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

Abstract

The invention discloses a whole-section hole circulation loading and unloading fracturing device and a coal mine hydraulic fracturing method. The whole-section hole circulating loading and unloading fracturing device comprises a fracturing pipe, hole sealing bags, a water injection pipe, a sliding pipe and a limiting assembly, a plurality of first holes are formed in the fracturing pipe, a fracturing space is defined between every two adjacent hole sealing bags, and the hole sealing bags communicate with the water injection pipe; the sliding pipe can move in an inner cavity of the fracturing pipe, one end, close to the bottom of the drill hole, of the sliding pipe is sealed, a second hole is formed in the sliding pipe, the first hole and the second hole are divided into a plurality of fracturing hole sets, each fracturing hole set comprises one first hole and one second hole, and when the first hole and the second hole in one fracturing hole set are communicated, the first hole and the second hole in the other fracturing hole set are communicated. The first holes and the second holes in the other fracturing hole groups are arranged in a staggered manner; the limiting assembly limits the position of the sliding pipe in the fracturing pipe and enables the first hole and the second hole in one fracturing hole set to be communicated. According to the method, fracturing equipment does not need to be moved, the fracturing process is simplified, and the hydraulic fracturing efficiency is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of hydraulic fracturing, and in particular relates to a full-section hole circulation loading and unloading fracturing device and a coal mine hydraulic fracturing method. Background Art

[0002] In the related technology, the fracturing device used in coal mines is a moving pipe open-hole segmented fracturing tool. After the fracturing drilling construction is completed, the fracturing device is placed in the borehole and the sealer is seated. The space between the sealing bags is the fracturing space. Since the fracturing space is small, it is impossible to fracture the entire borehole, and segmented fracturing is required. After cracks are initiated in one segment of the fracturing space, the fracturing tool is moved to fracture the next segment of the fracturing space. When cracks are initiated in the entire borehole, the entire borehole is hydraulically fractured to expand the cracks. Summary of the invention

[0003] The present invention is based on the inventor's discovery and understanding of the following facts and problems:

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

[0005] The present invention aims to solve one of the technical problems in the related art at least to a certain extent.

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

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

[0008] The full-hole cycle loading and unloading fracturing device of the embodiment of the present invention comprises:

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

[0010] Sealing bags, wherein a plurality of the sealing bags are arranged at intervals on the outside of the fracturing pipe along the extension direction of the fracturing pipe, a fracturing space is defined between two adjacent sealing bags, and the first holes are arranged in one-to-one correspondence with the fracturing spaces;

[0011] A water injection pipe, the water injection pipe is arranged in parallel with the fracturing pipe, and the sealing bag is connected to the water injection pipe;

[0012] A sliding tube, wherein the outer wall of the sliding tube is in contact with the inner wall of the fracturing tube, and the sliding tube is movable in the inner cavity of the fracturing tube, one end of the sliding tube close to the bottom of the borehole is sealed, and a plurality of second holes are provided on the sliding tube, and the plurality of the first holes and the plurality of the second holes are divided into a plurality of fracturing hole groups, and each of the fracturing hole groups includes one first hole and one second hole, and when the first hole and the second hole in one of the fracturing hole groups are connected, the first holes and the second holes in other fracturing hole groups are staggered;

[0013] A limiting assembly is provided between the fracturing tube and the sliding tube to limit the position of the sliding tube in the fracturing tube and to make the first hole and the second hole in one of the fracturing hole groups communicate with each other.

[0014] The full-hole cycle loading and unloading fracturing device of the embodiment of the present invention does not need to move the fracturing equipment during the hydraulic fracturing process of the drilled hole, thus simplifying the fracturing process and improving the efficiency of the hydraulic fracturing.

[0015] In some embodiments, a plunger hole is provided between the sealing bag near the bottom of the borehole and the inner cavity of the fracturing pipe, and the limiting assembly includes:

[0016] An insertion post, wherein the insertion post is slidably disposed in the plunger hole, an end of the insertion post close to the inner cavity has a spherical surface, and an end of the insertion post close to the sealing bag has an end plate;

[0017] a first elastic member, the first elastic member being disposed between the end plate and a side wall of the fracturing tube;

[0018] a second elastic member, the second elastic member being arranged between one end of the sliding pipe close to the bottom of the borehole and one end of the fracturing pipe close to the bottom of the borehole;

[0019] A plurality of third holes are provided on the side wall of the sliding tube, the number of the third holes being the same as the number of the fracturing hole groups, and when the plug column is inserted and limited in position with one of the third holes, the first hole and the second hole in one of the fracturing hole groups are connected.

[0020] In some embodiments, a fourth hole is provided on the side wall of the sliding tube, and when the plug column is inserted and limited in position with the fourth hole, the sliding tube and the first hole are staggered so that the first hole is directly connected with the inner cavity of the fracturing tube.

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

[0022] It also includes a first regulating component, 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 located behind it.

[0023] In some embodiments, a partition is provided in the first cavity, and the partition divides the first cavity into a first chamber and a second chamber. The first chamber is connected to the corresponding first hole. The first chamber and the second chamber are both connected to the corresponding fracturing space. Along the water injection direction of the fracturing pipe, the second cavity is connected to the second chamber of the previous first cavity and the first chamber of the next first cavity, and the first adjusting assembly is arranged in the second chamber.

[0024] In some embodiments, a fifth hole is provided between the second chamber and the corresponding fracturing space, a sixth hole is provided between the second chamber and the corresponding second cavity, the first adjusting assembly includes 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 circumference of the first slider is sealed with the inner wall of the second chamber, when the second chamber and the corresponding second cavity are disconnected, the fifth hole and the sixth hole are respectively located on both sides of the first slider, and when the second chamber and the corresponding second cavity are connected, the fifth hole and the sixth hole are located on the same side of the first slider.

[0025] In some embodiments, it also includes a second adjustment component, the second adjustment component is arranged in the first chamber, a seventh hole is arranged between the first chamber and the corresponding fracturing space, the second adjustment component includes 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 circumference of the second slider is sealed with the inner wall of the first chamber, when the first chamber and the corresponding fracturing space are disconnected, the first hole and the seventh hole are respectively located on both sides of the second slider, and when the first chamber and the corresponding fracturing space are connected, the first hole and the seventh hole are located on the same side of the second slider.

[0026] The coal mine hydraulic fracturing method according to the embodiment of the present invention comprises:

[0027] S101, construction drilling;

[0028] S102, placing the full-hole circulating loading and unloading fracturing device described in any of the above embodiments in the borehole, and injecting water into the sealing bag so that the sealing bag is sealed in the borehole;

[0029] S103, injecting water into the fracturing tube, the sliding tube moves relative to the fracturing tube, so that the plug in the limit assembly is plugged into the third hole on the sliding tube, and the fracturing hole group corresponding to the first section of the fracturing space is connected, and water is injected into the fracturing space to perform fracturing;

[0030] S104, increasing the water injection pressure of the fracturing pipe, the sliding pipe pushes the plug in the limit assembly to retract, so that the sliding pipe continues to move relative to the fracturing pipe, and the plug in the limit assembly is plugged into the next third hole on the sliding pipe, and at the same time the fracturing hole group corresponding to the second section of the fracturing space is connected, and water is injected into the fracturing space to perform fracturing;

[0031] S105, repeat the previous step to perform fracturing work in the fracturing space section by section.

[0032] In some embodiments, the fracturing pipe has a first cavity, a second cavity, a first adjustment assembly and a second adjustment assembly; the step of injecting water into the fracturing space and performing fracturing comprises:

[0033] 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 is connected to the corresponding fracturing space, and water flows into the fracturing space;

[0034] As the fractures in the fracturing space begin to occur and the water pressure in the fracturing space and the second chamber of the first chamber increases to a first threshold, the first slider in the first adjustment assembly is pushed to move so that the second chamber is connected to the first chamber of the next fracturing space through the second chamber therebetween.

[0035] In some embodiments, the following steps are also included:

[0036] S106, after completing the fracturing work of each fracturing space in the borehole section by section, releasing the water in the sealing bag and the fracturing tube to relieve the pressure of the entire borehole;

[0037] S107, resetting the sliding pipe, the first adjusting assembly, and the second adjusting assembly in the full-hole cycle loading and unloading fracturing device;

[0038] S108, repeating steps S103 to S107, performing multiple cycles of loading and unloading fracturing operations;

[0039] S109, injecting water into the sealing bag so that the sealing bag is sealed in the borehole, injecting water into the fracturing tube, the sliding tube moves relative to the fracturing tube, and the plug column in the limiting assembly is plugged into the fourth hole on the sliding tube, continuously injecting water into the first section of the fracturing space, and the multiple sections of the fracturing space are connected through the second cavity to achieve the common fracturing of the borehole. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0041] Figure 2 Schematic diagram of the structure of the sliding pipe according to the embodiment of the present invention.

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

[0043] Figure 4 It is a schematic structural diagram of a limit assembly according to an embodiment of the present invention.

[0044] Reference numerals:

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

[0046] 2. Sealing bag;

[0047] 3. Water injection pipe;

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

[0049] 5. Limiting assembly; 51. Insertion column; 52. First elastic member; 53. End plate;

[0050] 61, fifth hole; 62, sixth hole; 63, seventh hole;

[0051] 7. first adjusting component; 71. first sliding block; 72. third elastic member;

[0052] 8. Second adjusting component; 81. Second sliding block; 82. Fourth elastic member. DETAILED DESCRIPTION

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

[0054] like Figure 1 and Figure 2As shown, the full-hole circulation loading and unloading fracturing device of the embodiment of the present invention includes a fracturing tube 1, a sealing bag 2 and a water injection pipe 3, and a plurality of first holes 11 are provided on the fracturing tube 1; a plurality of sealing bags 2 are arranged at intervals on the outside of the fracturing tube 1 along the extension direction of the fracturing tube 1, and a fracturing space is defined between two adjacent sealing bags 2, and the first holes 11 are arranged one-to-one with the fracturing space; the water injection pipe 3 is arranged in parallel with the fracturing tube 1, and the sealing bag 2 is connected to the water injection pipe 3.

[0055] The sealing bag 2 is wrapped around the circumference of the fracturing pipe 1. When water is injected into the sealing bag 2 through the water injection pipe 3, the sealing bag 2 expands, so that the outer wall surface of the sealing bag 2 abuts and seals against the inner wall of the borehole, and a fracturing space is formed between two adjacent sealing bags 2. When water is injected into the fracturing space through the fracturing pipe 1, the fracturing space can be fracturing.

[0056] The full-section hole circulation loading and unloading fracturing device of the embodiment of the present invention also includes a sliding tube 4 and a limiting assembly 5. The outer wall of the sliding tube 4 is in contact with the inner wall of the fracturing tube 1, and the sliding tube 4 is movable in the inner cavity of the fracturing tube 1. The end of the sliding tube 4 close to the bottom of the borehole is sealed. A plurality of second holes 41 are provided on the sliding tube 4. 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 includes a first hole 11 and a second hole 41. When the first hole 11 and the second hole 41 in one fracturing hole group are connected, the first holes 11 and the second holes 41 in other fracturing hole groups are staggered.

[0057] The limiting assembly 5 is disposed between the fracturing tube 1 and the sliding tube 4 to limit the position of the sliding tube 4 in the fracturing tube 1 and to connect the first hole 11 and the second hole 41 in one of the fracturing hole groups.

[0058] During operation, in order to perform fracturing operations on multiple fracturing spaces section by section, a slide tube 4 is arranged in the fracturing tube 1, and the slide tube 4 can slide in the fracturing tube 1. The outer wall of the slide tube 4 is sealed with the inner wall of the fracturing tube 1. When one of the second holes 41 on the slide tube 4 is aligned with one of the first holes 11 on the fracturing tube 1, the water in the fracturing tube 1 can flow into the fracturing space through the connected fracturing hole group. The embodiment of the present invention controls the relative position between the fracturing tube 1 and the slide tube 4 through the limit assembly 5, thereby ensuring that the slide tube 4 and the fracturing tube 1 are accurately aligned and the first hole 11 and the second hole 41 in one group of fracturing hole groups are connected, which is convenient for performing fracturing work section by section.

[0059] The full-hole cycle loading and unloading fracturing device of the embodiment of the present invention does not need to move the fracturing equipment during the hydraulic fracturing process of the drilled hole, thus simplifying the fracturing process and improving the efficiency of the hydraulic fracturing.

[0060] like 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 tube 1, and the limiting assembly 5 includes a column 51, a first elastic member 52 and a second elastic member 44. The column 51 is slidably arranged in the plunger hole, and the end of the column 51 near the inner cavity has a spherical surface, and the end of the column 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 tube 1, and the second elastic member 44 is arranged between the end of the sliding tube 4 near the bottom of the borehole and the end of the fracturing tube 1 near the bottom of the borehole; a plurality of third holes 42 are provided on the side wall of the sliding tube 4, and the number of the third holes 42 is the same as the number of the fracturing hole groups. When the column 51 is inserted and limited with one of the third holes 42, the first hole 11 and the second hole 41 in one of the fracturing hole groups are connected.

[0061] The column 51 is arranged in the plunger hole and can move axially along 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 column 51 and the side wall of the fracturing tube 1, which can provide a reset force for the column 51, so that the column 51 is in a reset state when not working, and does not interfere with other components.

[0062] The sealing bag 2 needs to be sealed first, so a certain water pressure is always maintained in the sealing bag 2. The water pressure in the sealing bag 2 acts on the plug column 51, causing the plug column 51 to move toward the center of the fracturing tube 1. When water is injected into the fracturing tube 1, the slide tube 4 moves under the action of the water in the fracturing tube 1. When the slide tube 4 pushes to the spherical surface of the plug column 51, the force of the water pressure in the fracturing tube 1 on the slide tube 4 can cause the slide tube 4 to push the plug column 51 back. When the plug column 51 is aligned with the third hole 42 on the slide tube 4 closest to the bottom of the borehole, the plug column 51 extends out and is inserted into the third hole 42. At the same time, the first hole 11 and the second hole 41 at the port closest to the borehole are aligned and connected. At this time, the water pressure in the fracturing tube 1 can be adjusted to prevent the slide tube 4 from continuing to move. The water in the fracturing tube 1 will enter the first section of the fracturing space for fracturing operations.

[0063] When it is necessary to carry out fracturing operation in the next section of the fracturing space, the water pressure in the fracturing tube 1 is increased, and the force exerted by the sliding tube 4 on the spherical surface of the plug column 51 can retract the plug column 51 again until the plug column 51 is inserted into the next third hole 42 on the sliding tube 4. At this time, the first hole 11 and the second hole 41 in the fracturing hole group corresponding to the second section of the fracturing space are connected, and the water in the fracturing tube 1 will enter the first section of the fracturing space for fracturing operation.

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

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

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

[0067] That is to say, the water in the fracturing pipe 1 first enters the first cavity 12 through the first hole 11, and then flows into the fracturing space from the first cavity 12. When the water pressure in the fracturing space increases to the preset pressure, the first regulating component 7 can be activated to connect the first cavity 12 and the second cavity 13 located behind it. Part of the water in the first cavity 12 will flow into the first cavity 12 corresponding to the latter fracturing space through the second cavity 13. At this time, the water pressure in the former fracturing space is reduced, and the fracturing operation of the former fracturing space is completed. By moving the sliding pipe 4, the latter fracturing space is fractured, and the former fracturing space is depressurized.

[0068] The embodiment of the present invention can make two adjacent fracturing spaces relatively independent during normal operation by setting the first chamber 12 and the second chamber 13, and can make the two adjacent fracturing spaces connected after the fracturing of the previous fracturing space is completed, so as to relieve the pressure of the previous fracturing space.

[0069] In some embodiments, the first cavity 12 has a partition 123, which 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, and the first chamber 121 and the second chamber 122 are both 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 is connected to the second chamber 122 of the previous first cavity 12 and the first chamber 121 of the next first cavity 12, and the first adjusting assembly 7 is arranged in the second chamber 122.

[0070] That is to say, the first chamber 12 is divided into a first chamber 121 and a second chamber 122, and 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 tube 1 first enters the first chamber 121 through the first hole 11, and the water in the first chamber 121 enters the fracturing space for fracturing operations. The fracturing space is connected to the first chamber 121 and the second chamber 122. Therefore, the water pressure in 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 the preset pressure, the first regulating component 7 will act and connect the second chamber 122 and the second chamber 13 adjacent thereto, so that part of the water enters the first chamber 121 of the first chamber 12 corresponding to the latter fracturing space.

[0071] Furthermore, a fifth hole 61 is provided between the second chamber 122 and the corresponding fracturing space, a sixth hole 62 is provided between the second chamber 122 and the corresponding second cavity 13, the first adjusting assembly 7 includes 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 circumference of the first slider 71 is sealed with the inner wall of the second chamber 122, when the second chamber 122 and the corresponding second cavity 13 are disconnected, the fifth hole 61 and the sixth hole 62 are respectively located on both sides of the first slider 71, and when the second chamber 122 and the corresponding second cavity 13 are connected, 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 both 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 pass through the second cavity 13 into the first chamber 121 corresponding to the next fracturing space.

[0073] When the water pressure in the fracturing space reaches the preset pressure, the water pressure in the fracturing space is the same as that in the second chamber 122, and 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 corresponding second chamber 122 and the second cavity 13 between the two fracturing spaces.

[0074] Furthermore, the full-section hole circulation loading and unloading fracturing device also includes a second adjusting component 8, which is arranged in the first chamber 121, and a seventh hole 63 is provided between the first chamber 121 and the corresponding fracturing space. The second adjusting component 8 includes a second slider 81 and a fourth elastic member 82, and the second slider 81 is arranged in the corresponding first chamber 121, and the fourth elastic member 82 is arranged between the second slider 81 and the inner wall of the first chamber 121, and the circumference of the second slider 81 is sealed with the inner wall of the first chamber 121. When the first chamber 121 and the corresponding fracturing space are disconnected, the first hole 11 and the seventh hole 63 are respectively located on both sides of the second slider 81, and when the first chamber 121 and the corresponding fracturing space are connected, the first hole 11 and the seventh hole 63 are located on the same side of the second slider 81.

[0075] The working principle is the same as that of the first adjustment component 7. Under normal conditions, under the action of the fourth elastic member 82, the first hole 11 and the seventh hole 63 are located on both sides of the second slider 81, the first hole 11 and the seventh hole 63 are not connected, and the water in the fracturing tube 1 cannot enter the fracturing space through the first chamber 121.

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

[0077] The first regulating component 7 and the second regulating component 8 can be driven to move according to the magnitude of the water pressure, thereby achieving conduction between adjacent chambers under a preset pressure, thereby reducing the difficulty of control and making the fracturing process more practical.

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

[0079] In some embodiments, a fourth hole 43 is provided on the side wall of the sliding tube 4 . When the plug post 51 is inserted into the fourth hole 43 and limited, the sliding tube 4 and the first hole 11 are staggered so that the first hole 11 is directly connected to the inner cavity of the fracturing tube 1 .

[0080] It should be understood that when the column 51 is inserted into the first thread hole and limited, at least one first hole 11 on the fracturing tube 1 is completely offset from the sliding tube 4, and the water in the fracturing tube 1 can be directly injected into the corresponding fracturing space through the first hole 11, and multiple fracturing spaces are connected through multiple second cavities 13, so as to facilitate the simultaneous fracturing operation of multiple fracturing spaces in the entire borehole.

[0081] The coal mine hydraulic fracturing method according to the embodiment of the present invention comprises:

[0082] S101. Construction drilling: Specifically, construction of fracturing drilling holes in a tunnel or on the ground along the designed parameters using a drilling rig.

[0083] S102, placing the full-section hole circulation loading and unloading fracturing device in any of the above embodiments in the borehole, and injecting water into the sealing bag to seal the sealing bag in the borehole.

[0084] After the full-hole cycle loading and unloading fracturing device is arranged in the borehole, the water injection pipe is connected to the pump group, and the water flows into the sealing bag, which expands and seals. At this time, there is a plug column in the sealing bag near the bottom of the borehole. Under the action of the water pressure inside the sealing bag, the plug column is inserted into the fracturing pipe.

[0085] S103, inject water into the fracturing tube, and move the slide tube relative to the fracturing tube so that the plug column in the limit assembly is plugged into the third hole on the slide tube, and at the same time the fracturing hole group corresponding to the first section of the fracturing space is connected, and water is injected into the fracturing space to perform fracturing.

[0086] Movement of sliding tube: Connect the fracturing tube to the pump group, water flows into the fracturing tube, the pressure inside the tube rises, and the sliding tube is pushed by the water to move toward the bottom of the borehole relative to the fracturing tube. The sliding tube contacts the plug column. Since the end of the plug column is a smooth hemispherical shape, when the driving force acting on the sliding tube is large enough, the plug column can be pushed back.

[0087] As the sliding tube continues to move, the third hole on the sliding tube closest to the bottom of the borehole corresponds to the plug column, and at the same time, the second hole closest to the borehole opening corresponds to the first hole on the fracturing tube closest to the borehole opening (as shown in a1 and b1 in the figure). Part of the water in the fracturing tube will flow to the first section of the fracturing space, and the internal pressure of the fracturing tube will decrease. At the same time, the plug column is inserted into the corresponding third hole (T1 shown in the figure), and the sliding tube stops moving.

[0088] When the fracturing tube has a first cavity, a second cavity, a first adjusting assembly and a second adjusting assembly, water in the fracturing tube 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 is connected to the corresponding fracturing space, and water flows into the fracturing space; as the cracks in the fracturing space begin to crack and the water pressure in the fracturing space and the second chamber of the first cavity increases to a first threshold value, the first slider in the first adjusting assembly is pushed to move, so that the second chamber is connected to the first chamber of the next section of the fracturing space through the second cavity therebetween.

[0089] That is to say, the water in the fracturing tube first enters the first chamber, and the water flow converges in the first chamber corresponding to the first section of the fracturing space, and 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 and the seventh hole corresponding to the first section of the fracturing space are located on the same side of the second slider), and the water flows into the first section of the fracturing space, and the water in the first section of the fracturing space will also flow into the second chamber. At the same time of fracturing and water injection in this section of the fracturing space, as the cracks in the fracturing space begin to crack and the water pressure in the second chamber of the fracturing space and the first chamber increases to a first threshold value, the first slider in the first adjusting assembly will be pushed to move, so that the second chamber is connected to the first chamber of the next section of the fracturing space through the second chamber between the two, and part of the water will flow to the first chamber corresponding to the next section of the fracturing space.

[0090] S104, increasing the water injection pressure of the fracturing tube, the sliding tube pushes the plug column in the limit assembly to retract, so that the sliding tube continues to move relative to the fracturing tube, and the plug column in the limit assembly is plugged into the next third hole on the sliding tube, and at the same time 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 increasing the water injection pressure of the fracturing tube, the force acting on the sliding tube can push the plug column to retract, so that the sliding tube continues to move toward the bottom of the borehole, and then the plug column is plugged into another third hole (T2) on the sliding tube. 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, water no longer enters the first section of the fracturing space, the internal pressure of the first section of the fracturing space continues to decrease, and the pressure of the second section of the fracturing space increases, the first regulating assembly and the second regulating assembly corresponding to the first section of the fracturing space are reset, water no longer flows between the first section of the fracturing space and the second section of the fracturing space, 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. Repeat step 104, and then the third fracturing space, the fourth fracturing space, ... the nth fracturing space can be fractured section by section.

[0093] Furthermore, 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 sealing bag and the fracturing tube to relieve the pressure of the entire borehole.

[0095] 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.

[0096] After a cycle of loading and unloading in the n-stage fracturing space, the surrounding rock of the borehole is damaged. The water injection pipe is opened to release the water pressure in the sealing bag, the sealing bag shrinks, the fracturing space is connected, the water flow is lost, and the whole section is depressurized. At the same time, the plug column shrinks, releasing the water flow in the fracturing pipe, the sliding pipe returns to the initial state, and each first adjustment component and each second adjustment component are also reset.

[0097] S108, repeating steps S103 to S107, performing multiple cycles of loading and unloading fracturing operations. Performing cyclic loading and unloading in the entire fracturing hole, so that the rock mass around the borehole is damaged and the fracture initiation pressure is reduced.

[0098] S109, inject water into the sealing bag to seal the sealing bag in the borehole, inject water into the fracturing tube, move the sliding tube relative to the fracturing tube, and connect the plug column in the limiting assembly with the fourth hole on the sliding tube, continuously inject water into the first section of the fracturing space, and connect multiple sections of the fracturing space through the second cavity to achieve common fracturing of the borehole.

[0099] After the fracturing operation of the entire fracturing hole is cyclically loaded and unloaded, the sealing bag is sealed, 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 plug column is plugged into the fourth hole on the sliding pipe, the sliding pipe no longer moves, and the pressure of water entering the first fracturing space continues to increase. The first regulating component and the second regulating component corresponding to the first fracturing space are activated, and water is allowed to flow into the subsequent fracturing spaces section by section until the nth fracturing space. The pressures of the n fracturing spaces are the same, and the borehole is fractured together.

[0100] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

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

[0102] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection, an electrical connection, or communication with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0103] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0104] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0105] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A full-hole cycle loading and unloading fracturing device, characterized in that: include: A fracturing pipe, wherein a plurality of first holes are provided on the fracturing pipe; Sealing bags, wherein a plurality of the sealing bags are arranged at intervals on the outside of the fracturing pipe along the extension direction of the fracturing pipe, a fracturing space is defined between two adjacent sealing bags, and the first holes are arranged in one-to-one correspondence with the fracturing spaces; A water injection pipe, the water injection pipe is arranged in parallel with the fracturing pipe, and the sealing bag is connected to the water injection pipe; A sliding tube, wherein the outer wall of the sliding tube is in contact with the inner wall of the fracturing tube, and the sliding tube is movable in the inner cavity of the fracturing tube, one end of the sliding tube close to the bottom of the borehole is sealed, and a plurality of second holes are provided on the sliding tube, and the plurality of the first holes and the plurality of the second holes are divided into a plurality of fracturing hole groups, and each of the fracturing hole groups includes one first hole and one second hole, and when the first hole and the second hole in one of the fracturing hole groups are connected, the first holes and the second holes in other fracturing hole groups are staggered; A limiting assembly is provided between the fracturing tube and the sliding tube to limit the position of the sliding tube in the fracturing tube and to make the first hole and the second hole in one of the fracturing hole groups communicate with each other.

2. The full-hole cycle loading and unloading fracturing device according to claim 1 is characterized in that: A plunger hole is provided between the sealing bag near the bottom of the borehole and the inner cavity of the fracturing pipe, and the limiting assembly includes: An insertion post, wherein the insertion post is slidably disposed in the plunger hole, an end of the insertion post close to the inner cavity has a spherical surface, and an end of the insertion post close to the sealing bag has an end plate; a first elastic member, the first elastic member being disposed between the end plate and a side wall of the fracturing tube; a second elastic member, the second elastic member being arranged between one end of the sliding pipe close to the bottom of the borehole and one end of the fracturing pipe close to the bottom of the borehole; A plurality of third holes are provided on the side wall of the sliding tube, the number of the third holes being the same as the number of the fracturing hole groups, and when the plug column is inserted and limited in position with one of the third holes, the first hole and the second hole in one of the fracturing hole groups are connected.

3. The full-hole cycle loading and unloading fracturing device according to claim 2 is characterized in that: The side wall of the sliding tube is provided with a fourth hole. When the insertion column is inserted into the fourth hole and limited, the sliding tube and the first hole are arranged in a staggered manner so that the first hole is directly connected to the inner cavity of the fracturing tube.

4. The full-hole cycle loading and unloading fracturing device according to any one of claims 1 to 3, characterized in that: A first cavity is provided on the side wall of the fracturing pipe section corresponding to each of the fracturing spaces, and a second cavity is provided on the side wall of the fracturing pipe section between two adjacent fracturing spaces, the first cavity is communicated with the corresponding first hole and the corresponding fracturing space, and the second cavity is communicated with two adjacent first cavities; It also includes a first regulating component, 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 located behind it.

5. The full-hole cycle loading and unloading fracturing device according to claim 4 is characterized in that: The first cavity has a partition plate therein, which divides the first cavity into a first chamber and a second chamber. The first chamber is connected to the corresponding first hole. The first chamber and the second chamber are both connected to the corresponding fracturing space. Along the water injection direction of the fracturing pipe, the second cavity is connected to the second chamber of the previous first cavity and the first chamber of the next first cavity. The first regulating assembly is arranged in the second chamber.

6. The full-hole cycle loading and unloading fracturing device according to claim 5 is characterized in that: A fifth hole is provided between the second chamber and the corresponding fracturing space, a sixth hole is provided between the second chamber and the corresponding second cavity, the first adjusting assembly includes 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 circumference of the first slider is sealed with the inner wall of the second chamber, when the second chamber and the corresponding second cavity are disconnected, the fifth hole and the sixth hole are respectively located on both sides of the first slider, and when the second chamber and the corresponding second cavity are connected, the fifth hole and the sixth hole are located on the same side of the first slider.

7. The full-hole cycle loading and unloading fracturing device according to claim 6 is characterized in that: It also includes a second adjustment component, which is arranged in the first chamber, and a seventh hole is arranged between the first chamber and the corresponding fracturing space. The second adjustment component includes a second slider and a fourth elastic member, and the second slider is arranged in the corresponding first chamber, and the fourth elastic member is arranged between the second slider and the inner wall of the first chamber. The circumference of the second slider is sealed with the inner wall of the first chamber. When the first chamber and the corresponding fracturing space are disconnected, the first hole and the seventh hole are respectively located on both sides of the second slider. When the first chamber and the corresponding fracturing space are connected, the first hole and the seventh hole are located on the same side of the second slider.

8. A coal mine hydraulic fracturing method, characterized in that: include: S101, construction drilling; S102, placing the full-hole cycle loading and unloading fracturing device according to any one of claims 1 to 7 in the borehole, and injecting water into the sealing bag so that the sealing bag is sealed in the borehole; S103, injecting water into the fracturing tube, the sliding tube moves relative to the fracturing tube, so that the plug in the limit assembly is plugged into the third hole on the sliding tube, and the fracturing hole group corresponding to the first section of the fracturing space is connected, and water is injected into the fracturing space to perform fracturing; S104, increasing the water injection pressure of the fracturing pipe, the sliding pipe pushes the plug in the limit assembly to retract, so that the sliding pipe continues to move relative to the fracturing pipe, and the plug in the limit assembly is plugged into the next third hole on the sliding pipe, and at the same time the fracturing hole group corresponding to the second section of the fracturing space is connected, and water is injected into the fracturing space to perform fracturing; S105, repeat the previous step to perform fracturing work in the fracturing space section by section.

9. The coal mine hydraulic fracturing method according to claim 8, characterized in that: The fracturing pipe has a first cavity, a second cavity, a first adjustment assembly and a second adjustment assembly; the steps of injecting water into the fracturing space and performing fracturing include: 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 connected and water flows into the fracturing space; As the fractures in the fracturing space begin to occur and the water pressure in the fracturing space and the second chamber of the first chamber increases to a first threshold, the first slider in the first adjustment assembly is pushed to move so that the second chamber is connected to the first chamber of the next fracturing space through the second chamber therebetween.

10. The coal mine hydraulic fracturing method according to claim 9, characterized in that: The following steps are also included: S106, after completing the fracturing work of each fracturing space in the borehole section by section, releasing the water in the sealing bag and the fracturing tube to relieve the pressure of the entire borehole; S107, resetting the sliding pipe, the first adjusting assembly, and the second adjusting assembly in the full-hole cycle loading and unloading fracturing device; S108, repeating steps S103 to S107, performing multiple cycles of loading and unloading fracturing operations; S109, injecting water into the sealing bag so that the sealing bag is sealed in the borehole, injecting water into the fracturing tube, the sliding tube moves relative to the fracturing tube, and the plug column in the limiting assembly is plugged into the fourth hole on the sliding tube, continuously injecting water into the first section of the fracturing space, and the multiple sections of the fracturing space are connected through the second cavity to achieve the common fracturing of the borehole.

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