Full-section hole cyclic loading and unloading fracturing device and coal mine hydraulic fracturing method

Abstract

The application discloses a full-section-hole cyclic loading and unloading fracturing device and a coal mine hydraulic fracturing method. The full-section-hole cyclic loading and unloading fracturing device comprises a fracturing pipe, a hole sealing bag, a water injection pipe, a sliding pipe and a limiting assembly. A plurality of first holes are arranged on the fracturing pipe. A fracturing space is defined between two adjacent hole sealing bags. The hole sealing bag is connected with the water injection pipe. The sliding pipe is movable in the inner cavity of the fracturing pipe. The end of the sliding pipe close to the bottom of the borehole is sealed. A second hole is arranged on the sliding pipe. The first holes and the second holes are divided into a plurality of fracturing hole groups. Each fracturing hole group comprises one first hole and one second hole. When the first hole and the second hole in one fracturing hole group are in communication, the first holes and the second holes in other fracturing hole groups are arranged in a staggered mode. The limiting assembly limits the position of the sliding pipe in the fracturing pipe and makes the first hole and the second hole in one fracturing hole group in communication. The application does not need to move the fracturing equipment, simplifies the fracturing process and improves the efficiency of the hydraulic fracturing.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of hydraulic fracturing, and particularly relates to a full-section-hole cyclic loading and unloading fracturing device and a coal mine hydraulic fracturing method. BACKGROUND

[0002] In related technologies, the fracturing device for coal mines is a bare hole section fracturing tool of a moving pipe column. After the fracturing drilling construction is completed, the fracturing device is placed in the drilling hole, and the packer is set. The space between the packer and the injection bag is the fracturing space. Since the fracturing space is small, the entire drilling hole cannot be fractured, and the drilling hole needs to be fractured in sections. After the cracks in a section of the fracturing space are initiated, the fracturing tool is moved to fracture the next section of the fracturing space. After the cracks in the entire drilling hole are initiated, hydraulic fracturing of the entire drilling hole is performed, and the cracks are expanded. SUMMARY

[0003] The present application is made based on the findings and understanding of the inventors on the following facts and problems:

[0004] The inventors have realized that the fracturing method in related technologies has problems such as complex process, long time consumption, high crack initiation pressure, and the inability of the coal mine fracturing pump set to match, which seriously affects the surrounding rock fracturing efficiency and the mining safety.

[0005] The present application aims to at least partially solve one of the technical problems in related technologies.

[0006] To this end, an embodiment of the present application provides a full-section-hole cyclic loading and unloading fracturing device, which has a simple fracturing process and improves the efficiency of hydraulic fracturing.

[0007] An embodiment of the present application also provides a coal mine hydraulic fracturing method.

[0008] The full-section-hole cyclic loading and unloading fracturing device of the present application comprises:

[0009] A fracturing pipe, a plurality of first holes are arranged on the fracturing pipe;

[0010] A plurality of packer bags are arranged on the outer side of the fracturing pipe along the extension direction of the fracturing pipe, and a fracturing space is defined between adjacent two packer bags. The first holes are arranged one by one corresponding to the fracturing space;

[0011] A water injection pipe, the water injection pipe is arranged in parallel with the fracturing pipe, and the packer bags are connected to the water injection pipe;

[0012] A sliding pipe is abutted with the inner wall of the fracturing pipe and is movable in the inner cavity of the fracturing pipe, one end of the sliding pipe is sealed near the bottom of the borehole, a plurality of second holes are arranged on the sliding pipe, the plurality of first holes and the plurality of second holes are divided into a plurality of fracturing hole groups, each fracturing hole group comprises one first hole and one second hole, and the first hole and the second hole in one of the fracturing hole groups are in communication while the first hole and the second hole in other fracturing hole groups are arranged in a staggered manner.

[0013] A limiting component is arranged between the fracturing pipe and the sliding pipe to limit the position of the sliding pipe in the fracturing pipe and to make the first hole and the second hole in one of the fracturing hole groups in communication.

[0014] The full-section hole circulating loading and unloading fracturing device of the embodiment of the present application does not need to move the fracturing equipment during the hydraulic fracturing process of the borehole, simplifies the fracturing process and improves the efficiency of the hydraulic fracturing.

[0015] In some embodiments, a plunger hole is arranged between the hole-sealing bag near the bottom of the borehole and the inner cavity of the fracturing pipe, and the limiting component comprises:

[0016] A plug is slidably arranged in the plunger hole, one end of the plug near the inner cavity has a spherical surface, and one end of the plug near the hole-sealing bag has an end plate;

[0017] A first elastic member is arranged between the end plate and the side wall of the fracturing pipe;

[0018] A second elastic member is arranged between one end of the sliding pipe near the bottom of the borehole and one end of the fracturing pipe near the bottom of the borehole;

[0019] A plurality of third holes are arranged on the side wall of the sliding pipe, the number of the third holes is the same as the number of the fracturing hole groups, and the plug is inserted into one of the third holes to limit the position, and the first hole and the second hole in one of the fracturing hole groups are in communication.

[0020] In some embodiments, the side wall of the sliding pipe has a fourth hole, the plug is inserted into the fourth hole to limit the position, and the sliding pipe is arranged in a staggered manner with the first hole to make the first hole directly communicate with the inner cavity of the fracturing pipe.

[0021] In some embodiments, the side wall of the fracturing pipe section corresponding to each fracturing space is provided with a first cavity, the side wall of the fracturing pipe section between two adjacent fracturing spaces is provided with a second cavity, the first cavity communicates with the corresponding first hole and the corresponding fracturing space, and the second cavity communicates two adjacent first cavities.

[0022] Further comprising a first adjusting assembly, which is arranged in the first cavity along the water injection direction of the fracturing pipe to control the connection or disconnection between the first cavity and the second cavity behind it.

[0023] In some embodiments, the first cavity has a partition plate, which divides the first cavity into a first chamber and a second chamber, the first chamber is in communication with the corresponding first hole, the first chamber and the second chamber are both in communication with the corresponding fracturing space, the second cavity is in communication with the second chamber of the former first cavity and the first chamber of the latter first cavity along the water injection direction of the fracturing pipe, and the first adjusting assembly is arranged in the second chamber.

[0024] In some embodiments, the second chamber is provided with a fifth hole between the corresponding fracturing space, the second chamber is provided with a sixth hole between the corresponding second cavity, the first adjusting assembly comprises a first slider and a third elastic member, the first slider is arranged in the corresponding second chamber, the third elastic member is arranged between the first slider and the inner wall of the second chamber, the circumferential surface of the first slider is sealed with the inner wall of the second chamber, the fifth hole and the sixth hole are located on the two sides of the first slider in the disconnected state of the second chamber and the corresponding second cavity, and the fifth hole and the sixth hole are located on the same side of the first slider in the connected state of the second chamber and the corresponding second cavity.

[0025] In some embodiments, further comprising a second adjusting assembly, which is arranged in the first chamber, the first chamber is provided with a seventh hole between the corresponding fracturing space, the second adjusting assembly comprises a second slider and a fourth elastic member, the second slider is arranged in the corresponding first chamber, the fourth elastic member is arranged between the second slider and the inner wall of the first chamber, the circumferential surface of the second slider is sealed with the inner wall of the first chamber, the first hole and the seventh hole are located on the two sides of the second slider in the disconnected state of the first chamber and the corresponding fracturing space, and the first hole and the seventh hole are located on the same side of the second slider in the connected state of the first chamber and the corresponding fracturing space.

[0026] The coal mine hydraulic fracturing method of the embodiment of the present application comprises:

[0027] S101, drilling a hole;

[0028] S102, arranging the full-section hole cyclic loading and unloading fracturing device in any of the above embodiments in the hole, and injecting water into the hole sealing bag to make the hole sealing bag set and seal in the hole;

[0029] S103, water is injected into the fracturing pipe, the sliding pipe moves relative to the fracturing pipe, so that the plug in the limiting assembly is inserted into the third hole on the sliding pipe, and the fracturing hole group corresponding to the first section of the fracturing space is conducted, water is injected into the fracturing space and fracturing is carried out;

[0030] S104, the water injection pressure of the fracturing pipe is increased, the plug in the limiting assembly is retracted by the sliding pipe, so that the sliding pipe continues to move relative to the fracturing pipe, and the plug in the limiting assembly is inserted into the next third hole on the sliding pipe, and the fracturing hole group corresponding to the second section of the fracturing space is conducted, water is injected into the fracturing space and fracturing is carried out;

[0031] S105, repeat the previous step to carry out fracturing work on the fracturing space section by section.

[0032] In some embodiments, the fracturing pipe has a first cavity, a second cavity, a first adjusting assembly and a second adjusting assembly; the step of injecting water into the fracturing space and carrying out fracturing includes:

[0033] The water in the fracturing pipe enters the first chamber of the first cavity and pushes the second sliding block in the second adjusting assembly to move, so that the first chamber and the corresponding fracturing space are communicated, and water flows into the fracturing space;

[0034] When the crack of the fracturing space is initiated, and the water pressure in the fracturing space and the second chamber of the first cavity increases to a first threshold value, the first sliding block in the first adjusting assembly is pushed to move, so that the second chamber and the first chamber of the next section of the fracturing space are communicated through the second cavity therebetween.

[0035] In some embodiments, the method further comprises the following steps:

[0036] S106, after completing the fracturing work on each of the fracturing spaces in the borehole section by section, releasing the water in the hole sealing bag and the fracturing pipe, and unloading the entire borehole;

[0037] S107, the sliding pipe, the first adjusting assembly and the second adjusting assembly in the full-section hole cyclic loading and unloading fracturing device are reset;

[0038] S108, repeat steps S103 to S107 to carry out multiple cyclic loading and unloading fracturing operations;

[0039] S109, water is injected into the hole sealing bag to make the hole sealing bag set in the borehole, water is injected into the fracturing pipe, the sliding pipe moves relative to the fracturing pipe, and the plug in the limiting assembly is inserted into the fourth hole on the sliding pipe, water injection into the first section of the fracturing space is continued, and multiple sections of the fracturing space are communicated through the second cavity to realize common fracturing of the borehole. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the structure of the full-section hole circulation loading and unloading fracturing device according to an embodiment of the present invention.

[0041] Figure 2 This is a schematic diagram of the slide tube according to an embodiment of the present invention.

[0042] Figure 3 This is a partially enlarged structural schematic diagram of the full-section hole circulation loading and unloading fracturing device according to an embodiment of the present invention.

[0043] Figure 4 This is a schematic diagram of the structure of the limiting component according to an embodiment of the present invention.

[0044] Figure label:

[0045] 1. Fracturing tube; 11. First hole; 12. First cavity; 121. First chamber; 122. Second chamber; 123. Partition; 13. Second cavity;

[0046] 2. Sealed bag;

[0047] 3. Water injection pipe;

[0048] 4. Sliding tube; 41. Second hole; 42. Third hole; 43. Fourth hole; 44. Second elastic element;

[0049] 5. Limiting component; 51. Insert post; 52. First elastic element; 53. End plate;

[0050] 61. Fifth hole; 62. Sixth hole; 63. Seventh hole;

[0051] 7. First adjusting component; 71. First slider; 72. Third elastic element;

[0052] 8. Second adjustment component; 81. Second slider; 82. Fourth elastic element. Detailed Implementation

[0053] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0054] like Figure 1 and Figure 2As shown, the full-hole cyclic loading and unloading fracturing device of the embodiment of the present application comprises a fracturing pipe 1, a hole sealing bag 2 and a water injection pipe 3, the fracturing pipe 1 is provided with a plurality of first holes 11; a plurality of hole sealing bags 2 are arranged on the outer side of the fracturing pipe 1 along the extension direction of the fracturing pipe 1, the hole sealing bags 2 are arranged at intervals, and the adjacent two hole sealing bags 2 define a fracturing space, and the first holes 11 are arranged in one-to-one correspondence with the fracturing spaces; the water injection pipe 3 is arranged in parallel with the fracturing pipe 1, and the hole sealing bag 2 is communicated with the water injection pipe 3.

[0055] The hole sealing bag 2 is wrapped around the circumference of the fracturing pipe 1, when water is injected into the hole sealing bag 2 through the water injection pipe 3, the hole sealing bag 2 expands, so that the outer wall surface of the hole sealing bag 2 abuts and seals with the inner wall of the borehole, and the adjacent two hole sealing bags 2 form a fracturing space, and when water is injected into the fracturing space through the fracturing pipe 1, the fracturing operation can be performed on the fracturing space.

[0056] The full-hole cyclic loading and unloading fracturing device of the embodiment of the present application further comprises a sliding pipe 4 and a limiting component 5, the outer wall of the sliding pipe 4 is abutted with the inner wall of the fracturing pipe 1, and the sliding pipe 4 is movable in the inner cavity of the fracturing pipe 1, one end of the sliding pipe 4 close to the bottom of the borehole is sealed, the sliding pipe 4 is provided with a plurality of second holes 41, and the plurality of first holes 11 and the plurality of second holes 41 are divided into a plurality of fracturing hole groups, each fracturing hole group comprises one first hole 11 and one second hole 41, and the first hole 11 and the second hole 41 in one of the fracturing hole groups are in communication, and the first holes 11 and the second holes 41 in the other fracturing hole groups are arranged in a staggered manner.

[0057] The limiting component 5 is arranged between the fracturing pipe 1 and the sliding pipe 4, so as to limit the position of the sliding pipe 4 in the fracturing pipe 1 and make the first hole 11 and the second hole 41 in one of the fracturing hole groups in communication.

[0058] In work, in order to perform the fracturing operation on the plurality of fracturing spaces step by step, the sliding pipe 4 is arranged in the fracturing pipe 1, the sliding pipe 4 can slide in the fracturing pipe 1, the outer wall of the sliding pipe 4 is abutted and sealed with the inner wall of the fracturing pipe 1, when one of the second holes 41 on the sliding pipe 4 is aligned with one of the first holes 11 on the fracturing pipe 1, the water in the fracturing pipe 1 can flow into the fracturing space through the communicated fracturing hole group. The relative position between the fracturing pipe 1 and the sliding pipe 4 is controlled by the limiting component 5, so as to ensure that the sliding pipe 4 and the fracturing pipe 1 are aligned accurately and the first hole 11 and the second hole 41 in one of the fracturing hole groups are in communication, and the step-by-step fracturing work is facilitated.

[0059] The full-hole cyclic loading and unloading fracturing device of the embodiment of the present application does not need to move the fracturing equipment in the hydraulic fracturing process of the borehole, simplifies the fracturing process, and improves the efficiency of the hydraulic fracturing.

[0060] As shown in the figure, Figure 1 and Figure 4As shown, in some embodiments, a plunger hole is provided between the sealing bag 2 near the bottom of the borehole and the inner cavity of the fracturing pipe 1, the limiting assembly 5 includes a plunger 51, a first elastic member 52 and a second elastic member 44, the plunger 51 is slidingly arranged in the plunger hole, the end of the plunger 51 near the inner cavity has a spherical surface, and the end of the plunger 51 near the sealing bag 2 has an end plate 53; the first elastic member 52 is arranged between the end plate 53 and the side wall of the fracturing pipe 1, and the second elastic member 44 is arranged between the end of the sliding pipe 4 near the bottom of the borehole and the end of the fracturing pipe 1 near the bottom of the borehole; a plurality of third holes 42 are arranged on the side wall of the sliding pipe 4, the number of the third holes 42 is the same as the number of the fracturing hole groups, and the plunger 51 is inserted into one of the third holes 42 to limit, and the first hole 11 and the second hole 41 in one of the fracturing hole groups are in communication.

[0061] The plunger 51 is arranged in the plunger hole and can move in the axial direction of the plunger hole, the first elastic member 52 and the second elastic member 44 can both be springs, the first elastic member 52 is arranged between the end plate 53 of the plunger 51 and the side wall of the fracturing pipe 1, so as to provide a restoring force for the plunger 51, so that the plunger 51 is in a reset state in a non-working state and does not interfere with other components.

[0062] The sealing bag 2 needs to be first set, so a certain water pressure is always maintained in the sealing bag 2, and the water pressure in the sealing bag 2 acts on the plunger 51 to move the plunger 51 towards the center of the fracturing pipe 1. When water is injected into the fracturing pipe 1, the sliding pipe 4 moves under the action of the water in the fracturing pipe 1, and when the sliding pipe 4 pushes against the spherical surface of the plunger 51, the water pressure in the fracturing pipe 1 acts on the sliding pipe 4 to push the sliding pipe 4 to retract the plunger 51, and when the plunger 51 is aligned with the third hole 42 on the sliding pipe 4 closest to the bottom of the borehole, the plunger 51 extends into the third hole 42, and at the same time, the first hole 11 and the second hole 41 at the port closest to the borehole are aligned and in communication, and at this time, the water pressure in the fracturing pipe 1 can be adjusted to prevent the sliding pipe 4 from continuing to move, and the water in the fracturing pipe 1 enters the first fracturing space for fracturing operation.

[0063] When the fracturing operation of the next fracturing space is needed, the water pressure in the fracturing pipe 1 is increased, and the force of the sliding pipe 4 acting on the spherical surface of the plunger 51 can again retract the plunger 51 until the plunger 51 is inserted into the next third hole 42 on the sliding pipe 4, at which time the first hole 11 and the second hole 41 in the fracturing hole group aligned with the second fracturing space are in communication, and the water in the fracturing pipe 1 enters the first fracturing space for fracturing operation.

[0064] The position of the sliding pipe 4 is adjusted and limited in this way, and the fracturing operation of multiple fracturing spaces is performed step by step.

[0065] The second elastic element 44 provides a reset force for the slide tube 4. After the fracturing tube 1 and the sealing bag 2 are depressurized, the slide tube 4 will be reset to its initial position under the action of the second elastic element 44.

[0066] like Figures 1-4 As shown, in some embodiments, a first cavity 12 is provided on the sidewall of the fracturing tube 1 section corresponding to each fracturing space, and a second cavity 13 is provided on the sidewall of the fracturing tube 1 section between two adjacent fracturing spaces. The first cavity 12 is connected to the corresponding first hole 11 and the corresponding fracturing space, and the second cavity 13 is connected to two adjacent first cavities 12. The full-section hole circulation loading and unloading fracturing device also includes a first adjustment component 7. Along the water injection direction of the fracturing tube 1, the first adjustment component 7 is provided in the first cavity 12 to control the first cavity 12 to be connected or disconnected from the second cavity 13 located behind it.

[0067] In other words, the water in the fracturing tube 1 first enters the first chamber 12 through the first hole 11, and then flows into the fracturing space from the first chamber 12. When the water pressure in the fracturing space increases to the preset pressure, the first regulating component 7 can be activated and the first chamber 12 and the second chamber 13 located behind it can be connected. Some of the water in the first chamber 12 will flow into the first chamber 12 corresponding to the next fracturing space through the second chamber 13. At this time, the water pressure in the previous fracturing space decreases, and the fracturing operation of the previous fracturing space ends. By moving the slide tube 4, the next fracturing space is fracturing, and the previous fracturing space is depressurized.

[0068] The embodiments of the present invention, through the setting of the first cavity 12 and the second cavity 13, can make two adjacent fracturing spaces relatively independent during normal operation, and after the fracturing of the previous fracturing space is completed, the two adjacent fracturing spaces can be connected to depressurize the previous fracturing space.

[0069] In some embodiments, the first cavity 12 has a partition 123 that divides the first cavity 12 into a first chamber 121 and a second chamber 122. The first chamber 121 is connected to the corresponding first hole 11. Both the first chamber 121 and the second chamber 122 are connected to the corresponding fracturing space. Along the water injection direction of the fracturing pipe 1 (i.e., from right to left in the figure), the second cavity 13 connects the second chamber 122 of the previous first cavity 12 and the first chamber 121 of the next first cavity 12. The first adjustment component 7 is disposed in the second chamber 122.

[0070] That is, the first cavity 12 is divided into a first chamber 121 and a second chamber 122, the first chamber 121 and the second chamber 122 are relatively independent, when water is injected into the fracturing space, the water in the fracturing pipe 1 enters the first chamber 121 through the first hole 11 first, the water in the first chamber 121 enters the fracturing space to perform the fracturing operation, the fracturing space is in communication with the first chamber 121 and the second chamber 122, therefore, the water pressure of the fracturing space and the second chamber 122 is the same, when the water pressure in the fracturing space and the second chamber 122 reaches a preset pressure, the first adjusting assembly 7 will act and connect the second chamber 122 and the second cavity 13 adjacent to the second chamber 122, so that part of the water enters the first chamber 121 of the first cavity 12 corresponding to the next fracturing space.

[0071] Further, the fifth hole 61 is arranged between the second chamber 122 and the corresponding fracturing space, the sixth hole 62 is arranged between the second chamber 122 and the corresponding second cavity 13, the first adjusting assembly 7 comprises a first slider 71 and a third elastic member 72, the first slider 71 is arranged in the corresponding second chamber 122, the third elastic member 72 is arranged between the first slider 71 and the inner wall of the second chamber 122, the circumferential surface of the first slider 71 is sealed with the inner wall of the second chamber 122, in the disconnected state of the second chamber 122 and the corresponding second cavity 13, the fifth hole 61 and the sixth hole 62 are located on the two sides of the first slider 71, in the connected state of the second chamber 122 and the corresponding second cavity 13, the fifth hole 61 and the sixth hole 62 are located on the same side of the first slider 71.

[0072] Under normal conditions, under the action of the third elastic member 72, the fifth hole 61 and the sixth hole 62 are located on the two sides of the first slider 71, the fifth hole 61 and the sixth hole 62 are not connected, and the water in the fracturing space cannot enter the first chamber 121 corresponding to the next fracturing space through the second cavity 13.

[0073] When the water pressure in the fracturing space reaches the preset pressure, the water pressure of the fracturing space and the second chamber 122 is the same, the first slider 71 can be pushed to overcome the force of the third elastic member 72, so that the first slider 71 moves until the fifth hole 61 and the sixth hole 62 are located on the same side of the first slider 71, at this time, the water in the previous fracturing space can enter the first chamber 121 corresponding to the next fracturing space through the second chamber 13 between the two fracturing spaces and the second chamber 122 corresponding to the previous fracturing space.

[0074] Further, the full-section hole cyclic loading and unloading fracturing device further comprises a second adjusting assembly 8 arranged in the first chamber 121, the first chamber 121 is provided with a seventh hole 63 corresponding to the fracturing space, the second adjusting assembly 8 comprises a second sliding block 81 and a fourth elastic member 82, the second sliding block 81 is arranged in the corresponding first chamber 121, the fourth elastic member 82 is arranged between the second sliding block 81 and the inner wall of the first chamber 121, the circumferential surface of the second sliding block 81 is sealed with the inner wall of the first chamber 121, the first hole 11 and the seventh hole 63 are located on the two sides of the second sliding block 81 in the disconnected state of the first chamber 121 and the corresponding fracturing space, and the first hole 11 and the seventh hole 63 are located on the same side of the second sliding block 81 in the connected state of the first chamber 121 and the corresponding fracturing space.

[0075] The working principle of the first adjusting assembly 7 is the same as that in the normal state, under the action of the fourth elastic member 82, the first hole 11 and the seventh hole 63 are located on the two sides of the second sliding block 81, the first hole 11 and the seventh hole 63 are not connected, and the water in the fracturing pipe 1 cannot enter the fracturing space through the first chamber 121.

[0076] When the water pressure in the fracturing pipe 1 reaches the preset pressure, the second sliding block 81 can be pushed to overcome the force of the fourth elastic member 82, so that the second sliding block 81 moves until the first hole 11 and the seventh hole 63 are located on the same side of the second sliding block 81, at this time, the water in the fracturing pipe 1 can enter the corresponding fracturing space through the first chamber 121.

[0077] The first adjusting assembly 7 and the second adjusting assembly 8 can drive the action according to the size of the water pressure, and then realize the connection of the adjacent chambers under the preset pressure, thereby reducing the control difficulty and improving the practicability in the fracturing process.

[0078] The third elastic member 72 and the fourth elastic member 82 in the above embodiment are springs.

[0079] In some embodiments, the side wall of the sliding pipe 4 is provided with a fourth hole 43, when the plug column 51 is inserted and limited in the fourth hole 43, the sliding pipe 4 is arranged in a staggered manner with the first hole 11 to make the first hole 11 directly communicate with the inner cavity of the fracturing pipe 1.

[0080] It should be understood that when the plug column 51 is inserted and limited in the fourth hole 43, at least one first hole 11 on the fracturing pipe 1 is arranged in a complete staggered manner with the sliding pipe 4, the water in the fracturing pipe 1 can be directly injected into the corresponding fracturing space through the first hole 11, and the plurality of fracturing spaces are connected through the plurality of second cavities 13, thereby facilitating the simultaneous fracturing operation of the plurality of fracturing spaces of the entire drilling hole.

[0081] The coal mine hydraulic fracturing method of the embodiment of the present application comprises:

[0082] S101, drilling a hole; specifically, drilling a fracturing hole along a design parameter in a roadway or on the ground using a drilling machine.

[0083] S102, arranging the full-hole cyclic loading and unloading fracturing device in any of the embodiments above in the hole, and injecting water into the hole-sealing bag to make the hole-sealing bag set in the hole.

[0084] After the full-hole cyclic loading and unloading fracturing device is arranged in the hole, the water injection pipe is connected to the pump group, the water flow enters the hole-sealing bag, and the bag expands and sets. At this time, the plug is present in the hole-sealing bag near the bottom of the hole, and under the action of the water pressure in the hole-sealing bag, the plug is inserted into the fracturing pipe.

[0085] S103, injecting water into the fracturing pipe, moving the sliding pipe relative to the fracturing pipe, so that the plug in the limiting assembly is inserted into the third hole on the sliding pipe, and the fracturing hole group corresponding to the first fracturing space is conducted, water is injected into the fracturing space and fracturing is carried out.

[0086] Sliding pipe movement: connect the fracturing pipe to the pump group, the water flow enters the fracturing pipe, the pressure in the pipe rises, the sliding pipe is pushed by the water and moves relative to the fracturing pipe towards the bottom of the hole, the sliding pipe contacts the plug, and because the end of the plug is a smooth hemisphere, when the pushing force acting on the sliding pipe is large enough, the plug can be pushed back.

[0087] As the sliding pipe continues to move, the third hole on the sliding pipe closest to the bottom of the hole corresponds to the plug, and the second hole closest to the hole opening corresponds to the first hole on the fracturing pipe closest to the hole opening (a1 and b1 shown in the figure), part of the water in the fracturing pipe will flow to the first fracturing space, the pressure in the fracturing pipe decreases, and the plug is inserted into the corresponding third hole (T1 shown in the figure), and the sliding pipe stops moving.

[0088] When the fracturing pipe has a first cavity, a second cavity, a first adjusting assembly and a second adjusting assembly, the water in the fracturing pipe enters the first chamber of the first cavity, and pushes the second sliding block in the second adjusting assembly to move, so that the first chamber and the corresponding fracturing space are communicated, and the water flows into the fracturing space; as the cracks in the fracturing space crack and the water pressure in the fracturing space and the second chamber of the first cavity increases to the first threshold value, the first sliding block in the first adjusting assembly is pushed to move, so that the second chamber and the first chamber of the next fracturing space are communicated through the second cavity between them.

[0089] That is, the water in the fracturing pipe first enters the first chamber, the water flow converges in the first chamber corresponding to the first section of the fracturing space, the pressure rises, pushing the second slider to move, until the first chamber and the first section of the fracturing space are connected (at this time, the first hole corresponding to the first section of the fracturing space and the seventh hole are located on the same side of the second slider), the water flow enters the first section of the fracturing space, and the water in the first section of the fracturing space also flows into the second chamber. While the fracturing space is fractured and the water pressure in the second chamber of the first cavity increases to the first threshold value, the first slider in the first adjusting assembly is pushed to move to connect the second chamber and the first chamber of the next section of the fracturing space through the second cavity therebetween, and part of the water flows into the first chamber corresponding to the next section of the fracturing space.

[0090] S104, increase the water injection pressure of the fracturing pipe, retract the insert column in the sliding pipe limiting assembly to make the sliding pipe continue to move relative to the fracturing pipe, and make the insert column in the limiting assembly be inserted with the next third hole on the sliding pipe, while the fracturing hole group corresponding to the second section of the fracturing space is connected, water is injected into the fracturing space and fracturing is performed.

[0091] After the water injection pressure of the fracturing pipe is increased, the force acting on the sliding pipe can push the insert column to retract, so that the sliding pipe continues to move in the direction close to the bottom of the borehole, and then the insert column is inserted with another third hole (T2) on the sliding pipe. At this time, the second hole and the first hole (a1 and b1) corresponding to the first section of the fracturing space are staggered, and the second hole and the first hole (a2 and b2) corresponding to the second section of the fracturing space are connected. The water flow no longer enters the first section of the fracturing space, the internal pressure of the first section of the fracturing space continues to decrease, the pressure of the second section of the fracturing space rises, the first adjusting assembly and the second adjusting assembly corresponding to the first section of the fracturing space reset, the water flow no longer flows between the first and second fracturing spaces, and the first section of the fracturing space is depressurized.

[0092] S105, repeat the previous step to perform fracturing work on the fracturing space section by section. By repeating step 104, the third section of the fracturing space, the fourth section of the fracturing space, …, and the n section of the fracturing space can be fractured section by section.

[0093] Further, the coal mine hydraulic fracturing method further comprises the following steps:

[0094] S106, after completing the fracturing work of each fracturing space in the borehole section by section, release the water in the hole sealing bag and the fracturing pipe to depressurize the entire section of the borehole.

[0095] S107, reset the sliding pipe, the first adjusting assembly, and the second adjusting assembly in the full-section hole cyclic loading and unloading fracturing device.

[0096] When n segments of the fracturing space are subjected to one cycle of loading and unloading, the surrounding rock of the borehole is damaged. The water injection pipe is opened, the water pressure in the hole sealing bag is released, the hole sealing bag is retracted, the fracturing space is connected, the water flow is lost, and the whole segment is unloaded. At the same time, the column is retracted, the water flow in the fracturing pipe is released, the sliding pipe returns to the initial state, and each first adjusting assembly and each second adjusting assembly are also reset.

[0097] S108, repeating steps S103 to S107, performing multiple cycles of loading and unloading fracturing operation. The in-hole cycle loading and unloading of the whole segment fracturing hole is performed, the surrounding rock mass of the borehole is damaged, and the crack initiation pressure is reduced.

[0098] S109, water is injected into the hole sealing bag to make the hole sealing bag set in the borehole, water is injected into the fracturing pipe, the sliding pipe moves relative to the fracturing pipe, and the column in the limiting assembly is inserted into the fourth hole on the sliding pipe. Water is continuously injected into the first segment of the fracturing space, and multiple segments of the fracturing space are connected through the second cavity to achieve common fracturing of the borehole.

[0099] After the whole segment fracturing hole cycle loading and unloading fracturing operation, the hole sealing bag is set, water is injected into the fracturing pipe, the water pressure is continuously increased, the sliding pipe is continuously moved, and one of the first holes (at least including the first hole b1) is directly connected with the fracturing pipe, the column is inserted into the fourth hole on the sliding pipe, the sliding pipe no longer moves, the water flow enters the first segment of the fracturing space, the pressure is continuously increased, the first adjusting assembly and the second adjusting assembly corresponding to the first segment of the fracturing space are actuated, and the water flows into the subsequent fracturing space, until the nth segment of the fracturing space, the pressure of the n segments of the fracturing space is the same, and the borehole is commonly fractured.

[0100] In the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0101] In addition, the terms "first" and "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined as "first" and "second" can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise specifically limited.

[0102] In the present application, unless specifically defined otherwise, the terms "mounting", "connected", "connecting", "fixed", "fixedly connected", "connection", "fixedly connected", "connected", "fixed", and the like should be construed broadly, for example, can be fixed connection, can be detachable connection, or integral; can be mechanical connection, can be electrical connection or communication with each other; can be directly connected, or indirectly connected through an intermediate medium, can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise specifically defined. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0103] In the present application, unless specifically defined otherwise, the first feature is "on" or "under" the second feature. The first and second features can be in direct contact, or the first and second features can be in indirect contact through an intermediate medium. Moreover, the first feature "above", "over" and "on" the second feature can be that the first feature is directly above or obliquely above the second feature, or only indicates that the first feature is higher than the second feature in horizontal height. The first feature "below", "under" and "under" the second feature can be that the first feature is directly below or obliquely below the second feature, or only indicates that the first feature is lower than the second feature in horizontal height.

[0104] In the present application, the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine different embodiments or examples described in the specification and the features of different embodiments or examples without contradiction.

[0105] Although the embodiments of the present application have been shown and described above, it should be understood that the above embodiments are exemplary and should not be construed as limiting the present application. Those skilled in the art can make changes, modifications, replacements and variations to the above embodiments within the scope of the present application.

Claims

1. A full-frac, hole-cycling, load-and- unload fracturing apparatus, characterized by, The utility model relates to a fracturing device, which comprises a fracturing pipe, a plurality of first holes arranged on the fracturing pipe, a plurality of sealing bags arranged on the outer side of the fracturing pipe along the extension direction of the fracturing pipe, a fracturing space defined between two adjacent sealing bags, the first holes and the fracturing spaces one-to-one corresponding arrangement, a water injection pipe arranged in parallel with the fracturing pipe, the sealing bags and the water injection pipe being in communication, a sliding pipe, the outer wall of the sliding pipe being in abutment with the inner wall of the fracturing pipe, the sliding pipe being movable in the inner cavity of the fracturing pipe, the end of the sliding pipe close to the bottom of the borehole being sealed, a plurality of second holes being arranged on the sliding pipe, the plurality of first holes and the plurality of second holes being divided into a plurality of fracturing hole groups, each fracturing hole group comprising one first hole and one second hole, the first holes and the second holes in one fracturing hole group being in communication, and the first holes and the second holes in other fracturing hole groups being arranged in a staggered manner, a limiting component arranged between the fracturing pipe and the sliding pipe to limit the position of the sliding pipe in the fracturing pipe and make the first holes and the second holes in one fracturing hole group in communication, a plunger hole being arranged between the sealing bag close to the bottom of the borehole and the inner cavity of the fracturing pipe, the limiting component comprising a plug, the plug being slidably arranged in the plunger hole, the end of the plug close to the inner cavity having a spherical surface, the end of the plug close to the sealing bag having an end plate, a first elastic member arranged between the end plate and the side wall of the fracturing pipe, a second elastic member arranged between the end of the sliding pipe close to the bottom of the borehole and the end of the fracturing pipe close to the bottom of the borehole, a plurality of third holes being arranged on the side wall of the sliding pipe, the number of the third holes being the same as the number of the fracturing hole groups, the plug being inserted into one third hole to limit the position, and the first holes and the second holes in one fracturing hole group being in communication, the side wall of the sliding pipe having a fourth hole, the plug being inserted into the fourth hole to limit the position, the sliding pipe being arranged in a staggered manner with the first holes to make the first holes directly communicate with the inner cavity of the fracturing pipe, the side wall of the fracturing pipe section corresponding to each fracturing space having a first cavity, the side wall of the fracturing pipe section between two adjacent fracturing spaces having a second cavity, the first cavity being in communication with the corresponding first hole and the corresponding fracturing space, and the second cavity being in communication with two adjacent first cavities, a first adjusting component being arranged in the first cavity to control the first cavity and the second cavity located behind the first cavity to be in communication or disconnected along the water injection direction of the fracturing pipe. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2. The full bore cyclic pressurization and depressurization fracturing device of claim 1, wherein, ​ 3. The full- segment pore cyclic pressurization-depressurization fracturing device according to any one of claims 1-2, characterized in that, ​ ​ 4. The full bore cyclic pressurization and depressurization fracturing device of claim 3, wherein, The first cavity has a partition plate, which divides the first cavity into a first chamber and a second chamber, the first chamber communicates with the corresponding first hole, the first chamber and the second chamber both communicate with the corresponding fracturing space, the second cavity communicates the second chamber of the previous first cavity and the first chamber of the next first cavity along the water injection direction of the fracturing pipe, and the first adjusting assembly is arranged in the second chamber.

5. The full bore cyclic pressurization and depressurization fracturing device of claim 4, wherein, The second chamber is provided with a fifth hole between the corresponding fracturing space, and a sixth hole between the corresponding second cavity, the first adjusting assembly comprises a first slider and a third elastic member, the first slider is arranged in the corresponding second chamber, the third elastic member is arranged between the first slider and the inner wall of the second chamber, the circumferential surface of the first slider is sealed with the inner wall of the second chamber, the fifth hole and the sixth hole are located on the two sides of the first slider in the disconnected state of the second chamber and the corresponding second cavity, and the fifth hole and the sixth hole are located on the same side of the first slider in the conductive state of the second chamber and the corresponding second cavity.

6. The full- segmental- pore cyclic pressurization and depressurization fracturing device according to claim 5, characterized in that, The second adjusting assembly is further arranged in the first chamber, the first chamber is provided with a seventh hole between the corresponding fracturing space, the second adjusting assembly comprises a second slider and a fourth elastic member, the second slider is arranged in the corresponding first chamber, the fourth elastic member is arranged between the second slider and the inner wall of the first chamber, the circumferential surface of the second slider is sealed with the inner wall of the first chamber, the first hole and the seventh hole are located on the two sides of the second slider in the disconnected state of the first chamber and the corresponding fracturing space, and the first hole and the seventh hole are located on the same side of the second slider in the conductive state of the first chamber and the corresponding fracturing space.

7. A coal mine hydraulic fracturing method, characterized by, It comprises: S101, drilling a hole; S102, arranging the full-section hole cyclic loading and unloading fracturing device according to any one of claims 5 to 6 in the hole, and injecting water into the hole sealing bag to make the hole sealing bag set in the hole; S103, injecting water into the fracturing pipe, moving the sliding pipe relative to the fracturing pipe, so that the plug in the limiting assembly is inserted into the third hole on the sliding pipe, and the fracturing hole group corresponding to the first section of the fracturing space is in communication, water is injected into the fracturing space and fracturing is carried out; S104, increasing the water injection pressure of the fracturing pipe, the sliding pipe pushes the plug in the limiting assembly to retract, so that the sliding pipe continues to move relative to the fracturing pipe, and the plug in the limiting assembly is inserted into the next third hole on the sliding pipe, and the fracturing hole group corresponding to the second section of the fracturing space is in communication, water is injected into the fracturing space and fracturing is carried out; S105, repeating the previous step to carry out fracturing of the fracturing space section by section.

8. The coal mine hydraulic fracturing method of claim 7, wherein, The fracturing pipe has a first cavity, a second cavity, a first adjusting assembly and a second adjusting assembly; and the step of injecting water into the fracturing space and carrying out fracturing comprises: The water in the fracturing pipe enters the first chamber of the first cavity and pushes the second slider in the second adjusting assembly to move, so that the first chamber and the corresponding fracturing space are communicated to make the water flow into the fracturing space; With the fracturing space cracking and the water pressure in the second chamber of the first cavity increasing to a first threshold value, the first slider in the first adjusting assembly is pushed to move, so that the second chamber and the first chamber of the next fracturing space are communicated through the second cavity therebetween.

9. The coal mine hydraulic fracturing method of claim 8, wherein, Further comprising the following steps: S106, after completing the fracturing work of each fracturing space in the borehole in sections, releasing the water in the hole sealing bag and the fracturing pipe to unload the whole borehole; S107, resetting the sliding pipe in the whole borehole cyclic loading and unloading fracturing device, the first adjusting assembly and the second adjusting assembly; S108, repeating steps S103 to S107 to perform multiple cyclic loading and unloading fracturing operations; S109, injecting water into the hole sealing bag to make the hole sealing bag set in the borehole, injecting water into the fracturing pipe, moving the sliding pipe relative to the fracturing pipe, and inserting the plug post in the limiting assembly into the fourth hole on the sliding pipe, continuously injecting water into the first fracturing space, and connecting multiple fracturing spaces through the second cavity to achieve common fracturing of the borehole.

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