Reverse well-flushing oil pipe plugging device for water well and use method of reverse well-flushing oil pipe plugging device

Abstract

The invention discloses a well backwashing oil pipe leaking stoppage device for a water well and a using method, the well backwashing oil pipe leaking stoppage device comprises an outer working barrel and further comprises a leaking stoppage core, the leaking stoppage core comprises a one-way valve and a locking claw which are sequentially connected from top to bottom, and the outer wall of the one-way valve is a stepped outer wall; the outer working barrel comprises a cylindrical shell, a central channel is arranged in the cylindrical shell, and the central channel is provided with a reducing step; the reducing step can be matched with the outer wall of the step, the locking claw can be clamped with the bottom of the cylindrical shell, and axial two-way positioning of the leaking stoppage core is achieved. The device adopts a split design, the outer working barrel goes down to a well along with the pipe column, the plugging core is put at any time according to the later pipe column leakage condition, and construction is convenient and simple.

Description

Technical Field

[0001] This invention relates to the field of oilfield water injection technology, specifically to a backwashable well tubing plugging device for water wells and its usage method. Background Technology

[0002] During the stratified water injection process in injection wells, corrosion, impurities, and scaling can cause perforation of the injection tubing or poor sealing of the well-washing valve ball seat, leading to tubing leakage. This, in turn, affects the water injection volume of each layer, resulting in failure to meet injection requirements. It can also cause packer leaks, ultimately leading to the failure of the entire injection tubing string. Currently available leak-sealing devices are mostly suitable for pressurized well operations and cannot backwash the well; they are temporary leak-sealing measures, such as:

[0003] Publication number CN115126454A discloses a tubing plug, including a delivery device, a sealing device, a locking device, and an unsealing device. The delivery device, connected by a steel wire, inserts the plug into the working cylinder at a reference position in the downhole tubing string. Upon reaching the reference position, the locking device locks the plug in place, preventing it from moving up and down. The sealing device utilizes the pressure of the downhole fluid to seal the gap between the working cylinder and the plug; the sealing performance increases with increasing formation pressure. The unsealing device allows the plug to be released from locking and sealing, enabling its retrieval and repeated deployment. This plug is primarily suitable for use during downhole pressurized operations requiring sealing of downhole fluid and pressure; it cannot meet the needs of tiered water injection tubing plugging for subsequent injection and backwashing.

[0004] Publication number CN113047804A discloses a drop-and-retrieve dual-acting plugger, comprising a pre-installed working cylinder and a plugger. In use, the pre-installed working cylinder 1 is connected to the wellbore string and lowered into the oil / gas well along with the wellbore string. The plugger is then dropped from the wellhead or lowered into the wellbore string using a wireline. By setting a bidirectional sealing assembly between the pre-installed working cylinder and the upper connector, bidirectional sealing of the tubing is achieved. This plugger is mainly suitable for downhole pressurized operations, achieving one-time sealing, but it cannot meet the needs of subsequent injection and backwashing wells after plugging leaks in stratified water injection tubing.

[0005] Publication number CN114439423A discloses a pump-type tubing plugging valve and its matching landing section. In use, it is directly deployed at the wellhead and, through free fall or pumping, is moved to the diameter-reducing position of the landing joint. The spring then opens, achieving bidirectional limiting of the tool. A self-sealing seal achieves bidirectional pressure separation within the tubing string. Later, a specialized retrieval tool is used to depress and retract the spring, and to lift the mandrel to shear the pin, thus restoring pressure between the upper and lower parts of the tubing plugging valve before retrieving it from the well. This plugging valve is suitable for temporarily sealing existing working tubing strings and opened reservoirs, where it cannot meet the needs of tiered water injection tubing for leak plugging and for well backwashing.

[0006] Publication No. CN216043627U discloses a well-washing tubing plugger employing a cup-and-ball seat structure. The cup comprises an internal metal skeleton and a rubber vulcanized layer vulcanized on the outside of the metal skeleton. Backwashing is achieved through internally connected ball seats. This patent relies on the cup for sealing and delivers pressure to the bottom of the well via a wellhead pump. It is only suitable for plugging leaks in the bottom-of-well flushing valve; it cannot plug leaks in other parts of the tubing string.

[0007] Publication number CN113982527A discloses a small-diameter tubing plugger, which belongs to the category of tubing plugging tools under pressure. Its main purpose is to plug tubing strings under pressure, and it is not suitable for the needs of sectional injection and backwashing wells after plugging leaks in stratified water injection tubing strings.

[0008] For leaks in the water injection tubing, it is necessary to meet the requirements of long-term water injection and backwashing wells while ensuring the leak is plugged. Currently, since there is no suitable treatment method, such wells can only be solved by moving the tubing and restarting the operation.

[0009] To address the shortcomings of current technology, this invention provides an in-tubing well-washing plugging device that can be directly deployed from the wellhead. The device moves within the tubing using gravity and is secured by a pre-installed outer working cylinder inside the tubing. This tubing plugging device can both seal leaking tubing and meet the requirements of backwashing, reducing workload, extending tubing life, and meeting the needs of efficient oilfield development. Summary of the Invention

[0010] In view of the above-mentioned defects in the existing technology, the purpose of this invention is to provide a backwashable well tubing plugging device and its usage method for water wells.

[0011] To achieve the above objectives, the present invention adopts the following technical solution:

[0012] On one hand, the present invention provides a backwashable tubing plugging device for water wells, including an outer working cylinder and a plugging core. The plugging core includes a one-way valve and a locking claw connected sequentially from top to bottom. The outer wall of the one-way valve is a stepped outer wall. The outer working cylinder includes a cylindrical shell with a central channel inside. The central channel has a reduced-diameter step. The reduced-diameter step can cooperate with the stepped outer wall, and the locking claw can engage with the bottom of the cylindrical shell to achieve axial bidirectional positioning of the plugging core.

[0013] Furthermore, the one-way valve includes an outer tube and an inner tube, the upper outer wall of the inner tube is threadedly connected to the lower inner wall of the outer tube, the lower end of the inner tube is connected to a locking claw, the inside of the inner tube is a backwash well channel, and the outer tube and the inner tube form a stepped outer wall;

[0014] Specifically, an inner convex ring is provided on the inner wall of the upper end of the outer tube, and a valve ball seat is provided at the upper end of the inner tube. A spring and a valve ball are arranged sequentially from top to bottom between the inner convex ring and the valve ball seat, and the spring presses the valve ball onto the valve ball seat.

[0015] Furthermore, an upper retaining ring is provided between the spring and the inner convex ring, and a lower retaining ring is provided between the spring and the valve ball;

[0016] Specifically, the lower baffle ring is slidably connected to the upper baffle ring via a central rod, and both the upper and lower baffle rings are hollow rings, allowing liquid to pass through them.

[0017] Furthermore, the valve ball is made of titanium carbide, the valve ball seat is made of tungsten carbide, and the upper and lower retaining rings are cross retaining rings.

[0018] Furthermore, a first sealing ring is provided on the outer wall of the inner tube to achieve sealing between the leak-stopping core and the outer working cylinder, and a second sealing ring is used to seal between the outer tube and the inner tube.

[0019] Furthermore, the locking claw includes at least three claw bars, the gap between the claw bars allows the claw bars to bend inward, and the claw bars are provided with teeth at the bottom;

[0020] Specifically, the claws adopt a trapezoidal structure, and a conical surface is provided on the outer side of the bottom of the claws to facilitate the contraction of the claws under pressure.

[0021] Furthermore, the corners within the reduced-diameter steps are smoothly transitioned using conical surfaces, and the central channel is provided with two levels of reduced-diameter steps, forming a large-diameter inner wall, a medium-diameter inner wall, and a small-diameter inner wall from top to bottom in the central channel;

[0022] Specifically, the large-diameter inner wall mates with the inner wall of the outer tube, the medium-diameter inner wall mates with the outer wall of the inner tube, and the small-diameter inner wall mates with the outer diameter circle formed by the grab rod;

[0023] Specifically, the bottom of the central channel is at a right angle, and the claws engage with the bottom of the central channel at a right angle.

[0024] Furthermore, an upper connector is provided at the upper end of the cylindrical shell, and a lower connector is provided at the lower end of the cylindrical shell.

[0025] Furthermore, the upper connector and the cylindrical shell are integrally formed, the lower connector and the cylindrical shell are connected by threads, and a third sealing ring is provided at the connection between the lower connector and the cylindrical shell.

[0026] Secondly, the present invention provides a method for using a water well reversible well tubing plugging device, wherein using the water well reversible well tubing plugging device described in one aspect includes the following steps:

[0027] S1. When the well is completed, depending on the actual well conditions and the quality of the injected water, install one or more stages of leak-stopping devices on the water injection tubing string, connect the outer working cylinder to the tool tubing string, and lower it into the well in advance.

[0028] S2. When leakage needs to be plugged, the plugging core is dropped from the wellhead into the tubing. Under the action of gravity, the plugging core moves downward into the outer working cylinder. The locking claws open after passing through the reduced diameter step. The claw teeth of the locking claws are fixed at the lower end of the central channel, thereby fixing the plugging core and completing the downhole sealing.

[0029] S3. When the injection well is injecting water normally, the water injection pressure from top to bottom enters the interior of the plugging core through the well washing channel of the plugging core. The one-way valve realizes the internal sealing of the plugging device, and the first sealing ring realizes the external pressure-bearing sealing function.

[0030] S4. During backwashing, the washing fluid flows upward from the bottom of the tubing, and the water injection pressure rises from bottom to top, entering the plugging core through the backwashing channel. The washing fluid then flows upward through the check valve into the upper tubing and is backwashed to the surface.

[0031] Compared with the prior art, the present invention has the following advantages:

[0032] 1. The device of this invention adopts a split design. The outer working cylinder is lowered into the well along with the tubing string, and the plugging core can be put in at any time according to the leakage of the tubing string in the later stage, which makes construction convenient and simple.

[0033] 2. The plugging core in the device of the present invention adopts a "locking claw + valve ball and valve seat" structure design to achieve a tight connection with the outer working cylinder, which is simple, convenient and not easy to break. At the same time, the valve ball and valve seat achieve "forward closure and reverse connection". During forward injection, the tubing is sealed to achieve the purpose of plugging leakage. During backwashing, it provides a backwashing channel.

[0034] 3. The device of this invention adopts a design of "anchoring mechanism + backwashing mechanism + sealing mechanism". The outer working cylinder is designed with a reduced diameter and stepped structure; the anchoring mechanism on the plugging core is designed with locking claws, which can be fixed on the steps inside the outer working cylinder; the device is designed with a valve ball and valve seat inside, and the plugging core is designed with a multi-ring sealing structure outside, which work together to achieve the functions of sealing the oil pipe and backwashing the well. Attached Figure Description

[0035] Fig. 1 This is a schematic diagram of the structure of a reverse-washing well tubing plugging device for water wells according to the present invention;

[0036] Fig. 2 This is a schematic diagram of the leak-sealing core in this invention;

[0037] Fig. 3 This is a schematic diagram of the structure of the outer working cylinder in this invention;

[0038] Fig. 4 This is a schematic diagram of the locking claw structure in this invention.

[0039] In the diagram: 1-Plugling core; 2-Outer working cylinder; 3-Upper retaining ring; 4-Outer pipe; 5-Spring; 6-Lower retaining ring; 7-Valve ball seat; 8-Valve ball; 9-First sealing ring; 10-Backwash well channel; 11-Second sealing ring; 12-Locking claw; 13-Upper connector; 14-Central channel; 15-Anti-loosening pin; 16-Third sealing ring; 17-Lower connector. Detailed Implementation

[0040] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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.

[0041] Example 1:

[0042] Please see Figs. 1 to 4 The present invention provides a backwashable well tubing plugging device for water wells, comprising a plugging core 1 and an outer working cylinder 2.

[0043] The plugging core 1 of the device includes an outer tube 4 and an inner tube. The upper outer wall of the inner tube is threadedly connected to the lower inner wall of the outer tube. The inside of the inner tube is a backwash well channel 10. An inner convex ring is provided on the upper inner wall of the outer tube 4. An upper retaining ring 3 is provided below the inner convex ring of the outer tube 4. A valve ball seat 7 is located at the upper end of the inner tube. A valve ball 8 is provided above the valve ball seat 7. A lower retaining ring 6 is provided above the valve ball 8. The lower retaining ring 6 is slidably connected to the upper retaining ring through a central rod. A spring 3 is provided between the upper retaining ring 3 and the lower retaining ring 6. The spring presses the valve ball 8 onto the valve ball seat 7. The upper retaining ring 3 and the lower retaining ring 6 are hollow rings, allowing liquid to pass through. A locking claw 12 is provided at the lower end of the inner tube, which can engage with the working cylinder 2.

[0044] The outer working cylinder 2 of the device includes a cylindrical shell, a central channel 14 is provided inside the cylindrical shell, the central channel 14 is provided with a reduced diameter step for fixing the plugging core 1, an upper connector 13 is provided at the upper end of the cylindrical shell, and a lower connector 17 is provided at the lower end of the cylindrical shell.

[0045] Among them, the valve ball 8 is made of titanium carbide and the valve ball seat 7 is made of tungsten carbide, which have good corrosion resistance and acid resistance.

[0046] Among them, the upper retaining ring 3 and the lower retaining ring 6 are hollowed out to form a cross retaining ring. The upper retaining ring 3 and the lower retaining ring 6 serve to fix the spring 3, and the central rod serves to orient it.

[0047] Among them, the spring 5 can press the valve ball 8 tightly onto the valve ball seat 7, ensuring that it is always in a sealed state during normal water injection, thus achieving the function of plugging leaks; at the same time, the design of the spring 5 mechanism provides the opening pressure for the backwash well. This design achieves constant pressure opening and closes when the well washing stops. Specifically, the opening pressure can be achieved by selecting different sizes of spring 5 according to the actual well conditions.

[0048] The inner tube has a first sealing ring 9 on its outer wall to seal the leak-stopping core 1 with the outer working cylinder 2.

[0049] The outer tube 4 and the inner tube are sealed with a second sealing ring 11, and a first anti-loosening nail is provided to strengthen the connection.

[0050] The inner tube and the locking claw 12 are connected by threads. The locking claw 12 includes at least three claw bars. The gap between the claw bars allows the claw bars to bend inward. The claw bars are provided with claw teeth at the bottom. The claw teeth adopt a trapezoidal structure design. The outer side of the bottom of the claw teeth is provided with a conical surface to facilitate the claw teeth to contract under pressure. The locking claw 12 opens after passing through the reduced diameter step of the central channel 14 of the outer working cylinder 2. The claw teeth are locked on the inner cavity of the outer working cylinder 2 to fix the leak-stopping core 1.

[0051] The upper connector 13 and the cylindrical shell are integrally formed, and the upper connector 13 is used for threaded connection with the oil pipe.

[0052] The lower connector 17 and the cylindrical housing are connected by threads. A third sealing ring 16 is provided at the connection between the lower connector 17 and the cylindrical housing. An anti-loosening nail 15 is also provided at the connection between the lower connector 17 and the cylindrical housing to strengthen the connection. The lower connector 17 is connected to the lower oil pipe.

[0053] The corners within the reduced-diameter steps are smoothly transitioned using tapered surfaces.

[0054] The central channel 14 is equipped with two-stage narrowing steps, forming a large-diameter inner wall, a medium-diameter inner wall, and a small-diameter inner wall from top to bottom. The large-diameter inner wall mates with the inner wall of the outer pipe 4, the medium-diameter inner wall mates with the outer wall of the inner pipe, and the small-diameter inner wall mates with the outer diameter circle formed by the grab rod. The bottom of the central channel 14 is at a right angle, and the claws engage with the right angle at the bottom of the central channel 14 to fix the plugging core 1. The narrowing steps prevent the plugging core 1 from moving downward, and the claws prevent the plugging core 1 from moving upward during backwashing.

[0055] Among them, at least two of the first sealing ring 9, the second sealing ring 11, and the third sealing ring 16 are provided to enhance the sealing effect.

[0056] Specifically, during well completion, the outer working cylinder 2 is connected to the water injection tool string on the tubing. The outer working cylinder 2 is positioned at the bottom of the tool string or elsewhere as needed, and is lowered into the well together. To meet routine measurement and adjustment requirements, the central channel 14 is sized to allow measurement and adjustment instruments to pass through smoothly.

[0057] Example 2:

[0058] Based on Example 1, this example provides a method for using a reverse-washing tubing plugging device for water wells, including the following steps:

[0059] S1. When the well is completed, connect the outer working cylinder 2 to the tool string and lower it into the well in advance. Depending on the actual well conditions and the quality of the injected water, a single-stage or multi-stage plugging device can be installed at a special position of the water injection string. The outer diameter of the plugging device increases from bottom to top.

[0060] S2. When leakage needs to be plugged, the plugging core 1 is dropped from the wellhead into the tubing. Under the action of gravity, the plugging core 1 moves downward into the outer working cylinder 2. The locking claw 12 opens after passing through the reduced diameter step. The claw teeth of the locking claw 12 are fixed at the lower end of the central channel 14 to fix the plugging core 1, thereby completing the downhole sealing.

[0061] S3. During normal water injection in the injection well, the water injection pressure from top to bottom enters the interior of the plugging core 1 through the well washing channel, pushing the valve ball 8 to press against the valve ball seat 7, thus achieving internal sealing of the plugging device; the first sealing ring 9 on the outer wall of the plugging core 1 cooperates with the outer working cylinder 2 to achieve external pressure sealing.

[0062] S4. When backwashing the well, the washing fluid flows upward from the bottom of the tubing, and the water injection pressure rises from bottom to top. It enters the plugging core 1 through the backwashing channel 10, overcomes the downward pressure of the spring 5 on the valve ball 8, pushes the valve ball 8 away from the valve ball seat 7, and the washing fluid flows upward into the upper tubing and back out to the surface, thus achieving backwashing.

[0063] All components not discussed in detail in this application, as well as the connection methods of these components, are well-known technologies in this field. They can be directly applied and will not be elaborated further.

[0064] In this invention, the term "multiple" refers to two or more unless otherwise explicitly defined. The terms "install," "connect," "link," and "fix" should be interpreted broadly. For example, "connect" can be a fixed connection, a detachable connection, or an integral connection; "link" can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0065] In the description of this invention, it should be understood that the terms "upper," "lower," "left," "right," "front," "rear," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or unit 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.

[0066] In the description of this specification, the terms "one embodiment," "some embodiments," "specific embodiment," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0067] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A backwashable well tubing plugging device for water wells, comprising an outer working cylinder, characterized in that, It also includes a leak-sealing core, which includes a one-way valve and a locking claw connected in sequence from top to bottom, and the outer wall of the one-way valve is a stepped outer wall; The outer working cylinder includes a cylindrical shell, and a central channel is provided inside the cylindrical shell. The central channel is provided with a diameter reduction step. The reduced-diameter step can mate with the outer wall of the step, and the locking claw can engage with the bottom of the cylindrical shell to achieve axial bidirectional positioning of the plugging core.

2. The water well reversible well tubing plugging device according to claim 1, characterized in that, The one-way valve includes an outer tube and an inner tube. The upper outer wall of the inner tube is threadedly connected to the lower inner wall of the outer tube. The lower end of the inner tube is connected to a locking claw. The inside of the inner tube is a backwash well channel. The outer tube and the inner tube form a stepped outer wall. The inner wall of the upper end of the outer tube is provided with an inner convex ring, and the upper end of the inner tube is a valve ball seat. A spring and a valve ball are arranged sequentially from top to bottom between the inner convex ring and the valve ball seat. The spring presses the valve ball onto the valve ball seat.

3. A water well tubing plugging device with reverse-washing capability according to claim 2, characterized in that, An upper retaining ring is provided between the spring and the inner convex ring, and a lower retaining ring is provided between the spring and the valve ball; The lower baffle ring is slidably connected to the upper baffle ring via a central rod. Both the upper and lower baffle rings are hollow rings, allowing liquid to pass through them.

4. A water well tubing plugging device with reverse-washing capability according to claim 3, characterized in that, The valve ball is made of titanium carbide, the valve ball seat is made of tungsten carbide, and the upper and lower retaining rings are cross retaining rings.

5. A water well tubing plugging device with reverse-washing capability according to claim 2, characterized in that, The outer wall of the inner tube is provided with a first sealing ring to achieve the sealing between the leak-stopping core and the outer working cylinder, and the outer tube and the inner tube are sealed with a second sealing ring.

6. A water well tubing plugging device with reverse-washing capability according to claim 2, characterized in that, The locking claw includes at least three claw bars, the gap between the claw bars allows the claw bars to bend inward, and the claw bars are provided with teeth at the bottom; The claws have a trapezoidal structure, and a conical surface is provided on the outer side of the bottom of the claws to facilitate the contraction of the claws under pressure.

7. A water well tubing plugging device with reverse-washing capability according to claim 6, characterized in that, The corners within the reduced-diameter steps are smoothly transitioned using conical surfaces. The central channel is provided with two levels of reduced-diameter steps, forming a large-diameter inner wall, a medium-diameter inner wall, and a small-diameter inner wall from top to bottom in the central channel. The large-diameter inner wall mates with the inner wall of the outer tube, the medium-diameter inner wall mates with the outer wall of the inner tube, and the small-diameter inner wall mates with the outer diameter circle formed by the grab rod; The bottom of the central channel is at a right angle, and the claws engage with the bottom of the central channel at a right angle.

8. A water well tubing plugging device with reverse-washing capability according to claim 1, characterized in that, The upper end of the cylindrical shell is provided with an upper connector, and the lower end of the cylindrical shell is provided with a lower connector.

9. A water well tubing plugging device with reverse-washing capability according to claim 9, characterized in that, The upper connector and the cylindrical shell are integrally formed, and the lower connector and the cylindrical shell are connected by threads. A third sealing ring is provided at the connection between the lower connector and the cylindrical shell.

10. A method of using a backwashable well tubing plugging device for water wells, characterized in that, The method of using the backwashable tubing plugging device for water wells according to claim 5 includes the following steps: S1. When the well is completed, depending on the actual well conditions and the quality of the injected water, install one or more stages of leak-stopping devices on the water injection tubing string, connect the outer working cylinder to the tool tubing string, and lower it into the well in advance. S2. When leakage needs to be plugged, the plugging core is dropped from the wellhead into the tubing. Under the action of gravity, the plugging core moves downward into the outer working cylinder. The locking claws open after passing through the reduced diameter step. The claw teeth of the locking claws are fixed at the lower end of the central channel, thereby fixing the plugging core and completing the downhole sealing. S3. When the injection well is injecting water normally, the water injection pressure from top to bottom enters the interior of the plugging core through the well washing channel of the plugging core. The one-way valve realizes the internal sealing of the plugging device, and the first sealing ring realizes the external pressure-bearing sealing function. S4. During backwashing, the washing fluid flows upward from the bottom of the tubing, and the water injection pressure rises from bottom to top, entering the plugging core through the backwashing channel. The washing fluid then flows upward through the check valve into the upper tubing and is backwashed to the surface.

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