Rail changing type fracturing sliding sleeve

Abstract

The invention belongs to the technical field of petroleum drilling, and particularly relates to an underground fracturing rail-changing type fracturing sliding sleeve which comprises an upper connector, a sealing check block, a disc spring limiting mechanism, a rail-changing NPT screw, a spring check ring, a lower inner sliding sleeve body, a ring-mounted connector, a ring-mounted sliding block, a lower connector, a limiting lining, a fracturing sleeve body, a spring, a rail-changing sleeve body, a needle roller thrust bearing, an upper inner sliding sleeve body and a special-shaped pitching ball. According to the technical scheme, a special-shaped pitching ball enters a fracturing sliding sleeve, firstly, the pitching ball is limited and clamped by a spring limiting mechanism, and the ground pressurizes an internal flow channel; the pitching ball is limited at the moment to drive the central tubular column to axially move downwards, and the rail changing sleeve enters a rail changing stage at the moment. When the track is located on the short track, the central tubular column can reset and release the special-shaped pitching ball; when the rail is located on the long rail, the central pipe column is locked after moving downwards, the lower annular sliding block is pressed and contracted, the special-shaped pitching ball is clamped after sliding downwards, and the upper-layer ground pressurizes the interior of a well and enters a fracturing state. According to the underground fracturing rail changing type fracturing sliding sleeve, the fracturing counting efficiency is effectively improved, and counting is more accurate. And an all-metal structure is adopted, so that the underground use stability is enhanced.

Description

Technical Field

[0001] The invention relates to a fracturing tool for exploiting geological resources such as petroleum and natural gas, and in particular to a track-changing fracturing sliding sleeve, belonging to the technical field of downhole fracturing. Background Art

[0002] Among my country's oil and gas resources, unconventional oil and gas resources are large in quantity, dense in reservoirs, highly heterogeneous, and difficult to exploit. Only by forming as many artificial fractures as possible in the formation through staged fracturing technology can economical and efficient development be carried out. Staged fracturing technology has become an effective technical measure to increase oil and gas production in low-permeability and dense oil and gas reservoirs. In the actual exploitation process, it has shown remarkable results, especially when dealing with oil and gas reservoirs with multi-layer structures, large inter-layer differences, and requiring targeted transformation. This technology effectively improves the permeability and recovery rate of the reservoir by precisely controlling the fracturing operations between layers. In oilfield production, unlimited staged fracturing for unconventional reservoirs in deep wells effectively improves the seepage conditions in the oil wells and increases the production of single wells.

[0003] The fracturing sleeve is the technical key in the staged fracturing tool, and the fracturing sleeve greatly affects the fracturing operation of unconventional reservoirs. The number of fracturing operations depends on the number of installed fracturing sleeves in the well. The more installed sleeves are, the more staged fracturing layers there are. The commonly used sleeve type is the ball-throwing type, which controls the fracturing level by changing the ball size, and has a strict order from small to large for the ball-throwing sequence. Therefore, this method will lead to a limited number of sleeves that can be installed in the well, affecting the efficiency of the fracturing operation. The current mature track-changing fracturing sleeve technology is divided into hydraulic and mechanical types. Among them, the hydraulic track-changing fracturing sleeve controls the opening and closing of the sleeve through the hydraulic principle, but it is difficult to control the downhole pressure and the fracturing accuracy is not high. The mechanical track-changing fracturing sleeve uses a specific mechanical structure to realize the opening and closing of the sleeve, but requires a specific mechanical device to control the opening and closing of the sleeve, which is cumbersome to operate and inefficient. Summary of the invention

[0004] In view of the above-mentioned technical defects, the present invention provides a track-changing fracturing sleeve, which, while realizing fracturing and pressure holding, designs a simple mechanical counting mechanism, improves the stability of the counting function in complex downhole environments, and can realize accurate counting switching between the long and short tracks of the sleeve, and accurate pressure holding and fracturing.

[0005] The technical solution of the present invention is as follows: a track-changing fracturing sleeve, the internal structure of the sleeve is simply designed, the triggering mode of the sleeve is sensitive, and clear triggering feedback is obtained through pressure feedback data, so as to realize multiple full-diameter ball-dropping functions and achieve an unlimited-stage fracturing effect; the track-changing fracturing sleeve comprises a sleeve sleeve part, a sleeve core shaft part and a special-shaped ball-dropping part; the sleeve sleeve part comprises an upper joint, a track-changing NPT screw, a lower joint and a fracturing sleeve; the sleeve core shaft part comprises a sealing retaining ring, a disc spring limiting mechanism, a spring retaining ring, a lower inner sleeve, a ring groove joint, a ring-mounted slider, a limiting bushing, a spring, a track-changing sleeve, a thrust needle roller bearing and an upper inner sleeve; the disc spring limiting mechanism comprises a limiting head, a disc spring, a limiting baffle, a limiting bolt and a sealing ring; the special-shaped ball-dropping part comprises a ball head, a ball tail, a connecting bolt and a washer.

[0006] The sleeve sleeve part uses NC50 tapered threads to connect the upper joint and the fracturing sleeve, and the fracturing sleeve and the lower joint use NC50 tapered threads to connect, and the tapered thread connection achieves the purpose of sealing. The fracturing sleeve is provided with three NPT screw installation holes for track change, and the track change NPT screw and the fracturing sleeve are also threadedly connected. Three NPT screws are evenly distributed on the fracturing sleeve in the circumferential direction to ensure the stability of the track change structure. Six fracturing drilling fluid pressure relief ports are evenly distributed on the fracturing sleeve for use in fracturing operations.

[0007] The sleeve core shaft part includes a sealing retaining ring, a disc spring limiting mechanism, a spring retaining ring, a lower inner sleeve, a ring groove joint, a ring-mounted slider, a limiting bushing, a spring, a track changing sleeve, a thrust needle roller bearing, and an upper inner sleeve. The disc spring limiting mechanism includes a limiting head, a disc spring, a limiting baffle, a limiting bolt, and a sealing ring. The upper part of the upper inner sleeve is provided with three installation holes for the disc spring limiting mechanism, and the disc spring limiting mechanism is installed and limited. The limiting head in the disc spring limiting mechanism limits the position at the stepped hole in the upper inner sleeve hole, the limiting baffle applies pre-pressure to the lower disc spring, and the limiting bolt axially limits the limiting baffle in the stepped hole. The upper and lower thrust needle roller bearings axially limit the track changing sleeve, and the lower ring of the upper thrust needle roller bearing and the upper ring of the lower thrust needle roller bearing rotate synchronously with the track changing sleeve to complete the track changing function of the track changing mechanism. The track changing slot on the outside of the track changing sleeve cooperates with the track changing NPT screw to realize the internal limiting function of the track changing. The spring retaining ring is squeezed with the lower ring of the lower thrust needle roller bearing to preload the axial limit of the lower spring. The lower end of the spring in the sleeve core shaft squeezes the stepped shaft part in the fracturing sleeve to achieve axial limit. The upper end of the lower inner sleeve is connected to the upper inner sleeve through a tapered thread NC26 to ensure sealing. The bottom of the lower inner sleeve is also processed with an inclined step to buffer the instantaneous reset impact during the track change process. The bottom of the lower sleeve is connected to the ring groove joint through a thread to fix the ring groove joint. Three dovetail grooves are evenly distributed on the lower part of the ring groove joint, which cooperates with the ring-mounted slider to ensure the stability of the axial limit and radial movement trajectory of the ring-mounted slider. After being squeezed, the ring-mounted slider shrinks along the dovetail groove at the lower part of the ring-mounted joint to axially limit the special-shaped ball and perform pressure-holding fracturing operations. A limit bushing is installed between the ring groove joint and the lower inner sleeve to radially limit the ring-mounted slider.

[0008] The special-shaped ball throwing part comprises a ball head, a ball tail, a connecting bolt and a washer. The ball tail is connected to the ball head through the connecting bolt, and the washer is arranged between the connecting bolt and the ball tail.

[0009] The beneficial effects of the present invention are as follows: (1) The design of the disc spring limit mechanism enables the shaped ball part to pass through the fracturing sleeve above the fracturing layer before entering the fracturing stage. The shaped ball has the same size and realizes the full-diameter function. (2) In the design of the track-changing mechanism, the track-changing sleeve cooperates with the track-changing NPT screw to drive the fracturing mandrel to move up and down by switching the long and short tracks to trigger the fracturing function. (3) Except for some necessary rubber seals, the fracturing sleeve is a mechanical trigger structure with stable performance and little impact from the high temperature and high pressure environment underground. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Attached Figure 1 It is a structural diagram of the track-changing fracturing sleeve of the present invention; Attached Figure 2 It is a schematic diagram of the structure and arrangement of the disc spring limit mechanism; Attached Figure 3 It is the structural diagram of the track change sleeve; Attached Figure 4It is a schematic diagram of the track arrangement on the outer surface of the track change sleeve; Attached Figure 5 This is a schematic diagram of the NPT screw arrangement for the three-stage fracturing rail change; Attached Figure 6 This is a schematic diagram of the circumferential arrangement of the rail-changing NPT screws; Attached Figure 7 It is a schematic diagram of the structure of a special-shaped pitch; Attached Figure 8 It is a structural schematic diagram of a ring-mounted slider; Attached Fig. 9 It is a schematic diagram of the structure after the ring-mounted slider and the ring groove joint are installed; Attached Figure 1 Names of parts marked in: special-shaped ball throwing part; the sliding sleeve part includes 1-upper joint, 2-sealing retaining ring, 3-disc spring limiting mechanism, 4-track changing NPT screw, 5-spring retaining ring, 6-lower inner sliding sleeve, 7-ring groove joint, 8-ring mounted slider, 9-lower joint, 10-limiting bushing, 11-fracturing sleeve, 12-spring, 13-track changing sleeve, 14-thrust needle roller bearing, 15-upper inner sliding sleeve, 16-special-shaped ball throwing. DETAILED DESCRIPTION

[0011] In the present invention, for the convenience of description, the relative position relationship of each component is described according to the attached Figure 1 For example, the positional relationship between the upper and lower parts is described in the attached manual. Figure 1 direction to determine the instructions.

[0012] Refer to the attached Figure 1 , a track-changing fracturing sleeve, a track-changing fracturing sleeve includes a sleeve sleeve part, a sleeve core shaft part and a special-shaped ball-throwing part 16; the sleeve sleeve part includes an upper joint 1, a track-changing NPT screw 4, a lower joint 9, and a fracturing sleeve 11; the sleeve core shaft part includes a sealing retaining ring 2, a disc spring limiting mechanism 3, a spring retaining ring 5, a lower inner sleeve 6, a ring groove joint 7, a ring-mounted slider 8, a limiting bushing 10, a spring 12, a track-changing sleeve 13, a thrust needle roller bearing 14, and an upper inner sleeve 15; the disc spring limiting mechanism includes a limiting head, a disc spring, a limiting baffle, a limiting bolt, and a sealing ring; the special-shaped ball-throwing part 16 includes a ball head, a ball tail, a connecting bolt, and a washer.

[0013] Before the track-changing fracturing sleeve is lowered into the casing, the track-changing sleeve 13 and the track-changing NPT screw 4 are adjusted correctly according to the set level, that is, the initial fracturing level is set. After the track-changing fracturing sleeve is lowered into the casing, the mechanism body without the special-shaped ball 16 is arranged in sequence in the casing at a specified distance, and the fracturing ball stage is entered after the arrangement is completed.

[0014] Refer to the attached Figure 5The specific implementation method is described by taking the setting of three-stage fracturing as an example. Before the three-stage fracturing sleeve is lowered into the well, the position relationship between the track-changing NPT screw 4 and the track-changing sleeve 13 is set from top to bottom as follows: the first level is set to the short track of three track-changing nodes away from the long track, that is, the position number is 1; the second level is set to two track-changing nodes away from the long track, that is, the position number is 2; the third level is set to one track-changing node away from the long track, that is, the position number is 3.

[0015] Refer to the attached Figure 1 After the first-stage sliding sleeve center flow channel is injected with the shaped ball 16, the shaped ball 16 is stuck in the disc spring limit mechanism 3. The upper layer is pressurized at this time, and the compression drives the sliding sleeve core shaft to partially compress the spring 12. At this time, the track-changing NPT screw 4 changes track from position 1 to position 2. At this time, the upper layer pressure squeezes the shaped ball 16, and the shaped ball 16 squeezes the disc spring limit mechanism 3. The disc spring limit mechanism 3 is compressed and shrinks, and the shaped ball 16 passes over the disc spring limit mechanism 3 and enters the lower second-stage fracturing sliding sleeve. The shaped ball 16 enters the second-stage fracturing sliding sleeve and repeats the above steps. The track-changing NPT screw 4 changes track from 2 to position 3, and the shaped ball 16 enters the lower third-stage fracturing sliding sleeve. The shaped ball 16 enters the third-stage fracturing sleeve and repeats the above steps. The track-changing NPT screw 4 changes the track from 3 to the long track and enters the limit groove. The core shaft of the sleeve moves downward as a whole, and the bottom ring-mounted slider 8 is squeezed and contracted by the internal chamfer of the lower joint 9. Drilling fluid is introduced into the top of the central flow channel to continue pressurizing. The shaped ball 16 squeezes the disc spring limit mechanism 3, and the disc spring limit mechanism 3 is compressed and contracted. The shaped ball 16 passes over the disc spring limit mechanism 3 and continues to slide downward along the central flow channel to the ring-mounted slider 8 after contraction to reach the axial limit, and enters the pressure holding fracturing stage. The fracturing fluid enters the formation from the 6 fracturing pressure relief ports evenly distributed on the upper part of the fracturing sleeve 11, and enters the fracturing operation stage.

[0016] Refer to the attached Figure 2 The disc spring limiting mechanism 3 is arranged in three parts, which are evenly distributed in an annular manner on the upper inner sliding sleeve 15. The limiting bolt 33 connects the limiting baffle 34 with the upper inner sliding sleeve 15 to achieve radial limiting of the disc spring 32 and the limiting head 31. Figure 6 , the cross section at the limit position of the rail change NPT screw 4 is as shown in the attached Figure 6 As shown, the head of the track-changing NPT screw 4 is embedded in the track groove outside the track-changing sleeve 13, and three are evenly distributed along the circumference. Figure 8 With attached Fig. 9 The limit relationship between the ring-mounted slider 8 and the ring groove joint 7 after installation is as shown in the attached figure. Fig. 9 As shown, the connection is made through a dovetail groove, and three ring-mounted sliders are evenly distributed along the circumference.

[0017] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the patent of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. Track-changing fracturing sliding sleeve, characterized by: The internal structure of the sleeve is simple in design, the sleeve triggering method is simple, and clear triggering feedback can be obtained through pressure feedback data, so that the full-diameter function of multiple ball throwing can be realized, thereby achieving an unlimited-stage fracturing effect. The track-changing fracturing sleeve comprises a sleeve sleeve part, a sleeve core shaft part and a special-shaped ball throwing part (16); the sleeve sleeve part comprises an upper joint (1), a track-changing NPT screw (4), a lower joint (9), and a fracturing sleeve (11); the sleeve core shaft part comprises a sealing retaining ring (2), a disc spring limiting mechanism (3), a spring retaining ring (5), a lower inner sleeve (6), a ring groove joint (7), a ring-mounted slider (8), a limiting bushing (10), a spring (12), a track-changing sleeve (13), a thrust needle roller bearing (14), and an upper inner sleeve (15); the disc spring limiting mechanism comprises a limiting head, a disc spring, a limiting baffle, a limiting bolt, and a sealing ring; the special-shaped ball throwing part comprises a ball head, a ball tail, a connecting bolt, and a washer; In the track changing mechanism, the track changing NPT screw (4) is inserted into the reserved threaded hole of the fracturing sleeve, three of which are arranged circumferentially and inserted into the track changing groove of the track changing sleeve (13). The track changing NPT screw (4) realizes the long and short track switching limit function of the track changing sleeve. When the special-shaped ball-casting part (16) squeezes the disc spring limit mechanism (3), the track changing sleeve moves downward and rotates, compressing the spring (12). The track changing NPT screw (4) switches the limit position on the track groove of the track changing sleeve (13), completing the track changing. The track changing NPT screw (4) enters the track of the track changing sleeve (13). When the track in the groove is short, no fracturing is performed, and the special-shaped ball-throwing part (16) passes through the flow channel in the sleeve core shaft and enters the next-level fracturing sleeve; when the track-changing NPT screw (4) enters the track groove of the track-changing sleeve (13) with a long track, the track-changing NPT screw (4) limits the track-changing sleeve (13) in the long track, compresses the spring (12), and at the same time, the upper sleeve (15) and the lower sleeve (6) move downward along the sleeve sleeve, the annular slider (8) is squeezed and contracted by the inside of the lower joint, and the special-shaped ball-throwing part (16) is stuck, and the fracturing operation is carried out after the pressure is held.

2. According to the track-changing fracturing sleeve of claim 1, the diameter limitation of the special-shaped ball-throwing part is completed by the disc spring limiting mechanism (3), and the special-shaped ball-throwing part (16) and the disc spring limiting mechanism (3) are squeezed together to complete the pressure holding in the central flow channel inside the track-changing fracturing sleeve. When the predetermined pressure is reached, the limiting head in the disc spring limiting mechanism (3) squeezes the disc spring, and the special-shaped ball-throwing part (16) completes the diameter and enters the next level.

3. According to the track-changing fracturing sleeve of claim 1, during the track-changing process of the sleeve, the upper and lower thrust needle roller bearings (14) axially limit the track-changing sleeve (13), and the lower circle of the upper thrust needle roller bearing (14) and the upper circle of the lower thrust needle roller bearing (14) rotate synchronously with the track-changing sleeve (13), thereby completing the rotation and track-changing function of the track-changing mechanism.

4. According to the track-changing fracturing sleeve of claim 1, after the track groove on the outer surface of the track-changing sleeve (13) is changed to a long track, the track-changing sleeve (13) rotates the compression spring (12), driving the core shaft portion of the sleeve to move downward, the upper inner sleeve (15) and the lower inner sleeve (6) to move downward, and the extrusion ring-mounted slider (8) contracts at the stepped shaft inside the lower joint (9). At the same time, the special-shaped ball-throwing portion (16) is stuck at the contraction position of the ring-mounted slider (8) through the internal central flow channel of the track-changing fracturing sleeve, entering a pressure-holding state, and drilling fluid is introduced into the upper layer to increase the pressure to perform fracturing operations.

5. According to the track-changing fracturing sleeve of claim 1, in the sleeve core shaft portion, the upper sealing retaining ring (14) is limited by the upper joint (1) and the upper step of the upper inner sleeve (15), and the lower sealing retaining ring (14) is limited by the upper inner sleeve (15) and the upper thrust needle roller bearing (14).

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