Hard roof deep hole hydraulic fracturing opener

Abstract

The utility model discloses a kind of hard roof deep hole hydraulic fracturing openers, it is related to coal mine hydraulic fracturing technical field.The opener includes opener main body, rigid spring, buffer spring and sliding sleeve;The sliding sleeve is sleeved on the opener main body, and the opener main body under the shielding of sliding sleeve is uniformly distributed with multiple circular water outlets in circumference, and filter screen structure is fixedly installed on water outlet;Rigid spring and buffer spring are double-layer nested settings, and are commonly sleeved on the opener main body, sliding sleeve one side;Spring base matched with rigid spring and buffer spring is also arranged on the opener main body.The utility model is connected sliding sleeve and water outlet integrated high-frequency self-vibration filter screen by double-spring structure, under the high pressure of fracturing hole, guarantee water outlet efficiency, improve sliding sleeve stability, prevent silt and debris from entering packer or accumulating in sealing mouth simultaneously, solve the problem of poor reset effect of packer plugging.

Description

Technical Field

[0001] This utility model relates to the field of hydraulic fracturing technology in coal mines, specifically to a hydraulic fracturing initiator for deep holes in hard roofs. Background Technology

[0002] In coal mines with hard roofs, the roof is difficult to collapse in time, resulting in large-area overhangs in the goaf. These overhangs and their sudden fracture can easily generate impact loads, large-area roof pressure, and storm surges. Stress disturbances caused by the bending and fracture of the hard roof can also induce dynamic disasters such as mine pressure. In recent years, with the development of underground drilling rigs and other technological equipment in coal mines, new hydraulic fracturing technologies combining long-distance drilling and segmented fracturing have been continuously developed. These technologies have been widely applied in areas such as large-scale pre-fracturing of hard roofs in working faces, control of strong mine pressure, roof cutting and roadway retention, and control of surrounding rock in roadways, achieving good application results.

[0003] However, during open-hole fracturing in long boreholes, as water pressure increases, the rock gradually fractures under high pressure. The sliding sleeve vibrates significantly under high pressure, resulting in unstable water flow. Large amounts of mud and debris on the outer side impact the outlet at high speed with the water flow. Under this large, unstable movement, the rock debris rubs against the inside of the sliding sleeve, gradually creating scratches or dents and gaps. When the pressure on both sides balances, pressurized mud and debris from the outer side enter the packer through these gaps. The accumulation of mud and debris at the front of the packer may prevent the packer capsule from shrinking back to its original shape after depressurization, causing it to become stuck in the rock formation or block the outlet, resulting in poor sealing at the front end during resetting. When the packer is removed or inserted, friction may cause the sliding sleeve to open slightly, or mud and debris may block the front end of the sliding sleeve, leading to poor resetting. During re-fracturing, poor sealing of the sliding sleeve can cause leakage, resulting in slow opening of the sliding sleeve, affecting overall fracturing efficiency, and ultimately causing setting failure and failure to reach the preset pressure. Utility Model Content

[0004] To address the aforementioned issues, this utility model discloses a hydraulic fracturing opener for deep holes in hardened top plates. It employs a double-spring loaded high-pressure opening valve that integrates a high-frequency self-vibrating filter and a locking device to prevent a large amount of mud and debris from entering the packer, thereby improving the sliding sleeve's reset and sealing effect, and increasing the packer's setting success rate and service life.

[0005] The present invention provides a hydraulic fracturing opener for deep holes in hardened top plates, comprising an opener body, a rigid spring, a buffer spring, and a sliding sleeve. The opener body has threaded connectors at both ends. The sliding sleeve is fitted onto the opener body, and the opener body, covered by the sliding sleeve, has multiple circumferentially distributed circular water outlets, each with a fixed filter screen. The rigid spring and the buffer spring are nested in a double layer, both fitted onto the opener body and one side of the sliding sleeve. The opener body also has a spring base matching the rigid spring and the buffer spring. A cylindrical valve seat is located below the sliding sleeve, and a valve seat sealing ring is provided on the cylindrical valve seat.

[0006] Preferably, the sliding sleeve is further provided with an arcuate groove, and a locking device is provided in the arcuate groove; the arcuate groove is provided in multiple sets corresponding to the water outlet, and each set of arcuate grooves includes two symmetrically arranged on both sides of the water outlet; the locking device includes a return body and a return spring; the return body is rotatably installed in the mounting groove opened in the arcuate groove on the surface of the opener body by a screw, the return spring is installed at the lower end of the return body on the side away from the sliding sleeve, a sealing steel plate is provided above the return spring, the sealing steel plate divides the side of the return body away from the sliding sleeve into an upper water storage chamber and a lower sealing chamber with the screw rotation point as the center, and the surface of the opener body is also provided with a water guide groove for connecting the water outlet and the upper water storage chamber.

[0007] Preferably, the upper and lower ends of the centering body are both arc-shaped structures, and the upper and lower ends of the mounting groove are arc-shaped to match the rotation path of the centering body.

[0008] Preferably, a spring positioning ball is also installed at the contact end between the reset spring and the return body.

[0009] Preferably, the filter structure includes three fixedly connected filter layers: an outer coarse-grained filter, a middle medium-grained filter, and an inner fine-grained filter.

[0010] Preferably, the filter structure further includes elastic spacers, which are fixedly connected between two adjacent filter screens and are arranged in two layers, one above the other. Each layer of elastic spacers consists of multiple spacers evenly distributed along the circumference of the filter screen. Preferably, the two layers of elastic partitions arranged vertically are staggered.

[0011] Preferably, a sealing ring is also provided between the water outlet and the filter screen structure.

[0012] Compared with the prior art, the advantages of the hydraulic fracturing opener for hardened top plates disclosed in this utility model are: This invention integrates a high-frequency self-vibrating filter and a locking device by connecting the sliding sleeve and the water outlet through a double-spring structure. Under high pressure conditions in the fracturing hole, it ensures water output efficiency, improves the stability of the sliding sleeve, and prevents mud and debris from entering the packer or accumulating at the sealing port. This solves the problems of packer blockage and poor reset effect, improves fracturing efficiency, and increases the success rate of multi-stage fracturing and sealing. Attached Figure Description

[0013] To more clearly illustrate the technical solutions of the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0014] Figure 1 This is a schematic diagram of the overall structure of a hardened top plate deep hole hydraulic fracturing opener disclosed in this utility model.

[0015] Figure 2 for Figure 1 Enlarged view of point A in the middle.

[0016] Figure 3 This is a schematic diagram of the locking device.

[0017] Figure 4 This is a schematic diagram of the filter structure.

[0018] In the diagram: 1-Threaded connector; 2-Spring base; 3-Buffer spring; 4-Rigid spring; 5-Opener body; 6-Sliding sleeve; 61-Arc groove; 7-Filter screen structure; 71-Sealing groove; 72-Sealing ring; 73-U-shaped buckle; 74-Elastic partition; 75-Outer coarse-grained filter screen; 76-Middle-layer medium-grained filter screen; 77-Inner-layer fine-grained filter screen; 8-Cylindrical valve seat; 9-Water outlet; 10-Locking device; 101-Returning body; 102-Screw; 103-Spring positioning ball; 104-Reset spring; 105-Upper water storage tank; 106-Lower sealing tank; 107-Sealing steel sheet. Detailed Implementation

[0019] The specific embodiments of this utility model will be briefly described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this utility model, not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this utility model without creative effort are within the scope of protection of this utility model.

[0020] Figures 1-4 A preferred embodiment of the present invention is shown and analyzed in detail.

[0021] like Figure 1 The illustrated deep-hole hydraulic fracturing opener for hardened top plates includes an opener body 5, a rigid spring 4, a buffer spring 3, and a sliding sleeve 6. Threaded connectors 1 are provided at both ends of the opener body 5. The sliding sleeve 6 is fitted onto the opener body 5. Four circular water outlet holes 9 are evenly distributed circumferentially on the opener body 5 under the cover of the sliding sleeve 6. A filter screen structure 7 is fixedly installed on each water outlet hole 9, and a sealing ring 72 is provided between the water outlet hole 9 and the filter screen structure 7.

[0022] like Figure 4 As shown, the filter structure 7 includes an outer coarse-grained filter 75, a middle medium-grained filter 76, and an inner fine-grained filter 77. These three layers of filters use different pore sizes to improve the filter's impact resistance, prevent clogging, and achieve better cleaning results, reducing the amount of sediment and debris entering the initiator. The three layers of filters are connected by elastic spacers 74, which are fixedly connected between adjacent filters. These spacers are arranged in two layers, one above the other. Each layer of elastic spacers 74 consists of multiple spacers evenly distributed along the circumference of the filter. The two layers of elastic spacers 74 are staggered, preventing "resonance cancellation" during micro-vibration of the filter, ensuring effective cleaning of each filter layer. Specifically, a U-shaped buckle 73 is welded to the edge of the outer coarse-grained filter 75, and the filter structure 7 is fixedly connected to the edge of the water outlet 9 via the U-shaped buckle 73. Each of the three filter layers has a sealing groove 71 for connecting with the elastic spacer 74. A sealing gasket is installed in the sealing groove 71 to fill the gap between the filter and the elastic spacer 74. The elastic spacer 74 is an arc-shaped diamond-shaped piece, which is consistent with the circular arc of the filter.

[0023] like Figure 1 As shown, the rigid spring 4 and the buffer spring 3 are nested in a double layer, coaxially stressed, and together fitted onto the main body 5 of the opener and one side of the sliding sleeve 6. The rigid spring 4 is connected to the sliding sleeve 6, and the main body 5 of the opener is also equipped with a spring base 2 that matches the rigid spring 4 and the buffer spring 3. The opener needs to open gradually as the water pressure increases. The impact response of a single spring is unstable and may cause the water outlet 9 to open suddenly, causing a sudden increase in coal seam pressure. The double-spring design is more in line with the requirements of stable fracturing. After the packer is depressurized, the sliding sleeve 6 needs to be accurately reset. The reset stability of the double spring can avoid blockage of the sand discharge channel and sealing failure caused by the sliding sleeve 6 jamming. The double springs share the load by being coaxially stressed, which reduces the force on each spring. The outer buffer spring 3 can compensate for the force deviation of the inner rigid spring 4. Even if a single spring is slightly deformed, the overall sliding sleeve 6 can still be kept balanced, ensuring the stability of the opening and closing threshold of the sliding sleeve 6. The double-spring design reduces the force on each spring, slows down fatigue damage, and meets the requirements of repeated fracturing.

[0024] like Figure 2As shown, the inner side of the sliding sleeve 6 is also provided with arc-shaped grooves 61. There are four sets of arc-shaped grooves 61 corresponding to the water outlet 9. Each set of arc-shaped grooves includes two symmetrically arranged on both sides of the corresponding water outlet 9. Each arc-shaped groove 61 is provided with a locking device 10, such as... Figure 3 As shown, the locking device 10 includes a return body 101, a return spring 104, and a spring positioning ball 103. The return body 101 is rotatably mounted in a mounting groove corresponding to the arc groove 61 on the surface of the opener body 5 via a screw 102, with the screw 102 located at the center of the return body 101. The return spring 104 is mounted on the lower end of the return body 101 away from the sliding sleeve 6, and the spring positioning ball 103 is mounted on the contact end between the return spring 104 and the return body 101. A sealing steel plate 107 is also provided above the return spring 104, dividing the side of the return body 101 away from the sliding sleeve 6 into an upper water storage chamber 105 and a lower sealing chamber 106, with the rotation point of the screw 102 as the boundary. A water guide groove is also provided on the surface of the opener body 5 for connecting the water outlet 9 and the upper water storage chamber 105. The upper and lower ends of the return body 101 are both arc-shaped structures, and the upper and lower ends of the mounting groove are arc-shaped to match the rotation path of the return body 101. The locking device 10 assists in limiting the sliding sleeve 6 with double springs. When there is no water pressure inside the sliding sleeve 6, the locking device 10 fixes the sliding sleeve 6 to prevent it from opening accidentally. After the internal pressure of the sliding sleeve 6 reaches the opening pressure, the return body 101 rotates around the screw 102, releasing the restriction on the sliding sleeve 6. Under the action of water pressure, the sliding sleeve 6 moves upward to open the water outlet 9 and release water through the fracturing. After depressurization, the sliding sleeve 6 moves downward to reset under the action of the double-layer nested springs, and the locking device 10 locks the sliding sleeve 6 again to ensure the reset effect of the sliding sleeve 6. The elastic force of the double-layer nested springs is greater than the elastic force of the reset spring 104.

[0025] like Figure 1 As shown, a cylindrical valve seat 8 is provided below the sliding sleeve 6. The cylindrical valve seat 8 is connected to the main body 5 of the opener by a thread. The sliding sleeve 6 and the cylindrical valve seat 8 are closely connected. The diameter of the cylindrical valve seat 8 is slightly larger than that of the sliding sleeve 6. After the sliding sleeve 6 is opened by pressure, it moves upward and leaves the cylindrical valve seat 8. A valve seat sealing ring 72 is provided on the cylindrical valve seat 8.

[0026] When this utility model is in operation: water flows into the main body 5 of the opener through the lower threaded connector 1, and enters the upper water storage tank 105 through the water outlet 9 and the water guide groove. The water pressure acts on the upper end of the return body 101, and the return body 101 rotates around the screw 102. The lower end presses the reset spring 104, releasing the restriction of the locking device 10 on the sliding sleeve 6. The water flows into the arc groove 61 in the sliding sleeve 6, causing the sliding sleeve 6 to overcome the resistance of the rigid spring 4 and the buffer spring 3 under the action of water pressure, move upward, leave the cylindrical valve seat 8, and open the water outlet 9. During the fracturing process, water flows through the filter screen structure 7 and out of the outlet hole 9. The pressurized water flow impacts the surface of the filter screen, and the impact force is transmitted to the elastic partition 74, causing the filter screen to vibrate. When the pressurized water flow fluctuates, the elastic partition 74 rebounds, and the filter screen vibrates at a high frequency along the circumference, and the mud and sand debris that fall into the outlet hole 9 are impacted. When the pressure is released, the sliding sleeve 6 is reset under the action of the double spring, and the locking device 10 relocks the sliding sleeve 6 to ensure the reset effect of the sliding sleeve 6.

[0027] The above description of the disclosed embodiments enables those skilled in the art to make and use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit and scope of the present invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A hydraulic fracturing initiator for deep holes in hardened roofs, characterized in that, The device includes an opening body (5), a rigid spring (4), a buffer spring (3), and a sliding sleeve (6). Both ends of the opening body (5) are provided with threaded connectors (1). The sliding sleeve (6) is fitted onto the opening body (5). The opening body (5) under the cover of the sliding sleeve (6) has multiple circular water outlet holes (9) evenly distributed around it. A filter screen structure (7) is fixedly installed on the water outlet holes (9). The rigid spring (4) and the buffer spring (3) are nested in a double layer and are fitted onto the opening body (5) and the sliding sleeve (6) on one side. The opening body (5) is also provided with a spring base (2) that matches the rigid spring (4) and the buffer spring (3). A cylindrical valve seat (8) is provided below the sliding sleeve (6), and a valve seat sealing ring (72) is provided on the cylindrical valve seat (8).

2. The hydraulic fracturing opener for a hardened top plate deep hole as described in claim 1, characterized in that, The sliding sleeve (6) is also provided with an arc groove (61), and a locking device (10) is provided in the arc groove (61); the arc groove (61) is provided in multiple sets corresponding to the water outlet (9), and each set of arc grooves includes two symmetrically arranged on both sides of the water outlet (9); the locking device (10) includes a return body (101) and a reset spring (104); the return body (101) is rotatably mounted on the surface of the opener body (5) corresponding to the arc groove (61) by a screw (102). Inside the slot, the reset spring (104) is installed at the lower end of the return body (101) away from the sliding sleeve (6). A sealing steel plate (107) is provided above the reset spring (104). The sealing steel plate (107) divides the side of the return body (101) away from the sliding sleeve (6) into an upper water storage chamber (105) and a lower sealing chamber (106) with the rotation point of the screw (102) as the center. The surface of the opener body (5) is also provided with a water guide groove for connecting the water outlet (9) and the upper water storage chamber (105).

3. The hydraulic fracturing initiator for a hardened top plate as described in claim 2, characterized in that, The upper and lower ends of the centering body (101) are both arc-shaped structures, and the upper and lower ends of the mounting groove are arc-shaped to match the rotation path of the centering body (101).

4. The hydraulic fracturing opener for a hardened top plate deep hole according to claim 2, characterized in that, The contact end between the reset spring (104) and the return body (101) is also equipped with a spring positioning ball (103).

5. A hydraulic fracturing initiator for deep holes in hardened roofs according to claim 1, characterized in that, The filter structure (7) includes three fixedly connected filter layers: an outer coarse filter (75), a middle medium filter (76), and an inner fine filter (77).

6. The hydraulic fracturing opener for a hardened top plate deep hole according to claim 5, characterized in that, The filter structure (7) also includes elastic partitions (74), which are fixedly connected between two adjacent filters and are arranged in two layers, one above the other. Each layer of elastic partitions (74) consists of multiple partitions evenly distributed along the circumference of the filter.

7. A hydraulic fracturing opener for a hardened top plate deep hole according to claim 6, characterized in that, Two layers of elastic partitions (74) are arranged alternately on the top and bottom.

8. A hydraulic fracturing initiator for a hardened top plate deep hole according to claim 5, characterized in that, A sealing ring (72) is also provided between the water outlet (9) and the filter structure (7).

Images