A card distance elongation adjuster for oil and gas well fracturing

Abstract

This invention relates to the field of oil and gas field production engineering technology, and particularly to a clamping distance adjustment device for oil and gas well fracturing. It mainly solves the problem that existing fracturing systems can only connect to one clamping distance per trip, making well and layer selection difficult. The clamping distance adjustment device for oil and gas well fracturing includes an upper connector (1), the lower end of which is connected to a central tube (4). The central tube (4) is externally slidably connected to an outer sleeve (5). The lower end of the central tube (4) is internally threaded with a spring claw (7). The external boss of the spring claw (7) engages with the internal boss on the inner wall of the outer sleeve (5). A sliding sleeve (8) is provided inside the spring claw (7). A lower connector (9) is provided at the lower end of the spring claw (7). The sliding sleeve (8) and the lower connector (9) are connected by a shear pin (11). This clamping distance adjustment device for oil and gas well fracturing can be connected to the fracturing tubing string and can adjust the clamping distance even without raising the tubing string downhole, adapting to changes in reservoir thickness and enabling efficient development of thin and poor reservoirs.

Description

Technical Field

[0001] This invention relates to the field of oil and gas field production engineering technology, specifically to a clamping distance extension adjuster for fracturing oil and gas wells. Background Technology

[0002] With the deepening development of most oilfields both domestically and internationally, easily exploitable reservoirs with good permeability and large thickness are becoming increasingly scarce. However, the remaining reserves of Class II and III thin and poor-permeability reservoirs remain abundant. Most of these thin and poor-permeability reservoirs have low or ultra-low permeability and require fracturing measures, especially some old wells that require repeated fracturing stimulation. At the same time, these reservoirs have significant differences in vertical thickness. Currently, the commonly used fracturing technology is the coiled tubing double-sealed drag fracturing process (also known as cross-packing fracturing technology). The main tubing structure of this technology consists of two packers connected at the front, with a fixed spacing (i.e., packer spacing) between the two packers according to the reservoir distribution. However, a single tubing string can only connect one packer spacing. If the fracturing packer spacing needs to be adjusted, the entire well tubing string needs to be taken out to the surface for replacement and then run back into the wellbore. A single tubing string cannot meet the needs of fine stimulation of small layers with large thickness differences, making well and layer selection difficult, with poor adaptability, low efficiency, and high cost. Therefore, a tool is needed that can adjust the clamping distance using a ball-dropping sliding sleeve without raising the tubing string downhole, to adapt to changes in reservoir thickness and achieve efficient development of Class II and III reservoirs. Summary of the Invention

[0003] To overcome the shortcomings of existing fracturing methods that only allow one type of clamping distance per trip and make well and layer selection difficult, this invention provides a clamping distance extension adjuster for oil and gas well fracturing. This clamping distance extension adjuster can be connected to the fracturing tubing string and can adjust the clamping distance without raising the tubing string downhole, adapting to changes in reservoir thickness and enabling efficient development of thin and poor reservoirs.

[0004] The technical solution of the present invention is: a clamping distance extension adjuster for fracturing oil and gas wells, comprising an upper connector, a central tube internally connected to the lower end of the upper connector, an outer sleeve slidably connected to the outside of the central tube, a spring claw threadedly connected to the lower end of the central tube, an outer boss of the spring claw cooperating with an inner boss on the inner wall of the outer sleeve, a sliding sleeve provided inside the spring claw, a lower connector provided at the lower end of the spring claw, and the sliding sleeve and the lower connector being connected by a shear pin.

[0005] Furthermore, the lower end of the central tube is provided with a locking step, and the upper end of the outer sleeve is provided with a first inner boss, the locking step cooperating with the first inner boss.

[0006] Furthermore, the outer circumferential surface of the locking step contacts the inner wall of the outer sleeve, and a sealing ring B is provided at the contact point.

[0007] Furthermore, the inner wall of the outer casing is provided with a second inner boss in the middle, which cooperates with the outer boss of the spring claw. When the second inner boss cooperates with the outer boss of the spring claw, the first inner boss is located above the locking step.

[0008] Furthermore, the lower part of the inner wall of the outer jacket is provided with a third inner boss, which cooperates with the outer boss of the lower connector.

[0009] Furthermore, the lower connector is located inside the outer casing, and the lower connector and the outer casing are connected by threads and are provided with a lower anti-rotation pin.

[0010] Furthermore, the upper sidewall of the first inner protrusion on the outer casing has several axial slits.

[0011] Furthermore, the upper end of the spring claw is a cylinder, and the lower end of the cylinder is a number of circumferentially distributed individual spring claws with gaps between them.

[0012] Furthermore, the upper connector is threadedly connected to the central tube and is provided with an upper anti-rotation pin.

[0013] Furthermore, during fracturing operations, when the clamping distance needs to be adjusted for the next target layer, a ball is dropped at the wellhead to apply pressure, shearing pins are cut, the sliding sleeve moves down to release the spring claws, thereby causing the outer sleeve and the tubing below to slide down until the first inner boss on the outer sleeve is locked on the clamping step of the central tube, thus realizing the clamping distance change.

[0014] This invention offers the following advantages: By adopting the above-mentioned scheme, an extension regulator of appropriate length is selected based on the reservoir thickness distribution and spacing adjustment requirements. This regulator, connected between the upper and lower packers, acts as a spacing-adjusting tubing. It is delivered to the target formation via fracturing tubing. When the next target formation requires spacing adjustment, a ball is simply dropped at the wellhead to release the spring claw by removing the sliding sleeve. The outer sleeve and the tubing below it then slide down together, achieving the spacing change. The sliding distance can be pre-designed according to the reservoir thickness, thereby achieving the effect of spacing adjustment and adapting to the requirements of fine-tuning of target formations of different thicknesses.

[0015] The overall regulator allows for smooth fracturing operations while maintaining the initial clamping distance. When the reservoir thickness increases and the packer spacing between the two packers needs adjustment, conventional techniques currently require pulling the entire tubing string to the surface, increasing the tubing length between the two packers, and then re-running the entire tubing string to the predetermined position. However, this application uses an extension regulator to replace part of the clamping tubing. Only a ball needs to be dropped at the wellhead, a predetermined pressure applied to shear the sliding sleeve pin, and the sliding sleeve removed to release the elasticity of the spring claw. The central tube and outer sleeve move relative to each other under pressure to the predetermined position, achieving clamping distance adjustment without lifting the tubing string. This adapts to fine-tuning of small layers with large thickness differences, enabling efficient development of thin and poor reservoirs. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of the present invention.

[0017] In the diagram, 1-upper connector, 2-sealing ring A, 3-upper anti-rotation pin, 4-center tube, 41-locking step, 5-outer sleeve, 51-first inner boss, 52-second inner boss, 53-third inner boss, 6-sealing ring B, 7-spring claw, 8-sliding sleeve, 9-lower connector, 10-sealing ring C, 11-shearing pin, 12-sealing ring D, 13-lower anti-rotation pin. Detailed Implementation

[0018] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. The technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] In the description of this invention, it is necessary to understand that the orientations or positional relationships indicated by terms such as "upper," "lower," "left," "right," "inner," "outer," "top," and "bottom" are based on the orientations or positional relationships shown in the accompanying drawings. They are intended only to facilitate the description of this invention and to simplify the description, and are not intended to indicate or imply that the components referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0020] Depend on Figure 1 As shown, a clamping distance adjustment device for oil and gas well fracturing includes an upper connector 1. A central tube 4 is internally threaded to the lower end of the upper connector 1, and a sealing ring A2 is provided between them. An upper anti-rotation pin 3 is provided between the side wall of the upper connector 1 and the outer wall of the central tube 4 to prevent relative rotation between them. An outer sleeve 5 is slidably connected to the outside of the central tube 4. The outer sleeve 5 is located below the upper connector 1. When the adjustment device is in its initial position, the upper end face of the outer sleeve 5 is in contact with the lower end face of the upper connector 1.

[0021] The lower end of the central tube 4 is internally threaded with a spring claw 7. The upper end of the spring claw 7 is a cylindrical body, the inner wall of which is flush with the inner wall of the central tube 4. The upper end of the cylindrical body has an external thread, and the lower end of the cylindrical body consists of several circumferentially distributed individual spring claws with gaps between them. This allows the spring claws to be elastic in the radial direction. The number of individual spring claws and the size of the gaps between them ensure both elasticity and strength. Each spring claw 7 has a boss on its exterior, which mates with an inner boss on the inner wall of the outer sleeve 5, thereby fixing the outer sleeve 5 axially upward. The root of the spring claw boss has a rounded transition to reduce stress concentration and ensure the strength of the spring claw 7. The spring claw 7 is made of high-performance spring steel, ensuring good elasticity and smooth movement before and after releasing the outer sleeve 5.

[0022] The spring claw 7 has a sliding sleeve 8 inside, with a ball seat at the upper end and an inclined surface that mates with the steel ball. When the sliding sleeve 8 is inside the spring claw 7, it pushes the spring claw outward, causing the outer protrusion of the spring claw 7 to engage with the inner protrusion on the inner wall of the outer sleeve 5, thus axially limiting the outer sleeve 5 and preventing it from sliding downward. When the ball is thrown from above, it lands on the sliding sleeve 8 and is compressed. After sliding down under pressure, the sliding sleeve 8 releases its support for the spring claw 7, causing the spring claw to retract inward and detach from the outer sleeve 5.

[0023] The lower end of the spring claw 7 is provided with a lower connector 9. When the adjuster is in the initial position, the upper end face of the lower connector 9 is in contact with the lower end face of the spring claw 7. The lower end of the sliding sleeve 8 is located inside the lower connector 9, and a sealing ring D12 is provided between the two. The sliding sleeve 8 and the lower connector 9 are connected by a number of shear pins 11. The shear pins 11 limit the axial movement of the sliding sleeve 8. When the pressure on the shear pin 11 is greater than its shearing force, the shear pin 11 is cut off, and the sliding sleeve 8 falls.

[0024] The lower connector 9 is located inside the outer sleeve 5, and the lower connector 9 and the outer sleeve 5 are connected by threads. A lower anti-rotation pin 13 is provided between them to prevent relative rotation. The outer surface of the lower connector 9 has a protruding step, which engages with a boss on the inner wall of the outer sleeve 5 to limit the axial movement of the outer sleeve 5 and prevent it from falling downwards. Furthermore, because the lower connector 9 and the outer sleeve 5 are connected by threads, they can move axially together. Simultaneously, a sealing ring C10 is provided between the outer wall of the lower connector 9 and the outer sleeve 5.

[0025] To further understand the structure of this regulator, the structure of the central tube 4 and the outer sleeve 5 will be described in detail below: The lower end of the central tube 4 has a protruding locking step 41 on its outer side. The upper end of the outer sleeve 5 has a first inner boss 51, a second inner boss 52, and a third inner boss 53 arranged sequentially from top to bottom. The first inner boss 51 mates with the locking step 41, and the inner side of the outer sleeve 5 above the first inner boss 51 contacts the outer wall of the central tube 4. At the same time, the outer circumferential surface of the central tube 4 below the locking step 41 contacts the inner wall of the outer sleeve 5, and a sealing ring B6 is provided at the contact point. Several through-cut slits are opened on the upper side wall of the first inner boss 51 on the outer sleeve 5. The size of the slits is sufficient to prevent sand from entering, and the number of slits meets the normal exhaust requirements during rapid relative movement between the central tube 4 and the outer sleeve 5.

[0026] The second inner protrusion 52 of the outer sleeve 5 is an inclined surface, which cooperates with the outer protrusion of the spring claw 7. When the spring claw 7 is pushed outward by the sliding sleeve 8, the outer protrusion of the spring claw 7 can limit the axial movement of the outer sleeve 5. When the sliding sleeve 8 slides down, the spring claw 7 retracts inward, and its outer protrusion separates from the second inner protrusion 52, allowing the outer sleeve 5 to move axially upward and downward. The second inner protrusion 52 is an inclined surface, which makes it easier for the spring claw 7 to disengage when it retracts inward. When the second inner protrusion 52 cooperates with the outer protrusion of the spring claw 7, the first inner protrusion 52 is located above the locking step 41, and the axial distance between the two is the locking distance that the adjuster can adjust.

[0027] The third inner boss 53 is located at the lower part of the inner wall of the outer jacket 5. The third inner boss 53 cooperates with the outer boss of the lower connector 9 to limit the axial movement of the outer jacket 5.

[0028] Since the central tube 4 is provided with sealing rings between the upper connector 1 and the outer sleeve 5 respectively, and the outer sleeve 5 is also provided with a sealing ring between the lower connector 9, a closed space is formed to ensure the initial fracturing pressure requirements. After the sliding sleeve 8 is removed, hydraulic boosting can be formed to separate the central tube 4 and the outer sleeve 5, forming a long clamping distance.

[0029] In field applications, firstly, an extension regulator of appropriate length is selected based on the reservoir thickness distribution and clamping distance adjustment requirements. This regulator, connected between the upper and lower packers, acts as the clamping tubing and is delivered to the target layer via the fracturing string for normal fracturing operations. When clamping distance adjustment is required for the next target layer, a ball is dropped at the wellhead. The ball lands on the sliding sleeve 8, sealing the central channel. Pressure is applied at the wellhead, shearing pin 11 is cut, and the sliding sleeve 8 moves downward after being released from its restraint. The spring claw 7, losing the support of the sliding sleeve 8, retracts inward, while the outer sleeve 5, freed from the constraint of the spring 7, slides downward. The outer sleeve 5 and the tubing below it slide down together until the first inner protrusion 51 on the outer sleeve 5 is engaged on the clamping step 41 of the central tubing 4, thus achieving clamping distance adjustment. The sliding distance of the outer sleeve 5 is the distance between the first inner protrusion 51 and the clamping step 41 of the central tubing 4. This distance can be designed in advance according to the reservoir thickness to achieve the effect of clamping distance adjustment and adapt to the requirements of fine-tuning of target layers with different thicknesses.

[0030] This regulator is connected between two packers during use, replacing part of the clamped tubing. When the regulator as a whole meets the initial clamping length, fracturing operations can be carried out smoothly. When the reservoir thickness increases and the packer spacing on the tubing string needs to be adjusted, the current conventional technology requires pulling the entire tubing string to the surface, increasing the tubing length between the two packers, and then re-running the entire tubing string to the predetermined position. However, this application uses an extendable regulator to replace part of the clamped tubing. Only a ball needs to be dropped at the wellhead, a predetermined pressure applied to shear the sliding sleeve pin, and the sliding sleeve is knocked off to release the elasticity of the spring claw. The center tube and the outer sleeve move relative to each other to the predetermined position under pressure. This allows for clamping adjustment without lifting the tubing string, thus adapting to fine-tuning of small layers with large thickness differences.

[0031] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or technical improvements to the embodiments in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A card length extender regulator for fracturing oil and gas wells, comprising an upper joint (1) having a central pipe (4) connected internally at the lower end, characterized in that: The outer sleeve (5) is slidably connected to the outside of the central tube (4), and the lower end of the central tube (4) is threadedly connected to the spring claw (7). The outer boss of the spring claw (7) cooperates with the inner boss on the inner wall of the outer sleeve (5). The spring claw (7) is provided with a sliding sleeve (8) inside, and the lower end of the spring claw (7) is provided with a lower connector (9). The sliding sleeve (8) and the lower connector (9) are connected by a shear pin (11).

2. The clamping distance extension adjuster for oil and gas well fracturing according to claim 1, characterized in that: The lower end of the central tube (4) is provided with a locking step (41), and the upper end of the outer sleeve (5) is provided with a first inner boss (51). The locking step (41) and the first inner boss (51) cooperate with each other.

3. The clamping distance extension adjuster for oil and gas well fracturing according to claim 2, characterized in that: The outer circumferential surface of the locking step (41) is in contact with the inner wall of the outer sleeve (5), and a sealing ring B (6) is provided at the contact point.

4. The clamping distance extension adjuster for oil and gas well fracturing according to claim 1, characterized in that: The inner wall of the outer jacket (5) is provided with a second inner boss (52) that cooperates with the outer boss of the spring claw (7). When the second inner boss (52) cooperates with the outer boss of the spring claw (7), the first inner boss (52) is located above the locking step (41).

5. The clamping distance extension adjuster for oil and gas well fracturing according to claim 4, characterized in that: The lower part of the inner wall of the outer jacket (5) is provided with a third inner boss (53), which cooperates with the outer boss of the lower connector (9).

6. The clamping distance extension adjuster for oil and gas well fracturing according to claim 5, characterized in that: The lower connector (9) is located inside the outer sleeve (5), and the lower connector (9) and the outer sleeve (5) are connected by threads and are provided with a lower anti-rotation pin (13).

7. The clamping distance extension adjuster for oil and gas well fracturing according to claim 5, characterized in that: The upper side wall of the first inner boss (51) on the outer jacket (5) has several axial cuts.

8. The clamping distance extension adjuster for oil and gas well fracturing according to claim 1, characterized in that: The upper end of the spring claw (7) is a cylinder, and the lower end of the cylinder is a number of circumferentially distributed individual spring claws with gaps between them.

9. The clamping distance extension adjuster for oil and gas well fracturing according to claim 1, characterized in that: The upper connector (1) is threadedly connected to the central tube (4) and is provided with an upper anti-rotation pin (3).

10. The clamping distance extension adjuster for oil and gas well fracturing according to any one of claims 1-9, characterized in that: During fracturing operations, when the next target layer requires adjustment of the clamping distance, a ball is dropped at the wellhead to apply pressure, shearing pin (11) is cut off, and sliding sleeve (8) moves down to release spring claw (7), thereby causing the outer sleeve (5) and the tubing below to slide down until the first inner boss (51) on the outer sleeve (5) is locked on the clamping step (41) of the central tube (4), thus realizing the clamping distance change.

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