piston of a sliding sleeve in a fracturing tool for fracturing can keep the position unchanged after the fracturing fluid pushes the sliding sleeve to move and release pressure.
By adopting the scheme, the invention adopts a pitching staged fracturing mode, so that staged fracturing of a plurality of branch holes of a long drilled hole in a coal mine can be conveniently realized, and each stage corresponds to one branch hole for staged fracturing; the dissolvable fracturing ball is made of low-density resin materials, the specific gravity of the dissolvable fracturing ball is smaller than that of the fracturing fluid and is close to that of clear water, and staged fracturing of upward drilled holes in a coal mine can be achieved; meanwhile, the piston of the sliding sleeve in the fracturing tool can keep the position unchanged after the fracturing fluid pushes to move and release the pressure, so that the inner space of the fracture and the inner space of the fracturing tool are smooth, and the soluble ball can be dissolved after being soaked in the salt solution full solution.
Preferably, the salt solution is injected as a displacement fluid for the fracturing fluid after completion of all staged fracturing. Compared with staged injection of replacement fluid, the dissolvable fracturing ball with the plugging effect caused by the replacement fluid can be prevented from being dissolved in the fracturing process, the plugging effect is weakened, and the staged fracturing effect is reduced.
Further preferably, the method is carried out according to the following steps:
firstly, determining a hole distribution rock stratum arranged in a long drilling main hole, and selecting a rock stratum which is stable in lithology and difficult to expand when meeting water as a hole distribution layer of a branched long drilling main hole on a coal seam top plate or a coal seam bottom plate;
secondly, drilling a long main hole, arranging a drilling site in a coal mine roadway, drilling according to a preset drilling track by using a mining kilometer directional drilling machine, controlling the main hole in a stable rock stratum of a top plate or a bottom plate, branching the main hole to enter a target coal seam, wherein the drilling length of the main hole is more than 100 meters, and the hole diameter is not less than 120 mm;
thirdly, preparing fracturing, namely performing on-site preparation work of a hydraulic fracturing pump, a sand adding pump set, a high-pressure manifold, a staged packing and fracturing tool, fracturing fluid and fracturing sand according to fracturing construction requirements;
fourthly, determining a connection scheme of the fracturing tool and the hole sealing tool, finding out the position and the depth of the opening of the branch hole according to the hole forming data of the long branch drill hole so as to ensure that each branch hole is contained in one fracturing section, and determining the connection scheme of the fracturing tool and the hole sealing tool according to the principle that each sliding sleeve is placed at the opening of the branch hole;
fifthly, placing a drilling hole dredging and fracturing device, removing sediments in the hole through well dredging and well washing, placing a main body part of the fracturing device formed by a fracturing tool and a hole sealing tool into the drilling hole to a set position, and exposing the opening of a fracturing pipe of the fracturing tool out of the drilling hole;
sixthly, connecting the fracturing tool with a fracturing pump, and connecting an exposed pipe orifice of the fracturing tool with the fracturing pump through a high-pressure pipeline;
seventhly, pressure test verification is carried out, the fracturing pump test pipeline is started to verify the sealing condition, a packer is started by injecting water and pressurizing, and the setting condition is verified; if the fault is qualified, executing the next step, if the fault is not qualified, circularly executing the step after searching and eliminating the fault;
eighthly, fracturing the bottom section of the hole, starting a fracturing pump to perform pressure injection, gradually increasing the injection pressure to a fracturing pressure range of a set value, pushing a piston in the bottom differential pressure sliding sleeve to move by fracturing fluid, opening a through hole in the pipe wall of the differential pressure sliding sleeve, and performing fracturing construction on the bottom section of the hole;
ninth, throwing balls for fracturing, and stopping a pump for pressure relief after fracturing construction of the previous fracturing stage is completed; putting a dissolvable fracturing ball matched with a fracturing sliding sleeve adjacent to the previous fracturing section into a fracturing pipe of a fracturing tool, starting a fracturing pump, and delivering the dissolvable fracturing ball to a ball seat of the fracturing sliding sleeve of the corresponding section by fracturing fluid according to a pressure value lower than the fracturing pressure to realize the sealing of the interior of the fracturing pipe and the fracturing section;
step ten, boosting pressure and fracturing, continuously injecting water and pressurizing to enable the pressure of the fracturing fluid to be raised to a fracturing pressure range, pushing a piston in the fracturing sliding sleeve to move through a dissolvable fracturing ball, opening a through hole in the pipe wall of the fracturing sliding sleeve, and performing fracturing construction of the section;
step ten, judging whether a fracturing section which is adjacent to the section has a fracturing section which is not fractured or not after fracturing construction is finished; if yes, returning to the ninth step; if not, executing the next step;
step ten, injecting a salt solution, and injecting the salt solution with a set proportion to replace fracturing fluid, wherein the salt solution is used for dissolving the fracturing ball;
and step thirteen, sealing holes and maintaining pressure, wherein after a set amount of saline solution is injected, the sealing holes and the maintaining pressure are carried out for a set time, so that after the fracturing balls are dissolved, all fracturing sections can be communicated through fracturing pipes, and pressure relief is carried out for gas extraction.
When the pressure difference sliding sleeve and the fracturing sliding sleeve are manufactured, the diameter of the through hole in the wall of the sliding sleeve meets the requirement of the drainage drift diameter, and the aperture of the sliding sleeve is larger than that of the sliding sleeve only used for fracturing. The staged fracturing construction is ensured to be smooth, and extraction by utilizing a fracturing device can be realized.
Preferably, after the hole sealing tool in the fifth step is placed, a temporary hole sealing section is further performed on the hole opening, and the length of the temporary hole sealing section is larger than 10 meters. So as to ensure the firm installation of the hole sealing tool and ensure the safe use.
Preferably, the set value of the fracturing pressure is 20MPa to 37 MPa. So that the coal bed is fully fractured and the permeability increasing effect is improved.
Preferably, the fracturing pump consists of a single pump, or a double pump or a plurality of pumps are connected in parallel to form a fracturing pump group. The fracturing fluid can be selected according to different occasions and fracturing requirements, and flexible application is ensured. In the fracturing pump set scheme, only 1 fracturing pump is started when the dissolvable fracturing ball is delivered. Reduce energy consumption and ensure smooth and reliable ball throwing.
In order to achieve the second object, the present invention adopts the following technical solutions.
A pressure pumping integrated device for branch drilling in a coal mine well comprises a fracturing pipe, wherein a plurality of fracturing sliding sleeves are connected to the fracturing pipe in series, a pipe section of the fracturing pipe, which is close to the bottom of a drilling hole, is connected with a pressure difference sliding sleeve in series, and the far end of the pressure difference sliding sleeve is provided with a guide shoe through the pipe section at the bottom of the drilling hole; from the hole bottom of the drill hole to the hole opening, the inner hole channels of the ball seat on the fracturing sliding sleeve are sequentially enlarged and can pass through the dissolvable fracturing ball which is close to the fracturing section and faces the hole bottom direction; the fracturing sliding sleeve and the differential pressure sliding sleeve are provided with a naked hole packer in the direction of the drilling hole opening, and the naked hole packer is fixedly connected to the fracturing pipe; a pressure relief bypass is arranged at the end part of the fracturing pipe exposed out of the drill hole, a pressure relief valve is arranged on the pressure relief bypass, and an outlet end of the pressure relief bypass is provided with an interface connected with a gas-water separator; the pressure relief bypass is detachably connected with a gas-water separator through the interface; the fracturing sliding sleeve and the differential pressure sliding sleeve are both composed of a piston and a pipe sleeve, a one-way sliding fit structure only allowing the piston to move in one direction is formed between the piston and the pipe sleeve, and the one-way sliding fit structure is formed by matching a spring piece and one-way teeth; the wall of the pipe sleeve is provided with a through hole penetrating through the pipe wall, the piston can move under the pushing of external force to open the through hole, and the piston of the fracturing sliding sleeve forms a ball seat with the inner hole channel.
By adopting the device of the scheme, the plurality of fracturing sliding sleeves are connected in series on the fracturing pipe, and the differential pressure sliding sleeves are connected in series on the pipe section of the fracturing pipe close to the bottom of the drilled hole, so that a structure suitable for a staged fracturing mode of ball-throwing fracturing is formed; meanwhile, the gas-water separator is arranged at the pipe opening of the fracturing pipe, so that the gas-water separator can be connected with a gas extraction system, the purpose that the fracturing pipe is used as a gas extraction pipe is achieved, gas extraction preparation work is reduced, extraction efficiency can be effectively improved, and extraction cost is reduced. The fracturing sliding sleeve is characterized in that the piston of the differential pressure sliding sleeve does not form a ball seat structure and is not provided with an internal channel, and the piston slides under the high-pressure pushing of fracturing fluid to open a through hole in the wall of the sliding sleeve; but with prior art's difference point, also be the common characteristics of differential pressure sliding sleeve and fracturing sliding sleeve in this application, be formed with the one-way sliding fit structure that only supplies piston one-way removal between piston and the pipe box promptly to keep open mode after the release, be convenient for take out and adopt coal seam gas.
Preferably, the open hole packer is a bag type packer, and the inside of the packer is communicated with the inside of the fracturing pipe through a first one-way valve. So that the hole sealing pressure of the hole sealer is increased along with the increase of the fracturing pressure, and the purpose of reliable plugging is achieved.
Preferably, the end part of the fracturing pipe, which is exposed out of the drilling hole, is also provided with a ball throwing bypass with a ball throwing port, and the ball throwing bypass is provided with a valve capable of sealing the ball throwing port. The purpose of convenient ball injection is realized, and reliable sealing can be realized after ball injection.
The invention has the advantages that the permeability increasing method can realize multi-section staged fracturing, can be conveniently applied to the construction of an upper hole under a coal mine, and can realize gas extraction by using the fracturing pipe after the fracturing ball is dissolved by the saline solution; the pressure and pumping integrated device has the functions of fracturing and pumping, can effectively improve the pumping efficiency and reduce the pumping cost.
Drawings
Fig. 1 is a schematic structural view of the integrated press-drawing device of the present invention. This figure is also used to illustrate staged fracturing methods.
Fig. 2 is a schematic structural diagram of a sliding sleeve part in the device of the invention.
Detailed Description
The invention will be further described with reference to the drawings, but the invention is not limited thereby within the scope of the embodiments described.
The method comprises the following steps of:
firstly, determining a hole distribution rock stratum arranged in a long drilling main hole, and selecting a rock stratum which is stable in lithology and difficult to expand when meeting water as a hole distribution layer of a branched long drilling main hole on a coal seam top plate or a coal seam bottom plate;
secondly, drilling a long main hole, arranging a drilling site in a coal mine roadway, drilling according to a preset drilling track by using a mining kilometer directional drilling machine, controlling the main hole in a stable rock stratum of a top plate or a bottom plate, branching the main hole to enter a target coal seam, wherein the drilling length of the main hole is more than 100 meters, and the hole diameter is not less than 120 mm;
thirdly, preparing fracturing, namely performing on-site preparation work of a hydraulic fracturing pump, a sand adding pump set, a high-pressure manifold, a staged packing and fracturing tool, fracturing fluid and fracturing sand according to fracturing construction requirements;
fourthly, determining a connection scheme of the fracturing tool and the hole sealing tool, finding out the position and the depth of the opening of the branch hole according to the hole forming data of the long branch drill hole so as to ensure that each branch hole is contained in one fracturing section, and determining the connection scheme of the fracturing tool and the hole sealing tool according to the principle that each sliding sleeve is placed at the opening of the branch hole;
fifthly, placing the drilling hole dredging and fracturing device, removing sediments in the hole through well dredging and well washing, and placing a main body part of the fracturing device formed by the fracturing tool and the hole sealing tool into the drilling hole to a set position;
sixthly, connecting the fracturing tool with a fracturing pump, and connecting an exposed pipe orifice of the fracturing tool with the fracturing pump through a high-pressure pipeline;
seventhly, pressure test verification is carried out, the fracturing pump test pipeline is started to verify the sealing condition, a packer is started by injecting water and pressurizing, and the setting condition is verified; if the fault is qualified, executing the next step, if the fault is not qualified, circularly executing the step after searching and eliminating the fault;
eighthly, fracturing the bottom section of the hole, starting a fracturing pump to perform pressure injection, gradually increasing the injection pressure to a fracturing pressure range of a set value, pushing a piston in the bottom differential pressure sliding sleeve to move by fracturing fluid, opening a through hole in the pipe wall of the differential pressure sliding sleeve, and performing fracturing construction on the bottom section of the hole;
ninth, throwing balls for fracturing, and stopping a pump for pressure relief after fracturing construction of the previous fracturing stage is completed; putting a dissolvable fracturing ball matched with a fracturing sliding sleeve adjacent to the previous fracturing section into a fracturing pipe of a fracturing tool, starting a fracturing pump, and delivering the dissolvable fracturing ball to a ball seat of the fracturing sliding sleeve of the corresponding section by fracturing fluid according to a pressure value lower than the fracturing pressure to realize the sealing of the interior of the fracturing pipe and the fracturing section;
step ten, boosting pressure and fracturing, continuously injecting water and pressurizing to enable the pressure of the fracturing fluid to be raised to a fracturing pressure range, pushing a piston in the fracturing sliding sleeve to move through a dissolvable fracturing ball, opening a through hole in the pipe wall of the fracturing sliding sleeve, and performing fracturing construction of the section;
step ten, judging whether a fracturing section which is adjacent to the section has a fracturing section which is not fractured or not after fracturing construction is finished; if yes, returning to the ninth step; if not, executing the next step;
step ten, injecting a salt solution, and injecting the salt solution with a set proportion to replace fracturing fluid, wherein the salt solution is used for dissolving the fracturing ball;
and step thirteen, sealing holes and maintaining pressure, wherein after a set amount of saline solution is injected, the sealing holes and the maintaining pressure are carried out for a set time, so that after the fracturing balls are dissolved, all fracturing sections can be communicated through fracturing pipes, and pressure relief is carried out for gas extraction.
When the pressure difference sliding sleeve and the fracturing sliding sleeve are manufactured, the diameter of the through hole in the wall of the sliding sleeve meets the requirement of the drainage drift diameter, and the aperture of the sliding sleeve is larger than that of the sliding sleeve only used for fracturing. After the hole sealing tool in the fifth step is placed, a temporary hole sealing section is further included in the hole opening, the length of the temporary hole sealing section 11 is larger than 10 meters, and the temporary hole sealing section is required to meet sealing requirements of not leaking during extraction. The set value of the fracturing pressure is 20MPa to 37 MPa; the fracturing pump consists of a single pump or a double pump or a plurality of pumps which are connected in parallel to form a fracturing pump group. In the fracturing pump set scheme, only 1 fracturing pump is started when the dissolvable fracturing ball is delivered.
Embodiment 2, refer to fig. 1 and 2, a pressure pumping integrated device for coal mine underground branch drilling comprises a fracturing pipe 1, wherein the fracturing pipe 1 is connected with a plurality of fracturing sliding sleeves 2 in series, a pipe section of the fracturing pipe 1 close to the bottom of a drilling hole is connected with a pressure difference sliding sleeve 3 in series, and the far end of the pressure difference sliding sleeve 3 is provided with a guide shoe 5 through the pipe section at the bottom of the hole; from the hole bottom of the drilled hole to the orifice, the inner hole channels of the ball seat on the fracturing sliding sleeve 2 are sequentially enlarged, and the dissolvable fracturing balls of each fracturing section can be smoothly delivered in place in the staged fracturing process from the hole bottom to the orifice direction through the dissolvable fracturing balls for fracturing close to the fracturing sections towards the hole bottom direction; the fracturing sliding sleeve 2 and the differential pressure sliding sleeve 3 are provided with a naked hole packer 4 in the direction of the drilling hole opening, and the naked hole packer 4 is fixedly connected to the fracturing pipe 1; a pressure relief bypass 10 is arranged at the end part of the fracturing pipe 1 exposed out of the drill hole, a pressure relief valve 6 is arranged on the pressure relief bypass 10, and an outlet end of the pressure relief bypass 10 is provided with a connector connected with a gas-water separator 7; the pressure relief bypass 10 is detachably connected with a gas-water separator 7 through the interface, and the gas-water separator 7 is provided with a gas outlet 7a and a liquid outlet 7 b; the fracturing sliding sleeve 2 and the differential pressure sliding sleeve 3 are both composed of a piston and a pipe sleeve, a one-way sliding fit structure which only allows the piston to move in one direction is formed between the piston and the pipe sleeve, and the one-way sliding fit structure is formed by matching a spring piece 17 and one-way teeth; the spring piece 17 is fixed on the pipe sleeve 18, the one-way teeth are arranged on the piston 19, the wall of the pipe sleeve is provided with a through hole 20 penetrating through the pipe wall, the piston can move under the pushing of external force to open the through hole, and the piston of the fracturing sliding sleeve 2 forms a ball seat with the inner hole channel, and the ball seat is used for seating the dissoluble fracturing ball 16. When the differential pressure sliding sleeve and the fracturing sliding sleeve are manufactured, the diameter of the through hole in the sleeve wall of the differential pressure sliding sleeve and the fracturing sliding sleeve meets the requirement of the extraction drift diameter, and the aperture of the differential pressure sliding sleeve is larger than that of the sliding sleeve only used for fracturing.
The open hole packer 4 is a bag type packer, and the inside of the packer is communicated with the inside of the fracturing pipe 1 through a first one-way valve 8. The end part of the fracturing pipe 1 exposed out of the drill hole is also provided with a ball throwing bypass 9 with a ball throwing port and a pressure gauge 15, and the ball throwing bypass is provided with a valve 12 capable of sealing the ball throwing port; a second one-way valve 13 is arranged at the pipe orifice of the fracturing pipe 1, and the second one-way valve 13 is used for fracturing and pressure maintaining; the pipe orifice of the fracturing pipe 1 is provided with a pipeline interface 14, and the fracturing pipe 1 is connected with a fracturing pump or a fracturing pump set through the pipeline interface 14 by a high-pressure pipeline.
In the implementation, the number of the fracturing sliding sleeves 2 is three, the pressure difference sliding sleeve 3 is provided with 1 fracturing sliding sleeve which is close to the hole bottom of the long drilled hole, from the hole opening to the hole bottom, inner hole channels of pistons on the three fracturing sliding sleeves 2 are gradually increased, and a dissolvable fracturing ball which is seated on the fracturing sliding sleeve 2 which is close to the pressure difference sliding sleeve 3 can penetrate through the inner hole channels of the other two fracturing sliding sleeves 2 facing to the hole opening direction; the dissolvable fracturing ball seated on the fracturing sliding sleeve 2 at the intermediate position can pass through the internal bore passage of the fracturing sliding sleeve 2 near the orifice.
The foregoing shows and describes the general principles and broad features of the present invention and advantages thereof. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.
Claims (10)
1. A coal mine underground branch drilling staged fracturing permeability-increasing method is characterized in that a dissolvable fracturing ball pitching staged fracturing mode is adopted, and a saline solution is adopted for fracturing fluid replacement after fracturing; the dissolvable fracturing ball is made of low-density resin materials, the specific gravity of the dissolvable fracturing ball is smaller than that of fracturing fluid, the dissolvable fracturing ball can be soaked in salt solution to be dissolved, and a piston of a sliding sleeve in a fracturing tool for fracturing can keep the position unchanged after the fracturing fluid pushes the sliding sleeve to move and release pressure.
2. The method of claim 1, wherein the salt solution is injected as a displacement fluid for the fracturing fluid after completion of all staged fracturing.
3. A method according to claim 1 or 2, characterized by the following steps:
firstly, determining a hole distribution rock stratum arranged in a long drilling main hole, and selecting a rock stratum which is stable in lithology and difficult to expand when meeting water as a hole distribution layer of a branched long drilling main hole on a coal seam top plate or a coal seam bottom plate;
secondly, drilling a long main hole, arranging a drilling site in a coal mine roadway, drilling according to a preset drilling track by using a mining kilometer directional drilling machine, controlling the main hole in a stable rock stratum of a top plate or a bottom plate, branching the main hole to enter a target coal seam, wherein the drilling length of the main hole is more than 100 meters, and the hole diameter is not less than 120 mm;
thirdly, preparing fracturing, namely performing on-site preparation work of a hydraulic fracturing pump, a sand adding pump set, a high-pressure manifold, a staged packing and fracturing tool, fracturing fluid and fracturing sand according to fracturing construction requirements;
fourthly, determining a connection scheme of the fracturing tool and the hole sealing tool, finding out the position and the depth of the opening of the branch hole according to the hole forming data of the long branch drill hole so as to ensure that each branch hole is contained in one fracturing section, and determining the connection scheme of the fracturing tool and the hole sealing tool according to the principle that each sliding sleeve is placed at the opening of the branch hole;
fifthly, placing a drilling hole dredging and fracturing device, removing sediments in the hole through well dredging and well washing, placing a main body part of the fracturing device formed by a fracturing tool and a hole sealing tool into the drilling hole to a set position, and exposing the opening of a fracturing pipe of the fracturing tool out of the drilling hole;
sixthly, connecting the fracturing tool with a fracturing pump, and connecting an exposed pipe orifice of the fracturing tool with the fracturing pump through a high-pressure pipeline;
seventhly, pressure test verification is carried out, the fracturing pump test pipeline is started to verify the sealing condition, a packer is started by injecting water and pressurizing, and the setting condition is verified; if the fault is qualified, executing the next step, if the fault is not qualified, circularly executing the step after searching and eliminating the fault;
eighthly, fracturing the bottom section of the hole, starting a fracturing pump to perform pressure injection, gradually increasing the injection pressure to a fracturing pressure range of a set value, pushing a piston in the bottom differential pressure sliding sleeve to move by fracturing fluid, opening a through hole in the pipe wall of the differential pressure sliding sleeve, and performing fracturing construction on the bottom section of the hole;
ninth, throwing balls for fracturing, and stopping a pump for pressure relief after fracturing construction of the previous fracturing stage is completed; putting a dissolvable fracturing ball matched with a fracturing sliding sleeve adjacent to the previous fracturing section into a fracturing pipe of a fracturing tool, starting a fracturing pump, and delivering the dissolvable fracturing ball to a ball seat of the fracturing sliding sleeve of the corresponding section by fracturing fluid according to a pressure value lower than the fracturing pressure to realize the sealing of the interior of the fracturing pipe and the fracturing section;
step ten, boosting pressure and fracturing, continuously injecting water and pressurizing to enable the pressure of the fracturing fluid to be raised to a fracturing pressure range, pushing a piston in the fracturing sliding sleeve to move through a dissolvable fracturing ball, opening a through hole in the pipe wall of the fracturing sliding sleeve, and performing fracturing construction of the section;
step ten, judging whether a fracturing section which is adjacent to the section has a fracturing section which is not fractured or not after fracturing construction is finished; if yes, returning to the ninth step; if not, executing the next step;
step ten, injecting a salt solution, and injecting the salt solution with a set proportion to replace fracturing fluid, wherein the salt solution is used for dissolving the fracturing ball;
and step thirteen, sealing holes and maintaining pressure, wherein after a set amount of saline solution is injected, the sealing holes and the maintaining pressure are carried out for a set time, so that after the fracturing balls are dissolved, all fracturing sections can be communicated through fracturing pipes, and pressure relief is carried out for gas extraction.
4. The method of claim 3, wherein after the placing of the sealing tool in the fifth step, the method further comprises the step of performing a temporary sealing section on the hole opening, wherein the length of the temporary sealing section is greater than 10 meters.
5. The method of claim 3, wherein the fracture pressure set point is 20MPa to 37 MPa.
6. The method of claim 3, wherein the frac pump consists of a single pump or a dual or multiple pumps in parallel to form a frac pump group.
7. The method of claim 6, wherein in the frac pump set protocol, only 1 of the frac pumps is activated when delivering the dissolvable frac ball.
8. The pressure pumping integrated device for the underground branch drilling of the coal mine is characterized by comprising a fracturing pipe (1), wherein a plurality of fracturing sliding sleeves (2) are connected to the fracturing pipe (1) in series, a pipe section, close to the bottom of a drilling hole, of the fracturing pipe (1) is connected with a pressure difference sliding sleeve (3) in series, and a guide shoe (5) is arranged at the far end of the pressure difference sliding sleeve (3) through the pipe section at the bottom of the hole; from the hole bottom of the drilling hole to the hole opening, the inner hole channels of the ball seat on the fracturing sliding sleeve (2) are sequentially enlarged and can pass through the dissolvable fracturing ball which is close to the fracturing section and faces the hole bottom direction; the fracturing sliding sleeve (2) and the pressure difference sliding sleeve (3) are provided with a naked hole packer (4) in the direction of the drilling hole opening, and the naked hole packer (4) is fixedly connected to the fracturing pipe (1); a pressure relief bypass (10) is arranged at the end part of the fracturing pipe (1) exposed out of the drill hole, a pressure relief valve (6) is arranged on the pressure relief bypass (10), and an outlet end of the pressure relief bypass (10) is provided with a connector connected with a gas-water separator (7); the pressure relief bypass (10) is detachably connected with a gas-water separator (7) through the interface; the fracturing sliding sleeve (2) and the differential pressure sliding sleeve (3) are both composed of a piston and a pipe sleeve, a one-way sliding fit structure which only allows the piston to move in one direction is formed between the piston and the pipe sleeve, and the one-way sliding fit structure is formed by matching a spring piece and one-way teeth; the wall of the pipe sleeve is provided with a through hole penetrating through the pipe wall, the piston can move under the pushing of external force to open the through hole, and the piston of the fracturing sliding sleeve (2) forms a ball seat with the inner hole channel.
9. The device according to claim 8, characterized in that the open hole packer (4) is a bag type packer, the inside of which is communicated with the inside of the fracturing pipe (1) through a first one-way valve (8).
10. The device according to claim 8, characterized in that the end of the fracturing pipe (1) exposed out of the borehole is further provided with a ball-throwing bypass with a ball-throwing port, and the ball-throwing bypass is provided with a valve capable of closing the ball-throwing port.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112127854A (en) * | 2020-09-22 | 2020-12-25 | 重庆市能源投资集团科技有限责任公司 | Staged fracturing and extraction method for long drill hole of coal seam and pressure-extraction integrated device |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112127854A (en) * | 2020-09-22 | 2020-12-25 | 重庆市能源投资集团科技有限责任公司 | Staged fracturing and extraction method for long drill hole of coal seam and pressure-extraction integrated device |
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