A liquid CO2 phase change and hydraulic fracturing device while drilling and its use method

Abstract

The invention discloses a combined fracturing device for phase change and hydraulic fracturing of liquid CO2 while drilling, comprising a sealing unit, a connecting unit and an additional unit. The sealing unit comprises a front sealing device and a rear sealing device. The connecting unit comprises a composite connector, a connecting ring, a high-pressure connector, a wire connector and a drill pipe. The additional unit comprises a hydraulic fracturing pipe and a liquid CO2 phase change fracturing pipe. The front sealing device and the rear sealing device are assembled at one end of different drill pipes. The invention also discloses a method for using the combined fracturing device for phase change and hydraulic fracturing of liquid CO2 while drilling. The invention designs a combined fracturing device for phase change and hydraulic fracturing of liquid CO2 while drilling. The sealing unit and the additional unit can be mounted on the drill pipe and connected to each other through the connecting unit, thereby realizing the work while drilling. During the construction process of drilling measures, the additional unit can be transported to the combined fracturing position. When the drilling is completed, the liquid CO2 phase change and hydraulic fracturing can be carried out, thereby reducing the overall construction process and improving the fracturing work efficiency.

Description

Technical Field

[0001] The invention belongs to the technical field of coal seam permeability enhancement equipment, and in particular provides a liquid CO2 phase change and hydraulic combined fracturing device while drilling and a use method thereof. Background Art

[0002] Affected by geological conditions, most coal seams in my country have low permeability, resulting in poor gas extraction effects in such coal seams, which is not conducive to safe production of coal seams. In order to increase the permeability of coal seams, a variety of coal seam permeability enhancement technologies have been developed and applied, such as hydraulic fracturing, hydraulic cutting, hydraulic punching, deep hole blasting, liquid CO2 phase change, permeability enhancement fluid, microorganisms, and mechanical hole expansion enhancement. Through the actual application effects of various permeability enhancement technologies on coal mine sites, a single coal seam permeability enhancement technology has certain limitations. Therefore, integrating multiple coal seam permeability enhancement technologies will definitely be one of the development directions of coal seam permeability enhancement technologies in the future. To this end, a combined fracturing coal seam permeability enhancement technology combining liquid CO2 phase change and hydraulic fracturing has been proposed. However, the current application of this technology is very complicated. After the measure drilling construction is completed and the drill is withdrawn, the liquid CO2 phase change fracturing tube must first be placed in the borehole, and then all of it must be taken out after blasting. Then the hydraulic fracturing equipment is placed in the borehole for hydraulic fracturing. The operation steps are relatively complicated, especially when the measure borehole is subjected to segmented combined fracturing. The overall operation is particularly cumbersome, time-consuming and labor-intensive. Summary of the invention

[0003] In order to solve the above problems, the present invention provides a liquid CO2 phase change and hydraulic fracturing device while drilling and a method for using the device.

[0004] To achieve the above-mentioned purpose, the technical scheme adopted by the present invention is: a liquid CO2 phase change and hydraulic fracturing device while drilling, comprising a sealing unit, a connecting unit and an additional investment unit, the sealing unit comprising a front sealer and a rear sealer, the connecting unit comprising a composite connector, a connecting ring, a high-pressure connector, a wire connector and a drill pipe, the additional investment unit comprising a hydraulic fracturing pipe and a liquid CO2 phase change fracturing pipe, the front sealer and the rear sealer are assembled at one end of different drill pipes, and the hydraulic fracturing pipe and the liquid CO2 phase change fracturing pipe are assembled between the front sealer and the rear sealer, the front sealer, the hydraulic fracturing pipe, the liquid CO2 phase change fracturing pipe, and the rear sealer are connected by a connecting ring, the composite connector is assembled at the ends of the front sealer, the hydraulic fracturing pipe, the liquid CO2 phase change fracturing pipe, the rear sealer and the drill pipe, and the composite connectors are connected by a high-pressure connector, and a wire connector is arranged between the liquid CO2 phase change fracturing pipe and the rear sealer.

[0005] Furthermore, the front hole sealer comprises a front hole sealer expansion capsule, a front hole sealer boss, a front hole sealer frame, a front hole sealer fixing platform, a first expansion balloon and a first expansion balloon connecting tube, the front hole sealer frustum is integrally formed at both ends of the front hole sealer frame, the front hole sealer expansion capsule is wrapped between the outside of the front hole sealer frame and the two front hole sealer frustums, the two front hole sealer bosses are respectively assembled on the outer ends of the two front hole sealer frustums, the front hole sealer frame is provided with a through front hole sealer fluid channel, the outer surface of one of the front hole sealer bosses is provided with a front hole sealer external thread, and the inner surface of the other front hole sealer boss is provided with The front hole sealer has an internal thread, a front hole sealer slot, a first liquid injection port for an expansion capsule and a first liquid injection port for a first expansion balloon are provided on the outer surface of one of the front hole sealer truncated cones, the front hole sealer fixing platform is fixedly mounted on the inner end of the front hole sealer truncated cone, an internal liquid injection port for an expansion capsule connected to the first liquid injection port for the expansion capsule and a first expansion balloon connecting tube connected to the first liquid injection port for the first expansion balloon are provided on the inner end of the first expansion balloon connecting tube, the first expansion balloon is assembled on the inner end of the first expansion balloon connecting tube, the outer surface of the front hole sealer frame is provided with a first balloon chamber connected to the fluid channel of the front hole sealer, and the first expansion balloon is located in the first balloon chamber;

[0006] The rear hole sealer comprises a rear hole sealer frame, a rear hole sealer expansion capsule, a rear hole sealer boss, a rear hole sealer fixing platform and a rear hole sealer round platform, and the rear hole sealer frame, the rear hole sealer expansion capsule, the rear hole sealer boss, the rear hole sealer fixing platform and the rear hole sealer round platform have the same structure as the front hole sealer frame, the front hole sealer expansion capsule, the front hole sealer boss, the front hole sealer fixing platform and the front hole sealer round platform, and both ends of the rear hole sealer frame are equipped with rear hole sealer round platforms, and the two rear hole sealers are The hole sealer boss is assembled on the outer ends of the two rear hole sealer truncated cones, the two rear hole sealer fixing platforms are assembled on the inner ends of the two rear hole sealer truncated cones, the rear hole sealer expansion capsule is wrapped on the outside of the rear hole sealer frame, and the outer ends of the two rear hole sealer truncated cones are provided with a fourth liquid injection port for the expansion capsule, a first connecting port for the wire, a fourth liquid injection port for the first expansion balloon and a third liquid injection port for the second expansion balloon, and the rear hole sealer expansion capsule is connected in series with the front hole sealer expansion capsule.

[0007] Further, the composite connector includes a card table, an external thread connection end and a high-pressure joint connection end, and the external thread connection end and the high-pressure joint connection end are respectively assembled at both ends of the card table, a through hexagonal fluid channel is opened inside the card table, the external thread connection end is provided with a connector external thread, the high-pressure joint connection end is a high-pressure connection male head, and a screwing groove is opened on the outer surface of the card table;

[0008] The connecting ring comprises a semicircular ring and a pressing cover. The two semicircular rings are assembled to form a ring structure. The surface of the semicircular ring is integrally formed with a convex tooth matching the slot of the front hole sealer. The outer surface of the end of the semicircular ring is provided with a concave platform matching the pressing cover. The inner surface of the concave platform is provided with a pin hole. The inner surface of the pressing cover is fixedly installed with a plug matching the pin hole. The outer peripheral surface of the plug is provided with barbs.

[0009] The high-pressure connector includes a high-pressure hose and a high-pressure connecting female head, and the high-pressure connecting female head matches the high-pressure connecting male head. The two high-pressure connecting female heads are assembled at both ends of the high-pressure hose. The outer end of the high-pressure connecting female head is integrally formed with a card tooth matching the screwing card slot. After the composite connecting head is connected to the high-pressure connector, it is placed in the connecting ring.

[0010] Furthermore, the hydraulic fracturing pipe comprises a fracturing pipe shell, a second expansion balloon, a fracturing pipe frame, a fracturing pipe cone and a fracturing pipe boss, and the fracturing pipe frame, the fracturing pipe boss and the fracturing pipe cone have the same structure as the front hole sealer frame, the front hole sealer boss and the front hole sealer cone. The fracturing pipe shell is assembled on the outside of the fracturing pipe frame, and both ends of the fracturing pipe frame are equipped with fracturing pipe cones. Two fracturing pipe bosses are assembled on the outer ends of two fracturing pipe cones. The outer ends of the two fracturing pipe cones are provided with a second injection port of the expansion capsule and a second injection port of the first expansion balloon. The outer end of one of the fracturing pipe cones is provided with a second expansion balloon. A first liquid injection port for an expansion balloon, a first liquid injection channel for an expansion capsule connected to a second liquid injection port for the expansion capsule and a first liquid injection channel for a first expansion balloon connected to the second liquid injection port for the first expansion balloon are arranged between the two fracturing tube cones, a second expansion balloon connecting tube connected to the first liquid injection port for the second expansion balloon is fixedly mounted on the inner end of one of the fracturing tube cones, and the second expansion balloon is arranged on the inner end of the second expansion balloon connecting tube, a second balloon chamber is arranged between the fracturing tube shell and the fracturing tube skeleton, and the second expansion balloon is located in the second balloon chamber, a liquid outlet is arranged on the surface of the fracturing tube shell, and a plug is arranged in the liquid outlet.

[0011] Further, the liquid CO2 phase change fracturing tube comprises a fracturing tube frame, a fracturing tube shell, a fracturing tube boss, a fracturing tube cone and a spiral heating tube, and the fracturing tube frame, the fracturing tube boss and the fracturing tube cone have the same structure as the front hole sealer frame, the front hole sealer boss and the front hole sealer cone, the fracturing tube shell is mounted on the outside of the fracturing tube frame, both ends of the fracturing tube frame are equipped with fracturing tube cones, two of the fracturing tube bosses are mounted on the outer ends of two of the fracturing tube cones, a liquid CO2 storage chamber is provided between the fracturing tube shell and the fracturing tube frame, the outer ends of the two fracturing tube cones are provided with a third liquid injection port of a first expansion balloon, a second liquid injection port of a second expansion balloon and a third liquid injection port of an expansion capsule, and a liquid injection port connected to the third liquid injection port of the expansion capsule is provided between the two fracturing tube cones. The second liquid injection channel of the expansion capsule connected to the first expansion balloon, the second liquid injection channel of the first expansion balloon connected to the third liquid injection port of the first expansion balloon, the first liquid injection channel of the second expansion balloon connected to the second liquid injection port of the second expansion balloon, a heating tube connection port is provided at the outer end of the fracturing tube cone, a spiral heating tube is spirally wound in the liquid CO2 storage chamber, and the spiral heating tube is connected to the heating tube connection port, a first threaded hole and an energy release port are respectively provided at both ends of the surface of the fracturing tube shell, a liquid CO2 injection valve is installed in the first threaded hole, a second threaded hole is provided in the energy release port, a constant pressure energy release plate is installed in the second threaded hole, a hexagonal energy release port is installed on the constant pressure energy release plate, and the heating tube connection port is connected to the first connection port of the wire through a wire connector;

[0012] The wire connector includes a hose, a base and a plug, the two bases are assembled at the two ends of the hose, the plug is fixedly installed on the outer end of the base, the outer circumference of the plug is symmetrically fixed with rectangular wings, the outer surface of the rectangular wings is fixedly installed with conductive protrusions, two wires are arranged inside the hose, and the two ends of the wires are respectively connected to the conductive protrusions on the two plugs.

[0013] The drill rods include a first group of drill rods and common drill rods, the common drill rods are connected to one end of the front hole sealer, and the first group of drill rods are connected to one end of the rear hole sealer;

[0014] A first group of drill rod fluid channels are provided inside the first group of drill rods, and a first group of drill rod external threads and a first group of drill rod internal threads are provided at both ends of the first group of drill rods respectively. A first group of drill rod slots, a second connecting port for a guide wire, a fifth liquid injection port for an expansion capsule, a fifth liquid injection port for a first expansion balloon, and a fourth liquid injection port for a second expansion balloon are provided at both ends of the first group of drill rods. The first group of drill rods are provided inside with a first expansion balloon third liquid injection channel connected to the fifth liquid injection port of the first expansion balloon, a second liquid injection channel of the second expansion balloon connected to the fourth liquid injection port of the second expansion balloon, a third liquid injection channel of the expansion capsule connected to the fifth liquid injection port of the expansion capsule, and a guide wire channel connected to the second connecting port of the guide wire.

[0015] A method for using a combined fracturing device for phase change and hydraulic fracturing of liquid CO2 while drilling is disclosed, which specifically includes the following steps:

[0016] S1, prepare construction equipment, including pre-installation of drilling construction equipment and combined fracturing device;

[0017] S2, drilling construction, including ordinary drilling construction and measure drilling construction. Ordinary drilling construction is carried out using a drilling rig, a drill bit and an ordinary drill rod according to the normal drilling procedure. Ordinary drilling is used as an observation borehole to control the expansion distance of hydraulic fracturing cracks in the measure borehole;

[0018] Measures Drilling construction is carried out according to the following steps:

[0019] A, design of the location of joint fracturing inside the measure borehole;

[0020] B, normal drilling, drilling of measure holes is carried out according to the above position design, the drill bit is installed on the ordinary drill rod, and the initial drilling is completed;

[0021] C, the combined fracturing device is used with drilling. During the drilling process of the ordinary drill pipe, the front sealer, hydraulic fracturing pipe, liquid CO2 phase change fracturing pipe, rear sealer, and the first set of drill pipe are connected in sequence behind it to form the first set of combined fracturing device. Then, during the drilling process, the second set of front sealers, the second set of hydraulic fracturing pipes, the second set of liquid CO2 phase change fracturing pipes, the second set of rear sealers, and the second set of drill pipes are connected in sequence to form the second set of combined fracturing device until the drill bit reaches the designed hole depth;

[0022] S3, conduct combined fracturing on the coal seam, firstly, at the first group of combined fracturing devices, the liquid CO2 phase change fracturing tube is used to damage the coal wall to form cracks, and then high-pressure hydraulic fracturing is performed through the hydraulic fracturing tube, and the cracks are expanded along the cracks until water flow occurs in the observation borehole;

[0023] Then, the second group of liquid CO2 phase change fracturing tubes are used at the second group of combined fracturing devices to damage the coal wall and form cracks. Then, high-pressure hydraulic fracturing is carried out through the second group of hydraulic fracturing tubes, and the fracturing is expanded along the cracks until water flow appears in the observation borehole.

[0024] Finally, the whole combined fracturing device is depressurized;

[0025] S4, the combined fracturing device is recovered. When the entire combined fracturing device is withdrawn from the measure borehole, the connecting ring, high-voltage connector and wire connector need to be removed first, and then the drilling rig is used to disassemble each pipe according to the normal procedure for disassembling the drill pipe. This cycle is repeated until the entire combined fracturing device is completely taken out.

[0026] Furthermore, in step S2, the specific steps of the combined fracturing device while drilling are:

[0027] First, use the drilling rig to connect the front hole sealer to the rear of the ordinary drill pipe according to the normal procedure of connecting the drill pipe, and then continue drilling;

[0028] When the front hole sealer enters the measure borehole, the drilling rig is used behind it to connect the external thread of the hydraulic fracturing pipe with the internal thread of the front hole sealer of the front hole sealer according to the normal procedure of connecting the drill pipe. After the connection is completed, the construction personnel use the external thread connection end of the composite connector to connect with the first injection port of the expansion capsule and the first injection port of the first expansion balloon at the rear end of the front hole sealer, and the high-pressure connector connection end of the composite connector is connected with the high-pressure connector. When connecting, a sealing ring is installed on the high-pressure connection male head of the composite connector, and the high-pressure connection female head of the high-pressure connector is screwed so that the clamping teeth on the high-pressure connection female head are clamped by the screwing clamping groove of the composite connector, and then the two semicircular rings of the connecting ring are installed to the rear end of the front hole sealer and the front end of the hydraulic fracturing pipe, so that the convex teeth are clamped in the clamping groove, and the two semicircular rings are connected as a whole by pressing the cover;

[0029] Continue drilling, connect the liquid CO2 phase change fracturing pipe to the rear end of the hydraulic fracturing pipe, and install the composite connector, high pressure connector and connecting ring between the two pipes according to the above method;

[0030] Continue drilling, connect the rear end of the liquid CO2 phase change fracturing pipe with the rear hole sealer, and install the composite connector, high-voltage connector, wire connector and connecting ring between the two pipes according to the above method. When installing the wire connector, align the rectangular wing on the plug with the position of the heating pipe connection port, and complete the installation by plugging.

[0031] Continue drilling, connect the first set of drill pipes to the rear end of the rear hole sealer, and install a composite connector, a high-voltage connector, a wire connector and a connecting ring between the rear end of the rear hole sealer and the front end of the first set of drill pipes according to the above method;

[0032] Continue drilling, and install the second set of front sealers, the second set of hydraulic fracturing pipes, the second set of liquid CO2 phase change fracturing pipes, the second set of rear sealers and the second set of drill pipes in sequence at the rear end of the first set of drill pipes according to the above method until the designed hole depth is reached.

[0033] Furthermore, in step S3, the specific steps of performing combined fracturing on the coal seam are:

[0034] When the measure drilling construction is in place, the expansion capsule injection port and the expansion balloon injection port at the rear end of the second group of drill pipes at the orifice of the measure drilling hole are connected to the manual high-pressure injection pump respectively, and the four expansion capsules in the combined fracturing device, the two expansion balloons in the first group, and the expansion balloons of the second group of hydraulic fracturing pipes are injected with liquid. When the internal pressures reach 15MPa, the injection is stopped. At this time, the expansion capsules expand to achieve the sealing function, and the plugs on the hydraulic fracturing pipe and the second group of hydraulic fracturing pipes will be pushed open. At the same time, the first expansion balloon in the front sealer expands to block the fluid channel inside the entire combined fracturing device;

[0035] A detonator is connected to the first wire interface at the rear end of the second group of drill pipes at the orifice of the measure borehole, and the spiral heating tube in the liquid CO2 phase change fracturing tube is heated by the detonator to make the liquid CO2 in the liquid CO2 storage chamber undergo a phase change. When the internal pressure exceeds the breaking pressure of the constant pressure energy release plate, the constant pressure energy release plate is broken, and the high-pressure CO2 gas impacts the coal body, causing damage to the coal wall on one side of the energy release port to form cracks, and the energy release port faces the direction of the observation borehole;

[0036] Then, the high-pressure emulsion pump is connected to the combined fracturing device, and the second expansion balloon in the hydraulic fracturing pipe is depressurized. At this time, the outlet on the hydraulic fracturing pipe will be connected to the fluid channel inside it, and high-pressure hydraulic fracturing is performed in the measure borehole through the high-pressure emulsion pump. The high-pressure fluid will enter the borehole section blocked by the front sealer and the rear sealer through the internal fluid channel of the combined fracturing device and the outlet of the hydraulic fracturing pipe. Under continuous pressurization conditions, the high-pressure fluid will expand along the cracks formed by the liquid CO2 phase change fracturing until water flows in the observation borehole, indicating that the hydraulic fracture has expanded to the observation borehole next to the measure borehole;

[0037] Stop hydraulic fracturing, and depressurize the fluid channel inside the combined fracturing device. Then, inject high-pressure water to 15MPa into the expansion balloon inside the second group of front sealers. At the same time, depressurize the two expansion balloons in the first group. Then, connect the detonator to the second wire interface at the rear end of the second group of drill pipes at the orifice of the measure borehole. Use the detonator to make the liquid CO2 in the second group of liquid CO2 phase change fracturing tubes change phase, thereby damaging the coal wall and forming cracks.

[0038] The expansion balloon in the second group of hydraulic fracturing pipes is depressurized. At this time, the liquid outlet on the second group of hydraulic fracturing pipes will be connected to the fluid channel inside it, and the high-pressure emulsion pump is connected again. High-pressure hydraulic fracturing is performed in the measure borehole through the high-pressure emulsion pump. The high-pressure fluid will pass through the internal fluid channel of the combined fracturing device and the liquid outlet of the second group of hydraulic fracturing pipes into the borehole section blocked by the second group of front sealers and the second group of rear sealers. Under continuous pressurization conditions, the high-pressure fluid will expand along the cracks formed by the liquid CO2 phase change fracturing until water flow appears again in the observation borehole, indicating that the hydraulic cracks at the second group of hydraulic fracturing positions in the measure borehole have expanded to the observation borehole next to the measure borehole.

[0039] Furthermore, in step S4, the specific steps of removing the connecting ring, the high-voltage connector and the wire connector are:

[0040] Before disassembling the adjacent pipes of the combined fracturing device, first use a flat-blade screwdriver to pry out the push covers on the two semicircular rings between the two pipes, then pry off the two semicircular rings, and then remove the high-voltage connector and wire connector connected between the two pipes in turn. The high-voltage connector needs to be pressed and twisted before being removed, and the wire connector can be directly unplugged.

[0041] The beneficial effects of using the present invention are:

[0042] The present invention designs a device for combined liquid CO2 phase change and hydraulic fracturing while drilling. The sealing unit and the additional injection unit can be installed on the drill pipe and connected to each other through a connecting unit, thereby realizing the work while drilling. During the construction of the measure drilling, the additional injection unit can be transported to the combined fracturing position. When the drilling is completed, the liquid CO2 phase change and hydraulic fracturing work can be carried out, thereby reducing the overall construction process and improving the fracturing work efficiency.

[0043] The present invention arranges the hydraulic fracturing pipe and the liquid CO2 phase change fracturing pipe between the front sealer and the rear sealer. After the sealing work is completed, the liquid CO2 phase change and hydraulic fracturing combined fracturing can be achieved, the fracturing effect is improved, and it is effectively applicable to coal seams with low permeability, which is beneficial to the safe production of coal seams.

[0044] The present invention can deploy one or more sets of sealing units and additional units during the drilling process, and further during the measure drilling construction process, the sealing units and additional units can be installed on the drill rod according to the position design of the combined fracturing to realize the segmented combined fracturing work.

[0045] The combined fracturing device of the present invention has a high degree of modularization, each structure is easy to manufacture and simple to operate, can be recycled for many times, and effectively reduces the overall coal seam permeability enhancement cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 It is a three-dimensional schematic diagram of the front hole sealer of the present invention.

[0047] Figure 2 It is a three-dimensional schematic diagram of the front hole sealer after removing the expansion capsule of the front hole sealer according to the present invention.

[0048] Figure 3 This is a three-dimensional schematic diagram of the internal structure of the first balloon chamber of the front hole sealer of the present invention after the cover plate is removed.

[0049] Figure 4 For the present invention Figure 2 Cross-section view along the AA direction.

[0050] Figure 5 The figure is a schematic diagram of the distribution of the card slots of the front hole sealer of the present invention.

[0051] Figure 6 It is a three-dimensional schematic diagram of the composite connector of the present invention.

[0052] Figure 7 It is a schematic structural diagram of the screwing slot of the composite connector of the present invention.

[0053] Figure 8 It is a three-dimensional schematic diagram of the semicircular ring in the connecting ring of the present invention.

[0054] Fig. 9 It is a three-dimensional schematic diagram of the push cover in the connecting ring of the present invention.

[0055] Fig.10 It is a three-dimensional schematic diagram of the high-voltage connector of the present invention.

[0056] Fig.11 It is a three-dimensional schematic diagram of the wire connector of the present invention.

[0057] Fig.12 It is a three-dimensional schematic diagram of the hydraulic fracturing pipe of the present invention.

[0058] Fig.13 It is a schematic internal stereoscopic diagram of the hydraulic fracturing pipe of the present invention.

[0059] Fig.14 This is one of the three-dimensional schematic diagrams of the liquid CO2 phase change fracturing tube of the present invention.

[0060] Fig.15 This is the second stereoscopic schematic diagram of the liquid CO2 phase change fracturing tube of the present invention.

[0061] Fig.16 For the present invention Fig.14 Cross-section along the BB direction.

[0062] Fig.17 It is a schematic internal stereoscopic diagram of the liquid CO2 phase change fracturing tube of the present invention.

[0063] Fig.18 It is a three-dimensional schematic diagram of the rear hole sealer of the present invention.

[0064] Fig.19 It is a three-dimensional schematic diagram of the first set of drill rods of the present invention.

[0065] Fig. 20 For the present invention Fig.19 Cross-sectional view along CC direction.

[0066] Fig.21 It is a three-dimensional schematic diagram of the second set of drill rods of the present invention.

[0067] Fig. 22 For the present invention Fig.21 Cross-sectional view along the DD direction.

[0068] Fig.23 It is a schematic diagram of the arrangement of the drilling holes and observation drilling holes of the present invention.

[0069] Reference numerals include:

[0070] 1. front hole sealer, 1001. front hole sealer expansion capsule, 1002. front hole sealer external thread, 1003. front hole sealer internal thread, 1004. front hole sealer fluid channel, 1005. front hole sealer card slot, 1006. expansion capsule first liquid injection port, 1007. first expansion balloon first liquid injection port, 1008. front hole sealer boss, 1009. front hole sealer frame, 1010. front hole sealer fixing platform, 1011. first balloon chamber, 1012. first expansion balloon, 1013. first expansion balloon connecting tube, 1014. internal liquid injection port of expansion capsule;

[0071] 2. Composite connector, 2001, hexagonal fluid channel, 2002, screw slot, 2003, connector external thread, 2004, high pressure connector male, 2005, card table;

[0072] 3. Connecting ring, 3001, semicircular ring, 3002, convex teeth, 3003, pin hole, 3004, concave platform, 3005, latch, 3006, press cover, 3007, barb;

[0073] 4. High-pressure connector, 4001, high-pressure hose, 4002, latch, 4003, high-pressure female connector;

[0074] 5. Wire connector, 5001, hose, 5002, base, 5003, plug, 5004, rectangular wing, 5005, conductive protrusion;

[0075] 6. Hydraulic fracturing pipe, 6001. External thread of fracturing pipe, 6002. Internal thread of fracturing pipe, 6003. Second injection port of expansion capsule, 6004. Slot of fracturing pipe, 6005. Second injection port of first expansion balloon, 6006. First injection port of second expansion balloon, 6007. Connecting pipe of second expansion balloon, 6008. Second expansion balloon, 6009. Second balloon chamber, 6010. Liquid outlet, 6011. Fracturing pipe frame, 6012. First injection channel of expansion capsule, 6013. First injection channel of first expansion balloon, 6014. Plug;

[0076] 7. Liquid CO2 phase change fracturing tube, 7001. Fracturing tube fluid channel, 7002. Fracturing tube external thread, 7003. Third injection port of first expansion balloon, 7004. Second injection port of second expansion balloon, 7005. Third injection port of expansion capsule, 7006. Second injection channel of expansion capsule, 7007. Second injection channel of first expansion balloon, 7008. Spiral heating tube, 7009. Fracturing tube slot, 7010. Fracturing tube internal thread, 7011. Heating tube connection port, 7012. Liquid CO2 storage chamber, 7013. First threaded hole, 7014. Liquid CO2 injection valve, 7015. Constant pressure energy release sheet, 7016. Hexagonal energy release port, 7017. Second threaded hole, 7018. Energy release port, 7019. First injection channel of second expansion balloon;

[0077] 8. rear hole sealer, 8001. rear hole sealer fluid channel, 8002. rear hole sealer internal thread, 8003. fourth liquid injection port of expansion capsule, 8004. first connection port of wire, 8005. rear hole sealer card slot, 8006. fourth liquid injection port of first expansion balloon, 8007. third liquid injection port of second expansion balloon, 8008. rear hole sealer expansion capsule, 8009. rear hole sealer external thread, 8010. rear hole sealer boss;

[0078] 9. The first set of drill rods, 9001. The first set of drill rod fluid channels, 9002. The first set of drill rod external threads, 9003. The first set of drill rod slots, 9004. The second connection port for the wire, 9005. The fifth injection port for the expansion capsule, 9006. The fifth injection port for the first expansion balloon, 9007. The fourth injection port for the second expansion balloon, 9008. The third injection channel for the first expansion balloon, 9009. The second injection channel for the second expansion balloon, 9010. The third injection channel for the expansion capsule, 9011. The wire channel;

[0079] 10. The second group of drill rods, 10001. The second group of drill rod external threads, 10002. The second group of drill rod fluid channels, 10003. The sixth injection port of the expansion capsule, 10004. The first wire interface, 10005. The second wire interface, 10006. The sixth injection port of the first expansion balloon, 10007. The fifth injection port of the second expansion balloon, 10008. The third injection port of the expansion balloon, 10009. The fourth injection port of the expansion balloon, 10010. The fourth injection channel of the expansion capsule, 10011. The first wire channel, 10012. The second wire channel, 10013. The fourth injection channel of the first expansion balloon, 10014. The third injection channel of the second expansion balloon, 10015. The injection channel of the third expansion balloon, 10016. The injection channel of the fourth expansion balloon, 10017. The second group of drill rod slots;

[0080] 11. Return air lane of coal mining working face, 12. Air inlet lane of coal mining working face, 13. Measure drilling hole, 14. Observation drilling hole, 15. Second group of front hole sealers, 16. Second group of hydraulic fracturing pipes, 17. Second group of liquid CO2 phase change fracturing pipes, 18. Second group of rear hole sealers, 19. Drill bit, 20. Ordinary drill pipe. DETAILED DESCRIPTION

[0081] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0082] Embodiment 1

[0083] Reference Figures 1 to 22 A combined fracturing device for phase change and hydraulic fracturing of liquid CO2 during drilling, comprising a sealing unit, a connecting unit and an additional unit, wherein the sealing unit comprises a front sealing device 1 and a rear sealing device 8, the connecting unit comprises a composite connector 2, a connecting ring 3, a high-pressure connector 4, a wire connector 5 and a drill pipe, the additional unit comprises a hydraulic fracturing pipe 6 and a liquid CO2 phase change fracturing pipe 7, the front sealing device 1 and the rear sealing device 8 are assembled at one end of different drill pipes, and the hydraulic fracturing pipe 6 and the liquid CO2 phase change fracturing pipe 7 ... The fracturing tube 7 is installed between the front sealer 1 and the rear sealer 8. The front sealer 1, the hydraulic fracturing tube 6, the liquid CO2 phase change fracturing tube 7, and the rear sealer 8 are connected by a connecting ring 3. The composite connector 2 is installed at the front sealer 1, the hydraulic fracturing tube 6, the liquid CO2 phase change fracturing tube 7, the rear sealer 8, and the end of the drill pipe, and the composite connectors 2 are connected by a high-pressure connector 4. A wire connector 5 is provided between the liquid CO2 phase change fracturing tube 7 and the rear sealer 8.

[0084] The hydraulic fracturing tube 6 and the liquid CO2 phase change fracturing tube 7 are located between the front sealer 1 and the rear sealer 8, and the front sealer 1 and the rear sealer 8 are respectively installed at one end of different drill pipes. After being connected to each other, the front sealer 1, the hydraulic fracturing tube 6, the liquid CO2 phase change fracturing tube 7 and the rear sealer 8 can be installed on the drill pipe to achieve movement while drilling. The sealing unit and the additional unit can be set up while the construction of the measure borehole 13 is completed. After that, the liquid CO2 phase change and hydraulic fracturing combined fracturing can be carried out directly. Compared with the traditional method of repeatedly putting in and taking out the liquid CO2 phase change fracturing tube 7 and the hydraulic fracturing tube 6 in the measure borehole 13, the overall construction process is reduced and the fracturing work efficiency is improved.

[0085] During the construction of the measure drilling 13, multiple sets of sealing units and additional units can be connected to the drill pipe to achieve multiple releases in one drilling, and the measure drilling 13 can be completed for segmented joint fracturing to further improve the fracturing work efficiency.

[0086] Specifically, if Figures 1 to 5 As shown, the front hole sealer 1 includes a front hole sealer expansion capsule 1001, a front hole sealer boss 1008, a front hole sealer frame 1009, a front hole sealer fixing platform 1010, a first expansion balloon 1012 and a first expansion balloon connecting tube 1013, the front hole sealer frame 1009 has front hole sealer truncated cones formed integrally at both ends, the front hole sealer expansion capsule 1001 is wrapped between the outside of the front hole sealer frame 1009 and the two front hole sealer truncated cones, the two front hole sealer bosses 1008 are respectively assembled at the outer ends of the two front hole sealer truncated cones, the front hole sealer frame 1009 has a through front hole sealer fluid channel 1004, the outer surface of one front hole sealer boss 1008 has a front hole sealer external thread 1002, and the inner surface of the other front hole sealer boss 1008 has a front hole sealer internal thread 1003, a front hole sealer truncated cone is provided with a front hole sealer slot 1005, a first liquid injection port 1006 for the expansion capsule and a first liquid injection port 1007 for the first expansion balloon on its outer surface, a front hole sealer fixing platform 1010 is fixedly installed on the inner end of the front hole sealer truncated cone, an inner end of the front hole sealer fixing platform 1010 is provided with an internal liquid injection port 1014 for the expansion capsule communicating with the first liquid injection port 1006 for the expansion capsule and a first expansion balloon connecting tube 1013 communicating with the first liquid injection port 1007 for the first expansion balloon, a first expansion balloon 1012 is assembled on the inner end of the first expansion balloon connecting tube 1013, a first balloon chamber 1011 communicating with the front hole sealer fluid channel 1004 is provided on the outer surface of the front hole sealer skeleton 1009, and the first expansion balloon 1012 is located in the first balloon chamber 1011.

[0087] The front hole sealer expansion capsule 1001 is made of rubber material and can expand when filled with high-pressure gas or liquid. The maximum pressure resistance value is 30MPa. It is wrapped around the outside of the front hole sealer and covers 70% to 80% of the entire surface area of ​​the front hole sealer. The cross-sectional diameter of the front hole sealer 1 part coated with the front hole sealer expansion capsule 1001 is 3 to 8mm smaller than the cross-sectional diameter of the uncoated section, and the protruding part is the front hole sealer cone.

[0088] The front hole sealer slot 1005 is arranged at the outer end of a front hole sealer truncated cone, and six front hole sealer slots 1005 are arranged on the front hole sealer truncated cone. Figure 5 The figure shows the distribution of the front hole sealer slots 1005 on the front hole sealer cone. The front hole sealer slots 1005 are arranged at eight equal parts of the outer end surface of the front hole sealer cone, and the front hole sealer slots 1005 are symmetrically distributed, three on each side, and the front hole sealer slots 1005 are in the shape of a cube.

[0089] The distribution of the fracturing tube slot 6004 on the hydraulic fracturing tube 6, the fracturing tube slot 7009 on the liquid CO2 phase change fracturing tube 7, the rear sealer slot 8005, the first group of drill pipe slots 9003 and the second group of drill pipe slots 10017 are the same as the shape and distribution of the front sealer slot 1005.

[0090] The first liquid injection port 1006 of the expansion capsule is arranged at the outer end of a front hole sealer cone on the front hole sealer 1, and is provided with an internal thread inside for connecting with the composite connector.

[0091] The first liquid injection port 1007 of the first expansion balloon is arranged at the outer end of a front hole sealer cone on the front hole sealer 1, and the angle between it and the first liquid injection port 1006 of the expansion capsule is 30°~40°, and its center is cocircular with the center of the first liquid injection port 1006 of the expansion capsule, and the center of this circle is located on the axis of the front hole sealer skeleton 1009.

[0092] The front hole sealer boss 1008 is a metal product in a cylindrical shape. Its axial length along the front hole sealer 1 is 10 to 20 cm, and its radius is 1 / 3 to 1 / 2 of the maximum radius of the front hole sealer skeleton 1009. The lengths of the front hole sealer external thread 1002 and the front hole sealer internal thread 1003 opened on the surface of the front hole sealer boss 1008 are both half the length of the front hole sealer boss 1008, i.e., 5 to 10 cm.

[0093] The front hole sealer frame 1009 is made of metal and is used to support the structure on the front hole sealer 1 .

[0094] The front hole sealer fixing platform 1010 is made of metal, is located at both ends of the front hole sealer expansion capsule 1001 and is connected to the front hole sealer frame 1009 , and is used to install and fix the front hole sealer expansion capsule 1001 .

[0095] The end face of the first balloon chamber 1011 is rectangular, and is used to store the first expansion balloon 1012. Its cross-sectional area is not less than twice the cross-sectional area of ​​the front sealer fluid channel 1004, so as to increase the flow space of the fluid in this section of the fluid channel and minimize the obstruction of the balloon body thereto. A cover plate is installed at the end of the first balloon chamber 1011, which is used to separate the space inside the front sealer expansion capsule 1001 from the space inside the first balloon chamber 1011.

[0096] The first expansion balloon 1012 is made of rubber and can expand after being injected with high-pressure fluid. When not expanded, the maximum cross-sectional area of ​​the balloon body covering the front sealer fluid channel 1004 does not exceed 20%, so as to reduce the flow resistance of the fluid in the front sealer fluid channel 1004.

[0097] The first expansion balloon connecting tube 1013 is made of metal, is hollow inside, and is L-shaped, and is used to connect the first expansion balloon 1012 and the first expansion balloon first injection port 1007 .

[0098] The internal liquid injection port 1014 of the expansion capsule is communicated with the first liquid injection port 1006 of the expansion capsule, and is used to inject high-pressure fluid into the space between the front hole sealer expansion capsule 1001 and the front hole sealer frame 1009 .

[0099] One end of the front hole sealer 1 having the front hole sealer slot 1005 is connected to the hydraulic fracturing pipe 6 , while the other end is not provided with the front hole sealer slot 1005 , the first liquid injection port 1006 of the expansion capsule and the first liquid injection port 1007 of the first expansion balloon, and is used to be connected to the ordinary drill pipe 20 .

[0100] like Fig.18 As shown, the rear hole sealer 8 includes a rear hole sealer frame, a rear hole sealer expansion capsule 8008, a rear hole sealer boss 8010, a rear hole sealer fixing platform and a rear hole sealer round platform, and the rear hole sealer frame, the rear hole sealer expansion capsule 8008, the rear hole sealer boss 8010, the rear hole sealer fixing platform, and the rear hole sealer round platform have the same structure as the front hole sealer frame 1009, the front hole sealer expansion capsule 1001, the front hole sealer boss 1008, the front hole sealer fixing platform 1010, and the front hole sealer round platform, and both ends of the rear hole sealer frame are equipped with rear hole sealer round platforms. The two rear hole sealer bosses 8010 are assembled on the outer ends of the two rear hole sealer truncated cones, the two rear hole sealer fixing platforms are assembled on the inner ends of the two rear hole sealer truncated cones, the rear hole sealer expansion capsule 8008 is wrapped on the outside of the rear hole sealer frame, the outer ends of the two rear hole sealer truncated cones are provided with the fourth liquid injection port 8003 of the expansion capsule, the first connecting port 8004 of the wire, the fourth liquid injection port 8006 of the first expansion balloon and the third liquid injection port 8007 of the second expansion balloon, and the rear hole sealer expansion capsule 8008 is connected in series with the front hole sealer expansion capsule 1001.

[0101] A rear hole sealer fluid channel 8001 is arranged inside the rear hole sealer frame, and rear hole sealer internal threads 8002 and rear hole sealer external threads 8009 are arranged on two rear hole sealer bosses 8010 respectively, and rear hole sealer slots 8005 are arranged on both rear hole sealer convex platforms.

[0102] The rear hole sealer 8 is different from the front hole sealer 1 mainly in that no balloon is arranged inside the rear hole sealer 8 .

[0103] Since the rear sealer expansion capsule 8008 is connected in series with the front sealer expansion capsule 1001, during the liquid injection expansion and pressure relief process, the internal pressure of the rear sealer expansion capsule 8008 and the front sealer expansion capsule 1001 is the same, and they expand or relieve pressure at the same time.

[0104] In the case of providing a second group of front sealers 15, a second group of hydraulic fracturing tubes 16, a second group of liquid CO2 phase change fracturing tubes 17 and a second group of rear sealers 18, or providing multiple groups of sealing units and additional units, the expansion capsules on all sealers are connected in series, and are simultaneously injected with liquid for expansion and pressure relief.

[0105] Specifically, if Figure 6 and Figure 7 As shown, the composite connector 2 includes a base 2005, an externally threaded connection end and a high-pressure joint connection end, and the externally threaded connection end and the high-pressure joint connection end are respectively assembled at the two ends of the base 2005, a through hexagonal fluid channel 2001 is opened inside the base 2005, the externally threaded connection end is provided with a connector external thread 2003, the high-pressure joint connection end is a high-pressure connection male head 2004, and a screwing groove 2002 is opened on the outer surface of the base 2005.

[0106] The composite connector 2 is made of metal and has a hollow structure inside. The internal shape of the high-voltage connector 2004 is hexagonal, which is convenient for screwing it with a corresponding screwdriver.

[0107] like Figure 7 As shown, the structure of the screw slot 2002 can be known. The inside of the screw slot 2002 is provided with a groove toward the side. The latch tooth 4002 on the high-voltage connector 4 can be inserted into the screw slot 2002. After the high-voltage connector 4 is rotated, the latch tooth 4002 will move into the groove in the screw slot 2002, thereby completing the connection between the high-voltage connector 4 and the composite connector 2.

[0108] like Figure 8 and Fig. 9As shown, the connecting ring 3 includes a semicircular ring 3001 and a pressing cover 3006. The two semicircular rings 3001 are assembled to form an annular structure. The surface of the semicircular ring 3001 is integrally formed with a convex tooth 3002 that matches the front hole sealer slot 1005. The outer surface of the end of the semicircular ring 3001 is provided with a concave platform 3004 that matches the pressing cover 3006. The inner surface of the concave platform 3004 is provided with a pin hole 3003. The inner surface of the pressing cover 3006 is fixedly installed with a plug 3005 that matches the pin hole 3003, and the outer peripheral surface of the plug 3005 is provided with a barb 3007.

[0109] The connecting ring 3 is made of wear-resistant and flame-retardant PVC material.

[0110] The thickness of the semicircular ring 3001 is 2 to 5 cm. Three convex teeth 3002 are arranged on the two side planes of the semicircular ring 3001, corresponding to the front hole sealer slot 1005 on the front hole sealer 1. The connection between two adjacent pipelines is realized through the connecting ring 3, and the composite connector 2, the high-voltage connector 4, and the wire connector 5 are located in the connecting ring 3.

[0111] After the two semicircular rings 3001 are assembled, the concave platforms 3004 will be assembled to form a rectangular cavity, which matches the press cover 3006. Two pin holes 3003 are symmetrically arranged on each concave platform 3004, and the depth of the pin holes 3003 is 1 / 2 to 2 / 3 of the thickness of the semicircular ring 3001.

[0112] The outer side of the cover 3006 is arc-shaped, matching the outer arc of the semicircular ring 3001 , and four latches 3005 are arranged on the inner side. The barbs 3007 on the latches 3005 increase the stability and firmness of the latches 3005 when inserted into the pin holes 3003 .

[0113] like Fig.10 As shown, the high-pressure connector 4 includes a high-pressure hose 4001 and a high-pressure connecting female head 4003, and the high-pressure connecting female head 4003 matches the high-pressure connecting male head 2004. The two high-pressure connecting female heads 4003 are assembled at both ends of the high-pressure hose 4001. The outer end of the high-pressure connecting female head 4003 is integrally formed with a latch tooth 4002 that matches the screwing slot 2002. After the composite connector 2 is connected to the high-pressure connector 4, it is placed in the connecting ring 3.

[0114] Specifically, if Fig.12 and Fig.13As shown, the hydraulic fracturing pipe 6 includes a fracturing pipe shell, a second expansion balloon 6008, a fracturing pipe frame 6011, a fracturing pipe cone and a fracturing pipe boss, and the fracturing pipe frame 6011, the fracturing pipe boss and the fracturing pipe cone have the same structure as the front hole sealer frame 1009, the front hole sealer boss 1008 and the front hole sealer cone. The fracturing pipe shell is assembled on the outside of the fracturing pipe frame 6011, and both ends of the fracturing pipe frame 6011 are equipped with fracturing pipe cones. Two fracturing pipe bosses are assembled on the outer ends of two fracturing pipe cones. The outer ends of the two fracturing pipe cones are provided with a second injection port 6003 of the expansion capsule and a second injection port 6005 of the first expansion balloon. The outer end of one fracturing pipe cone is provided with a first injection port 6006 of the second expansion balloon. The first liquid injection channel 6012 of the expansion capsule connected to the second liquid injection port 6003 of the expansion capsule and the first liquid injection channel 6013 of the first expansion balloon connected to the second liquid injection port 6005 of the first expansion balloon are arranged between the tube cones; the inner end of a fracturing tube cone is fixedly installed with a second expansion balloon connecting tube 6007 connected to the first liquid injection port 6006 of the second expansion balloon, and the second expansion balloon 6008 is arranged on the inner end of the second expansion balloon connecting tube 6007; a second balloon chamber 6009 is arranged between the fracturing tube shell and the fracturing tube skeleton 6011, and the second expansion balloon 6008 is located in the second balloon chamber 6009; a liquid outlet 6010 is opened on the surface of the fracturing tube shell, and a plug 6014 is arranged in the liquid outlet 6010.

[0115] The fracturing pipe bosses at both ends are respectively provided with fracturing pipe external threads 6001 and fracturing pipe internal threads 6002, and the fracturing pipe circular platform is provided with a fracturing pipe clamping groove 6004.

[0116] The second balloon chamber 6009 is in a cubic shape, the bottom of the balloon chamber is connected to the fluid channel of the fracturing tube, and the top of the second balloon chamber 6009 is connected to the liquid outlet 6010, that is, the second expansion balloon 6008 in the second balloon chamber 6009 can control whether the fluid in the fluid channel can pass through the liquid outlet 6010 by expanding and contracting.

[0117] When the fluid pressure in the fluid channel exceeds 5 MPa or the inflation pressure of the second inflation balloon 6008 in the second balloon chamber 6009 reaches 5 MPa, the plug 6014 will be pushed open.

[0118] Specifically, if Figures 14 to 17As shown, the liquid CO2 phase change fracturing tube 7 includes a fracturing tube frame, a fracturing tube shell, a fracturing tube boss, a fracturing tube cone and a spiral heating tube 7008, and the fracturing tube frame, the fracturing tube boss, the fracturing tube cone and the front hole sealer frame 1009, the front hole sealer boss 1008, and the front hole sealer cone have the same structure. The fracturing tube shell is assembled on the outside of the fracturing tube frame, and the two ends of the fracturing tube frame are equipped with fracturing tube cones. The two fracturing tube bosses are assembled on the two The outer end of the fracturing tube truncated cone, the liquid CO2 storage chamber 7012 is between the fracturing tube shell and the fracturing tube frame, the outer ends of the two fracturing tube truncated cones are provided with a first expansion balloon third liquid injection port 7003, a second expansion balloon second liquid injection port 7004 and an expansion capsule third liquid injection port 7005, and between the two fracturing tube truncated cones is provided an expansion capsule second liquid injection channel 7006 connected to the expansion capsule third liquid injection port 7005, and a first expansion balloon third liquid injection port 7007 connected to the first expansion balloon third liquid injection port 7008. A second liquid injection channel 7007 of the first expansion balloon connected to the port 7003, a first liquid injection channel 7019 of the second expansion balloon connected to the second liquid injection port 7004 of the second expansion balloon, a heating tube connecting port 7011 is provided at the outer end of a fracturing tube cone, a spiral heating tube 7008 is spirally coiled in the liquid CO2 storage chamber 7012, and the spiral heating tube 7008 is connected to the heating tube connecting port 7011, a first threaded hole 7013 and an energy release port 7018 are respectively provided at both ends of the surface of the fracturing tube shell, a liquid CO2 injection valve 7014 is installed in the first threaded hole 7013, a second threaded hole 7017 is provided in the energy release port 7018, a constant pressure energy release plate 7015 is installed in the second threaded hole 7017, a hexagonal energy release port 7016 is installed on the constant pressure energy release plate 7015, and the heating tube connecting port 7011 is connected to the first connecting port 8004 of the wire through a wire connector 5.

[0119] The fracturing tube bosses at both ends are provided with fracturing tube external threads 7002 and fracturing tube internal threads 7010 respectively, and a fracturing tube clamping groove 7009 is provided on the fracturing tube truncated cone. A fracturing tube fluid channel 7001 is provided inside the liquid CO2 phase change fracturing tube 7.

[0120] The spiral heating tube 7008 inside the liquid CO2 phase change fracturing tube 7 is spirally coiled in the liquid CO2 storage chamber 7012, which can heat the liquid CO2 in the liquid CO2 storage chamber 7012 to the maximum extent.

[0121] The diameter of the energy release port 7018 is smaller than the diameter of the second threaded hole 7017, so that the constant pressure energy release plate 7015 can be placed in the second threaded hole 7017. The outer side of the hexagonal energy release port 7016 is provided with threads for installation in the second threaded hole 7017. The hexagonal energy release port 7016 cooperates with the energy release port 7018 to fix the constant pressure energy release plate 7015. The interior of the hexagonal energy release port 7016 is a hexagonal central control structure, which is easy to screw.

[0122] The exterior of the liquid CO 2 injection valve 7014 is provided with threads for installation in the first threaded hole 7013 .

[0123] The liquid CO2 injection valve 7014 and the energy release port 7018 are arranged on both sides of the outer peripheral surface of the fracturing tube shell and are symmetrically distributed. The liquid CO2 injection valve 7014 is close to the side of the internal thread 7010 of the fracturing tube, and the energy release port 7018 is close to the side of the external thread 7002 of the fracturing tube.

[0124] like Fig.11 As shown, the wire connector 5 includes a hose 5001, a base 5002 and a plug 5003, the two bases 5002 are assembled at the two ends of the hose 5001, the plug 5003 is fixedly installed on the outer end of the base 5002, the outer circumference of the plug 5003 is symmetrically fixedly installed with rectangular wings 5004, the outer surface of the rectangular wings 5004 is fixedly installed with conductive protrusions 5005, two wires are arranged inside the hose 5001, and the two ends of the wires are respectively connected to the conductive protrusions 5005 on the two plugs 5003.

[0125] Except for the wires and the conductive protrusions 5005 , the other structures of the wire connector 5 are made of flame-retardant rubber.

[0126] Specifically, the drill rods include a first group of drill rods 9 and a common drill rod 20 . The common drill rod 20 is connected to one end of the front hole sealer 1 , and the first group of drill rods 9 is connected to one end of the rear hole sealer 8 .

[0127] A drill bit 19 is installed at the front end of the common drill rod 20 for carrying out the construction work of the measure drilling hole 13 .

[0128] like Fig.19 and Fig. 20 As shown, the first group of drill rods 9 are provided with a first group of drill rod fluid channels 9001 inside, and the first two ends of the first group of drill rods 9 are provided with a first group of drill rod external threads 9002 and a first group of drill rod internal threads respectively, and the first two ends of the first group of drill rods 9 are provided with a first group of drill rod slots 9003, a second connecting port 9004 for a guide wire, a fifth liquid injection port 9005 for an expansion capsule, a fifth liquid injection port 9006 for a first expansion balloon, and a fourth liquid injection port 9007 for a second expansion balloon, and the first group of drill rods 9 are provided with a third liquid injection channel 9008 for a first expansion balloon connected with the fifth liquid injection port 9006 of the first expansion balloon, a second liquid injection channel 9009 for a second expansion balloon connected with the fourth liquid injection port 9007 of the second expansion balloon, a third liquid injection channel 9010 for an expansion capsule connected with the fifth liquid injection port 9005 of the expansion capsule, and a guide wire channel 9011 connected with the second connecting port 9004 of the guide wire.

[0129] The first group of drill rods 9 are installed at the outer end of the rear hole sealer 8, and multiple first group of drill rods 9 are connected to realize drilling work. The first group of drill rod external threads 9002 and the first group of drill rod internal threads are used to realize the connection between multiple first group of drill rods 9 and to connect other pipe fittings.

[0130] like Fig.21 and Fig. 22 As shown, the drill rod also includes a second group of drill rods 10, the second group of drill rods 10 are provided with a second group of drill rod fluid channels 10002, the second group of drill rod external threads 10001 and the second group of drill rod internal threads are provided at both ends of the second group of drill rods 10, and the second group of drill rods 10 are provided with a sixth liquid injection port 10003 for the expansion capsule, a first wire interface 10004, a second wire interface 10005, a sixth liquid injection port 10006 for the first expansion balloon, and a fifth liquid injection port 10007 for the second expansion balloon. 07, the third expansion balloon injection port 10008, the fourth expansion balloon injection port 10009 and the second group of drill rod slots 10017, the interior of the second group of drill rods 10 is provided with the fourth injection channel 10010 of the expansion capsule, the first wire channel 10011, the second wire channel 10012, the fourth injection channel 10013 of the first expansion balloon, the third injection channel 10014 of the second expansion balloon, the third expansion balloon injection channel 10015, and the fourth expansion balloon injection channel 10016.

[0131] The fourth injection channel 10010 of the expansion capsule is used to connect the sixth injection port 10003 of the expansion capsule at both ends of the second group of drill rods 10, the first wire channel 10011 is used to connect the first wire interface 10004, the second wire channel 10012 is used to connect the second wire interface 10005, the fourth injection channel 10013 of the first expansion balloon is used to connect the sixth injection port 10006 of the first expansion balloon, the third injection channel 10014 of the second expansion balloon is used to connect the fifth injection port 10007 of the second expansion balloon, the third expansion balloon injection channel 10015 is used to connect the third expansion balloon injection port 10008, and the fourth expansion balloon injection channel 10016 is used to connect the fourth expansion balloon injection port 10009.

[0132] When it is necessary to perform segmented combined fracturing in a measure borehole 13, a second group of front sealers 15, a second group of hydraulic fracturing pipes 16, a second group of liquid CO2 phase change fracturing pipes 17 and a second group of rear sealers 18 can be connected in sequence behind the first group of drill pipes 9, and then the second group of drill pipes 10 can be connected to realize the drilling work, wherein the second group of front sealers 15 has the same structure as the front sealer 1, the second group of hydraulic fracturing pipes 16 has the same structure as the hydraulic fracturing pipe 6, the second group of liquid CO2 phase change fracturing pipes 17 has the same structure as the liquid CO2 phase change fracturing pipes 7, and the second group of rear sealers 18 has the same structure as the rear sealer 8. The difference between the above two groups of structures mainly lies in that a newly added injection port and channel need to be set in the structure of the second group.

[0133] In practical applications, multiple groups of front sealers 1, hydraulic fracturing pipes 6, liquid CO2 phase change fracturing pipes 7 and rear sealers 8 can be set in the measure borehole 13, so that multiple groups of combined fracturing devices can be deployed in one drilling operation and multiple stages of combined fracturing work can be completed in the measure borehole 13.

[0134] Embodiment 2

[0135] A method for using a combined liquid CO2 phase change and hydraulic fracturing device while drilling, using the combined liquid CO2 phase change and hydraulic fracturing device while drilling as in Example 1, specifically comprises the following steps:

[0136] S1, prepare construction equipment, including pre-installation of drilling construction equipment and combined fracturing device;

[0137] First, the drilling rig, drill bit 19, common drill pipe 20, and combined fracturing device used in the construction are transported to the underground construction site. The composite connector 2 can be installed with a corresponding screwdriver at the locations of the front hole sealer 1, hydraulic fracturing pipe 6, liquid CO2 phase change fracturing pipe 7, rear hole sealer 8, and the expansion capsule injection port and the expansion balloon injection port on the first set of drill pipes 9 of the combined fracturing device, so that the various pipe fittings can be quickly connected during construction;

[0138] The liquid CO2 phase change fracturing pipe 7 needs to be injected with corresponding liquid CO2, and the liquid outlet 6010 on the hydraulic fracturing pipe 6 needs to be installed with a plug 6014;

[0139] S2, drilling construction, including ordinary drilling construction and measure drilling construction. Ordinary drilling construction is carried out according to normal drilling procedures using a drilling rig, a drill bit 19 and an ordinary drill rod 20. The ordinary borehole is used as an observation borehole 14 to control the expansion distance of the hydraulic fracturing crack in the measure borehole 13;

[0140] Measures Drilling construction is carried out according to the following steps:

[0141] A, the location design of the combined fracturing inside the measure borehole 13;

[0142] In practical applications, multiple fracture locations can be designed in the measure borehole 13;

[0143] In the joint fracturing location design, the distance between adjacent fracturing locations shall not be less than 20m;

[0144] B, normal drilling, drilling the measure borehole 13 according to the above position design, installing the drill bit 19 on the ordinary drill rod 20, and completing the initial drilling;

[0145] C. Combined fracturing device is used with drilling. During the drilling process of the common drill pipe 20, the front sealer 1, the hydraulic fracturing pipe 6, the liquid CO2 phase change fracturing pipe 7, the rear sealer 8, and the first set of drill pipes 9 are sequentially connected behind it to form the first set of combined fracturing device. After that, the second set of front sealers 15, the second set of hydraulic fracturing pipes 16, the second set of liquid CO2 phase change fracturing pipes 17, the second set of rear sealers 18, and the second set of drill pipes 10 are sequentially connected during the drilling process to form the second set of combined fracturing device until the drill bit 19 reaches the designed hole depth;

[0146] The specific steps of the combined fracturing device while drilling are as follows:

[0147] First, use the drilling rig to connect the front hole sealer 1 to the rear of the ordinary drill rod 20 according to the normal procedure of connecting the drill rod, and then continue drilling;

[0148] When the front sealer 1 enters the measure borehole 13, the drilling rig is used behind it to connect the external thread 6001 of the hydraulic fracturing pipe 6 with the internal thread 1003 of the front sealer 1 according to the normal procedure of connecting the drill pipe. After the connection is completed, the construction personnel use the external thread connection end of the composite connector 2 to connect the first injection port 1006 of the expansion capsule and the first injection port 1007 of the first expansion balloon at the rear end of the front sealer 1, and the high-pressure connector connection end of the composite connector 2 is connected to the high-pressure connector 4. When connecting, install a sealing ring on the high-pressure connection male head 2004 of the composite connector 2, and screw the high-pressure connection female head 4003 of the high-pressure connector 4, so that the clamping teeth 4002 on the high-pressure connection female head 4003 are clamped by the screwing clamping groove 2002 of the composite connector 2, and then install the two semicircular rings 3001 of the connecting ring 3 to the rear end of the front hole sealer 1 and the front end of the hydraulic fracturing pipe 6, so that the convex teeth 3002 are clamped in the clamping groove, and the two semicircular rings 3001 are connected as a whole by pressing the cover 3006;

[0149] Continue drilling, connect the liquid CO2 phase change fracturing pipe 7 to the rear end of the hydraulic fracturing pipe 6, and install the composite connector 2, high pressure connector 4 and connecting ring 3 between the two pipes according to the above method;

[0150] Continue drilling, connect the rear end of the liquid CO2 phase change fracturing pipe 7 with the rear hole sealer 8, and install the composite connector 2, high-voltage connector 4, wire connector 5 and connecting ring 3 between the two pipes according to the above method. When installing the wire connector 5, align the rectangular wing 5004 on the plug 5003 with the position of the heating pipe connection port 7011, and complete the installation by plugging.

[0151] Continue drilling, connect the first set of drill rods 9 to the rear end of the rear hole sealer 8, and install the composite connector 2, high-voltage connector 4, wire connector 5 and connecting ring 3 between the rear end of the rear hole sealer 8 and the front end of the first set of drill rods 9 according to the above method;

[0152] Continue drilling, and install the second group of front hole sealers 15, the second group of hydraulic fracturing pipes 16, the second group of liquid CO2 phase change fracturing pipes 17, the second group of rear hole sealers 18 and the second group of drill pipes 10 in sequence at the rear end of the first group of drill pipes 9 according to the above method until the designed hole depth is reached;

[0153] S3, the coal seam is subjected to combined fracturing. First, the coal wall is damaged by the liquid CO2 phase change fracturing tube 7 at the first group of combined fracturing devices to form cracks, and then high-pressure hydraulic fracturing is performed by the hydraulic fracturing tube 6 to expand along the cracks until water flow occurs in the observation borehole 14;

[0154] Then, the second group of liquid CO2 phase change fracturing tubes 17 are used at the second group of combined fracturing devices to damage the coal wall and form cracks, and then high-pressure hydraulic fracturing is performed through the second group of hydraulic fracturing tubes 16, and the cracks are expanded along the cracks until water flows in the observation borehole 14;

[0155] Finally, the whole combined fracturing device is depressurized;

[0156] The specific steps of combined fracturing of coal seams are:

[0157] When the measure borehole 13 is constructed in place, the expansion capsule injection port and the expansion balloon injection port at the rear end of the second group of drill pipes 10 at the orifice of the measure borehole 13 are connected to manual high-pressure injection pumps respectively, and a total of 5 manual high-pressure injection pumps are needed, and the 4 expansion capsules in the combined fracturing device and the 2 expansion balloons of the first group and the expansion balloons of the second group of hydraulic fracturing pipes 16 are injected. When the internal pressures thereof reach 15 MPa respectively, the injection is stopped. At this time, the expansion capsules expand to realize the sealing function, and the plugs 6014 on the hydraulic fracturing pipe 6 and the second group of hydraulic fracturing pipes 16 will be pushed open. At the same time, the first expansion balloon 1012 in the front hole sealer 1 expands to block the fluid channel inside the entire combined fracturing device;

[0158] A detonator is connected to the first wire interface 10004 at the rear end of the second group of drill pipes 10 at the orifice of the measure borehole 13, and the spiral heating tube 7008 in the liquid CO2 phase change fracturing tube 7 is heated by the detonator to make the liquid CO2 in the liquid CO2 storage chamber 7012 undergo a phase change. When the internal pressure exceeds the breaking pressure of the constant pressure energy release sheet 7015, the constant pressure energy release sheet 7015 is broken, and the high-pressure CO2 gas impacts the coal body, causing damage to the coal wall on one side of the energy release port 7018 to form cracks. The energy release port 7018 faces the direction of the observation borehole 14.

[0159] Then, the high-pressure emulsion pump is connected to the combined fracturing device, and the second expansion balloon 6008 in the hydraulic fracturing pipe 6 is depressurized. At this time, the liquid outlet 6010 on the hydraulic fracturing pipe 6 will be connected to the fluid channel inside it, and high-pressure hydraulic fracturing is performed in the measure borehole 13 through the high-pressure emulsion pump. The high-pressure fluid will pass through the internal fluid channel of the combined fracturing device and the liquid outlet 6010 of the hydraulic fracturing pipe 6 into the borehole section blocked by the front sealer 1 and the rear sealer 8. Under continuous pressurization conditions, the high-pressure fluid will expand along the cracks formed by the phase change fracturing of liquid CO2 until water flows in the observation borehole 14, indicating that the hydraulic crack has expanded to the observation borehole 14 next to the measure borehole 13;

[0160] Stop hydraulic fracturing, and depressurize the fluid channel inside the combined fracturing device, then inject high-pressure water to 15MPa into the expansion balloon inside the second group of front sealers 15, and depressurize the two expansion balloons of the first group at the same time, then connect the detonator to the second wire interface 10005 at the rear end of the second group of drill pipes 10 at the orifice of the measure borehole 13, and use the detonator to make the liquid CO2 in the second group of liquid CO2 phase change fracturing tubes 17 undergo phase change, thereby damaging the coal wall and forming cracks;

[0161] The expansion balloon in the second group of hydraulic fracturing pipes 16 is depressurized. At this time, the liquid outlet on the second group of hydraulic fracturing pipes 16 will be connected to the fluid channel inside it, and the high-pressure emulsion pump is connected again. High-pressure hydraulic fracturing is performed in the measure borehole 13 through the high-pressure emulsion pump. The high-pressure fluid will pass through the internal fluid channel of the combined fracturing device and the liquid outlet of the second group of hydraulic fracturing pipes into the borehole section blocked by the second group of front sealers 15 and the second group of rear sealers 18. Under continuous pressurization conditions, the high-pressure fluid will expand along the cracks formed by the phase change fracturing of liquid CO2 until water flow appears again in the observation borehole 14, indicating that the hydraulic cracks at the second group of hydraulic fracturing positions in the measure borehole have expanded to the observation borehole 14 next to the measure borehole 13;

[0162] S4, the combined fracturing device is recovered. When the combined fracturing device is withdrawn from the measure borehole 13, the connecting ring 3, the high-voltage connector 4 and the wire connector 5 need to be removed first, and then the drilling rig is used to disassemble the pipes according to the normal procedure of disassembling the drill pipe, and the cycle is repeated until the combined fracturing device is completely taken out;

[0163] The specific steps for removing the connecting ring 3, the high voltage connector 4 and the wire connector 5 are as follows:

[0164] Before disassembling the adjacent pipes of the combined fracturing device, first use a flat-blade screwdriver to pry out the press covers 3006 on the two semicircular rings 3001 between the two pipes, then pry off the two semicircular rings 3001, and then remove the high-voltage connector 4 and the wire connector 5 connected between the two pipes in turn. The high-voltage connector 4 needs to be pressed and twisted before being removed, and the wire connector 5 can be directly unplugged by pulling out the plug 5003.

[0165] Embodiment 3

[0166] The method for using the liquid CO2 phase change and hydraulic combined fracturing device while drilling is described below by taking the coal mining face length of 120m, two combined fracturing positions are set in the measure borehole 13, and the observation borehole 14 is located 60m to the right of the measure borehole as an example:

[0167] like Fig.23 As shown, the length of the coal mining face is 120m, that is, the vertical distance between the return air tunnel 11 of the coal mining face and the air inlet tunnel 12 of the coal mining face is 120m, the length of the measure borehole 13 is set to 100m, and the joint fracturing positions in the measure borehole 13 are respectively located at the hole depths of 40m and 80m;

[0168] During the drilling process, the distance between the drill bit 19 and the front sealer 1 is 10m. The front sealer 1 is installed after the ordinary drill pipe 10 and the drill bit 19 drill 8m. Then, the hydraulic fracturing pipe 6, the liquid CO2 phase change fracturing pipe 7, the rear sealer 8 and the first group of drill pipes 9 are connected in sequence, and the drilling is continued for 40m. Then, the second group of front sealers 15, the second group of hydraulic fracturing pipes 16, the second group of liquid CO2 phase change fracturing pipes 17, the second group of rear sealers 18 and the second group of drill pipes 10 are installed in sequence, and the drilling is continued until the designed hole depth is reached. Then, the combined fracturing work is performed according to the method in Example 2;

[0169] During the combined fracturing process, when water flow appeared in the observation borehole 14, it indicated that the hydraulic fracture had extended to 60 m to the right of the measure borehole.

[0170] The above contents are only preferred embodiments of the present invention. For ordinary technicians in this field, many changes can be made in the specific implementation methods and application scopes based on the ideas of the present invention. As long as these changes do not deviate from the concept of the present invention, they all belong to the protection scope of the present invention.

Claims

1. A combined fracturing device for liquid CO2 phase change and hydraulic fracturing while drilling, characterized by: It comprises a sealing unit, a connecting unit and an additional investment unit, wherein the sealing unit comprises a front sealing device and a rear sealing device, the connecting unit comprises a composite connector, a connecting ring, a high-pressure connector, a wire connector and a drill pipe, the additional investment unit comprises a hydraulic fracturing pipe and a liquid CO2 phase-change fracturing pipe, the front sealing device and the rear sealing device are mounted on one end of different drill pipes, and the hydraulic fracturing pipe and the liquid CO2 phase-change fracturing pipe are mounted between the front sealing device and the rear sealing device, the front sealing device, the hydraulic fracturing pipe, the liquid CO2 phase-change fracturing pipe and the rear sealing device are connected by a connecting ring, the composite connector is mounted on the ends of the front sealing device, the hydraulic fracturing pipe, the liquid CO2 phase-change fracturing pipe, the rear sealing device and the drill pipe, and the composite connectors are connected by a high-pressure connector, and a wire connector is provided between the liquid CO2 phase-change fracturing pipe and the rear sealing device; The front hole sealer comprises a front hole sealer expansion capsule, a front hole sealer boss, a front hole sealer frame, a front hole sealer fixing platform, a first expansion balloon and a first expansion balloon connecting tube, the two ends of the front hole sealer frame are integrally formed with front hole sealer frustums, the front hole sealer expansion capsule is wrapped between the outside of the front hole sealer frame and the two front hole sealer frustums, the two front hole sealer bosses are respectively assembled on the outer ends of the two front hole sealer frustums, the interior of the front hole sealer frame is provided with a through front hole sealer fluid channel, the outer surface of one of the front hole sealer bosses is provided with a front hole sealer external thread, and the inner surface of the other front hole sealer boss is provided with a front seal The front hole sealer has an internal thread, the outer surface of the front hole sealer truncated cone is provided with a front hole sealer slot, a first liquid injection port for the expansion capsule and a first liquid injection port for the first expansion balloon, the front hole sealer fixing platform is fixedly installed on the inner end of the front hole sealer truncated cone, the inner end of the front hole sealer fixing platform is provided with an internal liquid injection port for the expansion capsule connected with the first liquid injection port of the expansion capsule and a first expansion balloon connecting tube connected with the first liquid injection port of the first expansion balloon, the first expansion balloon is assembled on the inner end of the first expansion balloon connecting tube, the outer surface of the front hole sealer frame is provided with a first balloon chamber connected with the fluid channel of the front hole sealer, and the first expansion balloon is located in the first balloon chamber; The rear hole sealer comprises a rear hole sealer frame, a rear hole sealer expansion capsule, a rear hole sealer boss, a rear hole sealer fixing platform and a rear hole sealer round platform, and the rear hole sealer frame, the rear hole sealer expansion capsule, the rear hole sealer boss, the rear hole sealer fixing platform and the rear hole sealer round platform have the same structure as the front hole sealer frame, the front hole sealer expansion capsule, the front hole sealer boss, the front hole sealer fixing platform and the front hole sealer round platform, and both ends of the rear hole sealer frame are equipped with rear hole sealer round platforms, and the two rear hole sealers are The hole sealer boss is assembled on the outer ends of the two rear hole sealer truncated cones, the two rear hole sealer fixing platforms are assembled on the inner ends of the two rear hole sealer truncated cones, the rear hole sealer expansion capsule is wrapped on the outside of the rear hole sealer frame, and the outer ends of the two rear hole sealer truncated cones are provided with a fourth liquid injection port for the expansion capsule, a first connecting port for the wire, a fourth liquid injection port for the first expansion balloon and a third liquid injection port for the second expansion balloon, and the rear hole sealer expansion capsule is connected in series with the front hole sealer expansion capsule.

2. A combined fracturing device for phase change and hydraulic fracturing of liquid CO2 while drilling according to claim 1, characterized in that: The composite connector includes a card table, an external thread connection end and a high-pressure joint connection end, and the external thread connection end and the high-pressure joint connection end are respectively assembled at both ends of the card table, a through hexagonal fluid channel is opened inside the card table, the external thread connection end is provided with a connector external thread, the high-pressure joint connection end is a high-pressure connection male head, and a screwing groove is opened on the outer surface of the card table; The connecting ring comprises a semicircular ring and a pressing cover. The two semicircular rings are assembled to form a ring structure. The surface of the semicircular ring is integrally formed with a convex tooth matching the slot of the front hole sealer. The outer surface of the end of the semicircular ring is provided with a concave platform matching the pressing cover. The inner surface of the concave platform is provided with a pin hole. The inner surface of the pressing cover is fixedly installed with a plug matching the pin hole. The outer peripheral surface of the plug is provided with barbs. The high-pressure connector includes a high-pressure hose and a high-pressure connecting female head, and the high-pressure connecting female head matches the high-pressure connecting male head. The two high-pressure connecting female heads are assembled at both ends of the high-pressure hose. The outer end of the high-pressure connecting female head is integrally formed with a card tooth matching the screwing card slot. After the composite connecting head is connected to the high-pressure connector, it is placed in the connecting ring.

3. A combined fracturing device for phase change and hydraulic fracturing of liquid CO2 while drilling according to claim 1, characterized in that: The hydraulic fracturing pipe comprises a fracturing pipe shell, a second expansion balloon, a fracturing pipe frame, a fracturing pipe cone and a fracturing pipe boss, and the fracturing pipe frame, the fracturing pipe boss and the fracturing pipe cone have the same structure as the front hole sealer frame, the front hole sealer boss and the front hole sealer cone. The fracturing pipe shell is assembled on the outside of the fracturing pipe frame, and both ends of the fracturing pipe frame are equipped with fracturing pipe cones. Two fracturing pipe bosses are assembled on the outer ends of two fracturing pipe cones. The outer ends of the two fracturing pipe cones are provided with a second injection port of the expansion capsule and a second injection port of the first expansion balloon. The outer end of one of the fracturing pipe cones is provided with a second expansion balloon. A first liquid injection port, a first liquid injection channel of the expansion capsule connected to the second liquid injection port of the expansion capsule and a first liquid injection channel of the first expansion balloon connected to the second liquid injection port of the first expansion balloon are arranged between the two fracturing tube cones, a second expansion balloon connecting tube connected to the first liquid injection port of the second expansion balloon is fixedly installed on the inner end of one of the fracturing tube cones, and the second expansion balloon is assembled on the inner end of the second expansion balloon connecting tube, a second balloon chamber is arranged between the fracturing tube shell and the fracturing tube frame, and the second expansion balloon is located in the second balloon chamber, a liquid outlet is opened on the surface of the fracturing tube shell, and a plug is assembled in the liquid outlet.

4. The combined fracturing device for phase change and hydraulic fracturing of liquid CO2 while drilling according to claim 1, characterized in that: The liquid CO2 phase change fracturing tube comprises a fracturing tube frame, a fracturing tube shell, a fracturing tube boss, a fracturing tube cone and a spiral heating tube, and the fracturing tube frame, the fracturing tube boss and the fracturing tube cone have the same structure as the front hole sealer frame, the front hole sealer boss and the front hole sealer cone. The fracturing tube shell is mounted on the outside of the fracturing tube frame, and both ends of the fracturing tube frame are equipped with fracturing tube cones. Two of the fracturing tube bosses are mounted on the outer ends of two of the fracturing tube cones. A liquid CO2 storage chamber is provided between the fracturing tube shell and the fracturing tube frame. The outer ends of the two fracturing tube cones are provided with a third liquid injection port of a first expansion balloon, a second liquid injection port of a second expansion balloon and a third liquid injection port of an expansion capsule. A liquid injection port connected to the third liquid injection port of the expansion capsule is provided between the two fracturing tube cones. The second liquid injection channel of the expansion capsule, the second liquid injection channel of the first expansion balloon connected with the third liquid injection port of the first expansion balloon, the first liquid injection channel of the second expansion balloon connected with the second liquid injection port of the second expansion balloon, a heating tube connection port is provided at the outer end of the fracturing tube truncated cone, a spiral heating tube is spirally wound in the liquid CO2 storage chamber, and the spiral heating tube is connected with the heating tube connection port, a first threaded hole and an energy release port are respectively provided at both ends of the surface of the fracturing tube shell, a liquid CO2 injection valve is installed in the first threaded hole, a second threaded hole is provided in the energy release port, a constant pressure energy release sheet is installed in the second threaded hole, a hexagonal energy release port is installed on the constant pressure energy release sheet, and the heating tube connection port is connected to the first connection port of the wire through a wire connector; The wire connector includes a hose, a base and a plug, the two bases are assembled at the two ends of the hose, the plug is fixedly installed on the outer end of the base, the outer circumference of the plug is symmetrically fixed with rectangular wings, the outer surface of the rectangular wings is fixedly installed with conductive protrusions, two wires are arranged inside the hose, and the two ends of the wires are respectively connected to the conductive protrusions on the two plugs.

5. The combined fracturing device for phase change and hydraulic fracturing of liquid CO2 while drilling according to claim 1, characterized in that: The drill rods include a first group of drill rods and common drill rods, the common drill rods are connected to one end of the front hole sealer, and the first group of drill rods are connected to one end of the rear hole sealer; A first group of drill rod fluid channels are provided inside the first group of drill rods, and a first group of drill rod external threads and a first group of drill rod internal threads are provided at both ends of the first group of drill rods respectively. A first group of drill rod slots, a second connecting port for a guide wire, a fifth liquid injection port for an expansion capsule, a fifth liquid injection port for a first expansion balloon, and a fourth liquid injection port for a second expansion balloon are provided at both ends of the first group of drill rods. The first group of drill rods are provided inside with a first expansion balloon third liquid injection channel connected to the fifth liquid injection port of the first expansion balloon, a second liquid injection channel of the second expansion balloon connected to the fourth liquid injection port of the second expansion balloon, a third liquid injection channel of the expansion capsule connected to the fifth liquid injection port of the expansion capsule, and a guide wire channel connected to the second connecting port of the guide wire.

6. A method for using a combined hydraulic fracturing device for phase change and hydraulic fracturing of liquid CO2 while drilling, using the combined hydraulic fracturing device for phase change and hydraulic fracturing of liquid CO2 while drilling as claimed in any one of claims 1 to 5, specifically The following steps are involved: S1, prepare construction equipment, including pre-installation of drilling construction equipment and combined fracturing device; S2, drilling construction, including ordinary drilling construction and measure drilling construction. Ordinary drilling construction is carried out using a drilling rig, a drill bit and an ordinary drill rod according to the normal drilling procedure. Ordinary drilling is used as an observation borehole to control the expansion distance of hydraulic fracturing cracks in the measure borehole; Measures Drilling construction is carried out according to the following steps: A, design of the location of joint fracturing inside the measure borehole; B, normal drilling, drilling of measure holes is carried out according to the above position design, the drill bit is installed on the ordinary drill rod, and the initial drilling is completed; C, the combined fracturing device is used with drilling. During the drilling process of the ordinary drill pipe, the front sealer, hydraulic fracturing pipe, liquid CO2 phase change fracturing pipe, rear sealer, and the first set of drill pipe are connected in sequence behind it to form the first set of combined fracturing device. Then, during the drilling process, the second set of front sealers, the second set of hydraulic fracturing pipes, the second set of liquid CO2 phase change fracturing pipes, the second set of rear sealers, and the second set of drill pipes are connected in sequence to form the second set of combined fracturing device until the drill bit reaches the designed hole depth; S3, conduct combined fracturing on the coal seam, firstly, at the first group of combined fracturing devices, the liquid CO2 phase change fracturing tube is used to damage the coal wall to form cracks, and then high-pressure hydraulic fracturing is performed through the hydraulic fracturing tube, and the cracks are expanded along the cracks until water flow occurs in the observation borehole; Then, the second group of liquid CO2 phase change fracturing tubes are used at the second group of combined fracturing devices to damage the coal wall and form cracks. Then, high-pressure hydraulic fracturing is carried out through the second group of hydraulic fracturing tubes, and the fracturing is expanded along the cracks until water flow appears in the observation borehole. Finally, the whole combined fracturing device is depressurized; S4, the combined fracturing device is recovered. When the entire combined fracturing device is withdrawn from the measure borehole, the connecting ring, high-voltage connector and wire connector need to be removed first, and then the drilling rig is used to disassemble each pipe according to the normal procedure for disassembling the drill pipe. This cycle is repeated until the entire combined fracturing device is completely taken out.

7. A method for using a combined liquid CO2 phase change and hydraulic fracturing device while drilling according to claim 6, characterized in that: In step S2, the specific steps of the combined fracturing device while drilling are: First, use the drilling rig to connect the front hole sealer to the rear of the ordinary drill pipe according to the normal procedure of connecting the drill pipe, and then continue drilling; When the front hole sealer enters the measure borehole, the drilling rig is used behind it to connect the external thread of the hydraulic fracturing pipe with the internal thread of the front hole sealer of the front hole sealer according to the normal procedure of connecting the drill pipe. After the connection is completed, the construction personnel use the external thread connection end of the composite connector to connect with the first injection port of the expansion capsule and the first injection port of the first expansion balloon at the rear end of the front hole sealer, and the high-pressure connector connection end of the composite connector is connected with the high-pressure connector. When connecting, a sealing ring is installed on the high-pressure connection male head of the composite connector, and the high-pressure connection female head of the high-pressure connector is screwed so that the clamping teeth on the high-pressure connection female head are clamped by the screwing clamping groove of the composite connector, and then the two semicircular rings of the connecting ring are installed to the rear end of the front hole sealer and the front end of the hydraulic fracturing pipe, so that the convex teeth are clamped in the clamping groove, and the two semicircular rings are connected as a whole by pressing the cover; Continue drilling, connect the liquid CO2 phase change fracturing pipe to the rear end of the hydraulic fracturing pipe, and install the composite connector, high pressure connector and connecting ring between the two pipes according to the above method; Continue drilling, connect the rear end of the liquid CO2 phase change fracturing pipe to the rear end of the hole sealer, and install the composite connector, high-voltage connector, wire connector and connecting ring between the two pipes according to the above method. When installing the wire connector, align the rectangular wing on the plug with the position of the heating pipe connection port, and complete the installation by plugging. Continue drilling, connect the first set of drill pipes to the rear end of the rear hole sealer, and install a composite connector, a high-voltage connector, a wire connector and a connecting ring between the rear end of the rear hole sealer and the front end of the first set of drill pipes according to the above method; Continue drilling, and install the second set of front sealers, the second set of hydraulic fracturing pipes, the second set of liquid CO2 phase change fracturing pipes, the second set of rear sealers and the second set of drill pipes in sequence at the rear end of the first set of drill pipes according to the above method until the designed hole depth is reached.

8. The method for using the combined phase change and hydraulic fracturing device for liquid CO2 while drilling according to claim 6, characterized in that: In step S3, the specific steps of performing combined fracturing on the coal seam are: When the measure drilling construction is in place, the expansion capsule injection port and the expansion balloon injection port at the rear end of the second group of drill pipes at the orifice of the measure drilling hole are connected to the manual high-pressure injection pump respectively, and the four expansion capsules in the combined fracturing device, the two expansion balloons in the first group, and the expansion balloons of the second group of hydraulic fracturing pipes are injected with liquid. When the internal pressures reach 15MPa, the injection is stopped. At this time, the expansion capsules expand to achieve the sealing function, and the plugs on the hydraulic fracturing pipe and the second group of hydraulic fracturing pipes will be pushed open. At the same time, the first expansion balloon in the front sealer expands to block the fluid channel inside the entire combined fracturing device; A detonator is connected to the first wire interface at the rear end of the second group of drill pipes at the orifice of the measure borehole, and the spiral heating tube in the liquid CO2 phase change fracturing tube is heated by the detonator to make the liquid CO2 in the liquid CO2 storage chamber undergo a phase change. When the internal pressure exceeds the breaking pressure of the constant pressure energy release plate, the constant pressure energy release plate is broken, and the high-pressure CO2 gas impacts the coal body, causing damage to the coal wall on one side of the energy release port to form cracks, and the energy release port faces the direction of the observation borehole; Then, the high-pressure emulsion pump is connected to the combined fracturing device, and the second expansion balloon in the hydraulic fracturing pipe is depressurized. At this time, the outlet on the hydraulic fracturing pipe will be connected to the fluid channel inside it, and high-pressure hydraulic fracturing is performed in the measure borehole through the high-pressure emulsion pump. The high-pressure fluid will enter the borehole section blocked by the front sealer and the rear sealer through the internal fluid channel of the combined fracturing device and the outlet of the hydraulic fracturing pipe. Under continuous pressurization conditions, the high-pressure fluid will expand along the cracks formed by the liquid CO2 phase change fracturing until water flows in the observation borehole, indicating that the hydraulic fracture has expanded to the observation borehole next to the measure borehole; Stop hydraulic fracturing, and depressurize the fluid channel inside the combined fracturing device. Then, inject high-pressure water to 15MPa into the expansion balloon inside the second group of front sealers. At the same time, depressurize the two expansion balloons in the first group. Then, connect the detonator to the second wire interface at the rear end of the second group of drill pipes at the orifice of the measure borehole. Use the detonator to make the liquid CO2 in the second group of liquid CO2 phase change fracturing tubes change phase, thereby damaging the coal wall and forming cracks. The expansion balloon in the second group of hydraulic fracturing pipes is depressurized. At this time, the liquid outlet on the second group of hydraulic fracturing pipes will be connected to the fluid channel inside it, and the high-pressure emulsion pump is connected again. High-pressure hydraulic fracturing is performed in the measure borehole through the high-pressure emulsion pump. The high-pressure fluid will pass through the internal fluid channel of the combined fracturing device and the liquid outlet of the second group of hydraulic fracturing pipes into the borehole section blocked by the second group of front sealers and the second group of rear sealers. Under continuous pressurization conditions, the high-pressure fluid will expand along the cracks formed by the liquid CO2 phase change fracturing until water flow appears again in the observation borehole, indicating that the hydraulic cracks at the second group of hydraulic fracturing positions in the measure borehole have expanded to the observation borehole next to the measure borehole.

9. The method for using the combined phase change and hydraulic fracturing device for liquid CO2 while drilling according to claim 6, characterized in that: In step S4, the specific steps of removing the connecting ring, the high voltage connector and the wire connector are: Before disassembling the adjacent pipes of the combined fracturing device, first use a flat-blade screwdriver to pry out the push covers on the two semicircular rings between the two pipes, then pry off the two semicircular rings, and then remove the high-voltage connector and wire connector connected between the two pipes in turn. The high-voltage connector needs to be pressed and twisted before being removed, and the wire connector can be directly unplugged.

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