Retractable hydraulic pump bottom valve

Abstract

The utility model relates to oilfield exploitation equipment technical field especially, relates to a hydraulic pump downhole tool, concretely is a kind of retractable hydraulic pump bottom valve, to solve the technical problem that hydraulic pump bottom valve fishing meets the card and easily leads to fishing tool string to fall well and causes oil well to lie well in prior art.The bottom valve includes capture head and bottom valve body, and its key lies in, the capture head is detachably connected on the bottom valve body by at least one shear pin with shear part.When bottom valve fishing meets the card and the applied tension exceeds preset shear force, the shear part of shear pin breaks, so that capture head and bottom valve body separate.

Description

Technical Field

[0001] This utility model relates to the field of oilfield extraction equipment technology, and in particular to a hydraulic pump downhole tool, specifically a retractable hydraulic pump bottom valve. Background Technology

[0002] The rodless hydraulic pump lifting technology has been widely used in heavy oil CO2 huff and puff enhancement development due to its strong adaptability to complex well conditions such as heavy oil, sand production, and high gas-liquid ratios. In the downhole tool string of a hydraulic pump well, the hydraulic pump foot valve is a key component. It is seated within a valve seat, forming a unidirectional flow channel. During normal production, it allows formation fluid to flow upwards; while during operations such as backwashing the pump core, it effectively prevents the power fluid from flowing downwards into the wellbore and contaminating the formation, and improves backwashing efficiency.

[0003] Before performing operations such as carbon dioxide injection and huffing / puffing that require injecting fluids downhole, the bottom valve inside the wellbore must first be retrieved to create a downward injection channel. Currently, the industry commonly uses a wireline retrieval method: a retrieval tool string is lowered via a wireline, aligned with the capture head on the top of the bottom valve, and then the wireline is pulled up to retrieve the entire bottom valve out of the well. This method is widely used due to its simplicity, speed, and low cost.

[0004] However, in actual operations, the bottom valves of some oil wells may become stuck due to complex conditions such as downhole scaling and sand production. When the bottom valve becomes stuck, it is often difficult to release it by relying solely on the pulling force of the wireline and the impact force generated by the retrieval tool. In this situation, if a large pulling force is continuously applied (usually less than the breaking strength of the wireline itself), the weak link at the connection between the wireline and the retrieval tool (such as the rope cap) is likely to fail or detach first, causing the entire retrieval tool set to fall into the well.

[0005] The retrieval tools that have been dropped into the well will accumulate above the stuck bottom valve, blocking the pump core passage inside the hydraulic pump's working barrel. This prevents the hydraulic pump core from being lowered back into the working barrel for operation, causing the oil well to be unable to produce normally or to carry out subsequent carbon dioxide injection, resulting in a serious "well lying down" accident that directly affects the oil well's production.

[0006] In existing technologies, the only way to resolve well-end accidents caused by stuck bottom valves during retrieval is through well workover operations. However, well workover operations require the writing and approval of cumbersome design and construction plans, coordination of workover teams, and are time-consuming and costly, leading to prolonged well shutdowns and significant economic losses. Analysis reveals that existing hydraulic pump bottom valves have the following inherent defects: the capture head and the valve body are typically an integral structure or a high-strength threaded connection, making active separation difficult in the downhole environment. For example, the bottom valve disclosed in Chinese Patent CN 119507853 A has a capture head that is difficult to separate from the body. Furthermore, commonly used mechanical slip-type retrieval tools (such as those disclosed in Chinese Patent CN 112922555 A) are almost impossible to detach downhole once successfully engaged with the capture head. This "firmly connected" design concept becomes the root cause of retrieval tools falling into the well when the bottom valve gets stuck.

[0007] Therefore, the existing technology has at least the following problems: (1) The structural design of the bottom valve of the hydraulic pump lacks an "insurance" mechanism to deal with the jamming during retrieval. Once jammed, it is very easy to cause the retrieval tools to fall into the well, resulting in a well-dwelling accident and affecting the oil well production. (2) The handling methods after the accident are limited, and can only rely on high-cost and long-cycle well repair operations, which cannot meet the needs of efficient oilfield production. Utility Model Content

[0008] To address the aforementioned problems in the prior art, namely the technical issue that when the bottom valve of a hydraulic pump gets stuck during retrieval, the retrieval tool string easily falls into the well, causing the oil well to become stranded, this utility model provides a retractable bottom valve for a hydraulic pump, comprising:

[0009] Capture head;

[0010] The bottom valve body includes an interception basket and a bottom valve body fixedly connected to the interception basket.

[0011] The capture head is detachably connected to the intercept basket via at least one shear pin;

[0012] The intercepting basket is provided with mounting holes for installing the shear pins, and the capturing head is provided with a limiting groove for the shear pins to engage.

[0013] The shear pin has a shear portion with a reduced diameter, which is used to shear and break when the tensile force on the capture head is greater than a preset shear force, thereby separating the capture head from the interception basket.

[0014] Furthermore, the top of the capture head is provided with tapered barbs for docking with the retrieval tool.

[0015] Furthermore, the mounting hole is a shear pin threaded hole, and the shear pin is installed in the shear pin threaded hole through a threaded connection.

[0016] Furthermore, after the shear pin is installed in the threaded hole of the shear pin, its outer end face is flush with or lower than the outer surface of the interception basket.

[0017] Furthermore, the number of the at least one shear pin is multiple, and the multiple shear pins are distributed circumferentially along the intercept basket.

[0018] Furthermore, the shearing pin includes a pin body, and the shearing portion is a shearing rod extending from the pin body and having a diameter smaller than that of the pin body.

[0019] Furthermore, the capture head is installed on the upper part of the interception basket, and the bottom valve body is installed on the lower part of the interception basket.

[0020] Furthermore, the interception basket is provided with an internal convex through hole and a flow channel for fluid to pass through.

[0021] Furthermore, it also includes a spherical valve disposed within the bottom valve body, the spherical valve being used to control the unidirectional flow of fluid through the bottom valve body.

[0022] Furthermore, the spherical valve is disposed within the body of the bottom valve and is opposite to the internal convex through hole. When the fluid flows upward, the spherical valve is pushed open, allowing the fluid to pass through the internal convex through hole and the flow channel.

[0023] The beneficial effects of this utility model are:

[0024] When the well gets stuck during retrieval, the capture head and retrieval tool string can be removed together by cutting the shear pin, which prevents the entire retrieval tool string from falling down and piling up in the working barrel due to being unable to get out of the jam, thus fundamentally eliminating the oil well lying down accident caused by this.

[0025] Since the retrieval tool string will not fall into the well, the bottom valve body and its single-flow function remain intact in the valve seat, and the hydraulic pump core can be normally lowered into the working barrel for production, thus avoiding long-term production stoppages caused by waiting for well repair operations and ensuring continuous production of the oil well.

[0026] When conventional wireline retrieval and unsticking measures (such as shock) fail, a reliable backup unsticking solution based on structural design is provided, which enriches the technical means to deal with retrieval failures on site and reduces the reliance on immediately initiating complex well workover operations in such situations. Attached Figure Description

[0027] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0028] Figure 1 This is a cross-sectional view of a retractable hydraulic pump foot valve according to this utility model;

[0029] Figure 2 This is a cross-sectional view of the capture head in a retractable hydraulic pump foot valve according to this utility model;

[0030] Figure 3 This is a cross-sectional view of the intercepting basket in a retractable hydraulic pump foot valve according to this utility model;

[0031] Figure 4 This is a diagram of a shear pin in a retractable hydraulic pump foot valve according to this utility model. Detailed Implementation

[0032] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings.

[0033] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0034] This embodiment proposes a retractable hydraulic pump foot valve, including a capture head 1 and a foot valve body. The foot valve body includes an interception basket 2 and a foot valve body 4 fixedly connected to the interception basket 2. The capture head 1 is detachably connected to the interception basket 2 by at least one shear pin 2-4. The interception basket 2 is provided with a mounting hole for installing the shear pin 2-4. The capture head 1 is provided with a limiting groove 1-2 for the shear pin 2-4 to engage. The shear pin 2-4 has a shearing part 2-5 with a reduced diameter. The shearing part 2-5 is used to shear and break when the tensile force on the capture head 1 is greater than a preset shearing force, thereby separating the capture head 1 from the interception basket 2.

[0035] like Figure 1As shown, the capture head 1 is positioned at the upper port of the interception basket 2, and the bottom valve body 4 is fixedly connected to the lower part of the interception basket 2 via threads, together forming the bottom valve body. The columnar lower part of the capture head 1 extends into the upper hole of the interception basket 2, and its outer wall is provided with a ring-shaped limiting groove 1-2. A radial mounting hole is machined on the side wall of the interception basket 2, and this mounting hole is a threaded hole. The shear pin 2-4 is screwed into this mounting hole from the outside of the interception basket 2, and its end is embedded in the limiting groove 1-2 of the capture head 1, thereby realizing the separable connection between the capture head 1 and the interception basket 2. The shear pin 2-4 is not a single piece of uniform diameter; it has a shearing part 2-5 with a diameter significantly smaller than that of the main body of the pin, such as... Figure 4 As shown, the shearing section 2-5 serves as a stress concentration point. When the retrieval encounters a jam and the pulling force applied to the capture head 1 exceeds a preset value, the shearing section 2-5 will break, and the capture head 1 will detach from the interception basket 2. During field implementation, the number of pins to be installed and the diameter of the shearing rod are predetermined based on the specific well conditions and retrieval tools to set the required preset shearing force. The advantage of this is that when retrieval encounters a jam, a preset, reliable mechanical separation point is provided, which can force the capture head to detach from the retrieval tool string and remove it, preventing the entire retrieval tool string from falling into the well and getting stuck inside the working barrel. This fundamentally prevents well collapse accidents caused by failed retrieval, ensuring production continuity or buying time for subsequent measures.

[0036] As a further explanation of this utility model, the top of the capture head 1 is provided with a conical barb 1-1 for docking with the retrieval tool.

[0037] like Figure 2 As shown, the top of the capture head 1 is machined with conical barbs 1-1. The outer surface of the conical barbs 1-1 is conical, with several downward-facing serrations or stepped structures distributed on it. When a retrieval tool, such as a slip retrieval cylinder, is lowered onto the capture head 1, the conical surface facilitates guidance and centering. The internal slips and other gripping mechanisms can descend and expand along the conical surface, and after passing the barbs, the slips retract, their teeth locking under the barbs for reliable gripping. The advantage of this design is that the conical structure facilitates guidance and gripping, while the barb design effectively prevents accidental detachment during the lifting process after gripping, ensuring the initial success rate and reliability of the retrieval operation.

[0038] As a further explanation of this utility model, the mounting hole is a shear pin threaded hole 2-1, and the shear pin 2-4 is installed in the shear pin threaded hole 2-1 by a threaded connection.

[0039] like Figure 3As shown, the hole on the side wall of the interceptor basket 2 for installing the shear pin 2-4 is machined with internal threads, namely the shear pin threaded hole 2-1. Correspondingly, the pin body of the shear pin 2-4 is machined with external threads. During assembly, a tool such as a screwdriver is used to screw the shear pin 2-4 into the shear pin threaded hole 2-1 until the shearing rod at its end enters the limiting groove 1-2 of the capture head 1. During installation, it is necessary to ensure that the shear pin 2-4 is completely recessed into the shear pin threaded hole 2-1. The advantage of this is that the threaded connection is firm and reliable, ensuring that the shear pin will not loosen under normal production vibration; at the same time, this connection method also facilitates the selection and replacement of different specifications of shear pins when adjusting the preset shearing force according to the well conditions on site, improving the adaptability and flexibility of the tool.

[0040] As a further explanation of this utility model, after the shear pin 2-4 is installed in the shear pin threaded hole 2-1, its outer end face is flush with or lower than the outer surface of the interception basket 2.

[0041] After the shear pin 2-4 is fully screwed into the shear pin threaded hole 2-1 of the intercepting ball basket 2, the threaded main body of the shear pin 2-4 is completely sunk into the threaded hole, with its outermost end face flush with or slightly lower than the outer wall surface of the intercepting ball basket 2, forming a concave or flat surface. This design prevents the head of the shear pin 2-4 from protruding from the outer wall of the intercepting ball basket 2, significantly reducing the risk of the pin head scraping or getting stuck on downhole tools or casing walls during the lowering, retrieval, or production of the bottom valve, thus improving tool accessibility and the safety of downhole operations.

[0042] As a further explanation of this utility model, there are at least a plurality of shear pins 2-4, and the plurality of shear pins 2-4 are distributed along the circumference of the interception basket 2.

[0043] On the upper part of the intercept basket 2, multiple shear pin threaded holes 2-1 are evenly spaced around its axis. Correspondingly, an equal number of shear pins 2-4 are screwed into these threaded holes, with the shearing rod of each shear pin 2-4 embedded in the corresponding annular limiting groove 1-2 on the capture head 1. The advantage of this is that the evenly distributed circumferential distribution of multiple pins allows for more uniform force distribution on the capture head 1, resulting in a more stable connection and preventing uneven loading caused by single-point force. Simultaneously, by adjusting the number of pins, the overall connection strength and preset shear force can be adjusted within a certain range to adapt to different well depths and expected jamming conditions.

[0044] As a further explanation of this utility model, the shearing pin 2-4 includes a pin body and the shearing part 2-5 is a shearing rod extending from the pin body and having a diameter smaller than that of the pin body.

[0045] like Figure 4As shown, the shearing pin 2-4 mainly consists of two parts: a cylindrical pin body with external threads and a thin rod extending coaxially from one end of the pin body, namely the shearing rod 2-5. The diameter of the shearing rod 2-5 is much smaller than the diameter of the pin body, and a step is formed at the connection between the two, creating a significant stress concentration area. After assembly, the pin body is located in the threaded hole 2-1 of the shearing pin, while the shearing rod 2-5 passes laterally through and is locked in the limiting groove 1-2 of the capture head 1. When the retractable hydraulic pump bottom valve is unsuccessfully retrieved, the steel wire is repeatedly raised and lowered, causing the retrieval tool string to repeatedly vibrate. The capture head 1 also moves repeatedly under the action of the retrieval tool string. Under the repeated upward shearing force of the pin limiting groove 1-2, the shearing rod 2-5 gradually deforms and displaces, eventually being sheared off. The advantage of this design is that the stepped shaft structure cleverly creates a precise weak point. By precisely controlling the diameter and material of the shearing rod, its shearing force can be accurately controlled, ensuring reliable breakage when the predetermined shearing force is reached, thus separating the capture head. Meanwhile, the main body of the pin remains firmly inside the interception basket, resulting in a clear structure and controllable performance.

[0046] As a further explanation of this utility model, the capture head 1 is installed on the upper part of the interception basket 2, and the bottom valve body 4 is installed on the lower part of the interception basket 2.

[0047] like Figure 1 As shown in the overall sectional view, the entire retractable hydraulic pump foot valve adopts a three-section layout in the vertical direction. The capture head 1 is located at the top, and its function is to dock with the retrieval tool. The interception basket 2 is located in the middle, with an internal flow channel, and is the core component for realizing the retractable function. The foot valve body 4 is located at the bottom, and houses the spherical valve 3 for setting in the fixed valve seat downhole. The capture head 1 docks with the upper port of the interception basket 2 and is connected by shear pins 2-4, while the foot valve body 4 is fixed to the lower port of the interception basket 2 by threads. When assembling the retractable hydraulic pump foot valve, place the capture head 1 into the upper part of the interception basket 2, aligning the shear pin threaded hole 2-1 with the pin limiting groove 1-2; install the shear pin 2-4; place the spherical valve 3 into the foot valve body 4, and fix the interception basket 2 to the foot valve body 4. The advantage of this design is that the structure is clearly hierarchical and the functional areas are clearly defined: the upper part is responsible for salvage connection and emergency separation, the middle part is responsible for the flow and load separation mechanism, and the lower part is responsible for the one-way valve function. Each part has its own function, and maintenance and assembly are also more convenient.

[0048] As a further explanation of this utility model, the interception basket 2 is provided with an internal convex through hole 2-2 and a flow channel 2-3 for fluid to pass through.

[0049] like Figure 3As shown, the interception basket 2 has a complex flow channel structure inside. At its center is a vertically penetrating convex stepped hole, namely the internal convex through-hole 2-2. The upper part of this through-hole has a larger diameter, while the lower part has a smaller diameter, forming a stepped surface. Around the internal convex through-hole 2-2, i.e., in the side wall area of ​​the interception basket 2, several vertical flow channels 2-3 are formed, penetrating the basket body. These channels can be round holes or elongated holes. During normal production, the formation produced fluid, under the suction action of the upper hydraulic pump, pushes open the spherical valve 3 inside the retractable hydraulic pump foot valve, and then enters the hydraulic pump suction port through the internal convex through-hole 2-2 and the flow channels 2-3. The advantage of this design is that the internal convex through-hole 2-2 can guide and limit the up and down movement of the spherical valve 3, and its stepped surface can also serve as a sealing seat for the valve ball; while the surrounding flow passage 2-3 provides additional fluid passages, together forming a main flow path with a large flow area and low flow resistance, ensuring that the formation produced fluid can enter the hydraulic pump suction port efficiently.

[0050] As a further explanation of this utility model, it also includes a spherical valve 3 disposed in the bottom valve body 4, the spherical valve 3 being used to control the unidirectional flow of fluid through the bottom valve body.

[0051] like Figure 1 As shown, a spherical valve 3, or valve ball, is placed inside the cavity of the bottom valve body 4. The lower end of the bottom valve body 4 is usually designed with a reduced-bore valve port or fitted with a valve seat. During normal production, the formation fluid flows from bottom to top, impacting the spherical valve 3 and lifting it up. The fluid then flows through the annular gap between the ball and the valve seat, as well as the flow passage of the ball basket. When the fluid stops flowing or backflow occurs, the spherical valve 3 falls back under its own weight and pressure differential, settling on the bottom valve seat to form a seal. The advantage of this is that, utilizing the simple structure and reliable sealing characteristics of the spherical valve, a strict one-way valve function is achieved, effectively preventing the power fluid from entering the formation and causing contamination during backwashing, while ensuring the smooth lifting of the formation fluid during normal production.

[0052] As a further explanation of this utility model, the spherical valve 3 cooperates with the internal convex through hole 2-2 to realize the one-way valve opening and closing function.

[0053] like Figure 1 and Figure 3As shown, the diameter of the spherical valve 3 is larger than the small diameter of the lower section of the convex through-hole 2-2 inside the intercepting basket 2, but smaller than the large diameter of the upper section. When the fluid flows upward and pushes up the spherical valve 3, the sphere rises and can enter the upper large-diameter area of ​​the convex through-hole 2-2. The fluid then passes smoothly through the sphere, the convex through-hole 2-2, and the surrounding flow channels 2-3. When sealing is required, the spherical valve 3 falls, and its spherical surface contacts the annular sealing line formed by the edge of the small hole at the lower end of the convex through-hole 2-2, achieving sealing and cutoff. When the retractable hydraulic pump foot valve cannot be retrieved, the capture head 1 has been removed, but the retractable hydraulic pump foot valve remains inside the valve seat, and the spherical valve 3 can still be opened and closed normally within the convex through-hole 2-2, ensuring continued oil well production. The advantage of this design is that the large upper space of the internal convex through-hole 2-2 provides ample displacement space for the valve ball to open, avoiding throttling, while the edge of the lower small hole forms a precise sealing pair. This combination makes the opening and closing action of the check valve more sensitive and reliable, with a large flow capacity and good sealing effect. Even after a failed retrieval attempt and the capture head is removed, the core check valve function of the bottom valve body remains intact, ensuring the continuity of oil well production.

[0054] The terms “first”, “second”, etc., are used to distinguish similar objects, not to describe or indicate a specific order or sequence.

[0055] The term "comprising" or any other similar term is intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus / device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent in such process, method, article, or apparatus / device.

[0056] The technical solution of this utility model has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the protection scope of this utility model is obviously not limited to these specific embodiments. Without departing from the principle of this utility model, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the protection scope of this utility model.

Claims

1. A retractable foot valve for a hydraulic pump, characterized in that, include: Capture head (1); Bottom valve body, the bottom valve body includes an interception basket (2) and a bottom valve body (4) fixedly connected to the interception basket (2). The capture head (1) is detachably connected to the intercept basket (2) by at least one shear pin (2-4); The intercepting basket (2) is provided with mounting holes for installing the shear pins (2-4), and the capturing head (1) is provided with limiting grooves (1-2) for the shear pins (2-4) to engage. The shear pin (2-4) has a shear portion (2-5) with a reduced diameter. The shear portion (2-5) is used to shear and break when the tension on the capture head (1) is greater than the preset shear force, thereby separating the capture head (1) from the intercept basket (2).

2. The retractable hydraulic pump foot valve according to claim 1, characterized in that, The top of the capture head (1) is provided with a conical barb (1-1) for docking with the retrieval tool.

3. The retractable hydraulic pump foot valve according to claim 1, characterized in that, The mounting hole is a shear pin threaded hole (2-1), and the shear pin (2-4) is installed in the shear pin threaded hole (2-1) by threaded connection.

4. The retractable hydraulic pump foot valve according to claim 3, characterized in that, After the shear pin (2-4) is installed in the shear pin threaded hole (2-1), its outer end face is flush with or lower than the outer surface of the interception basket (2).

5. The retractable hydraulic pump foot valve according to claim 1, characterized in that, The number of the at least one shear pin (2-4) is multiple, and the multiple shear pins (2-4) are distributed circumferentially along the intercept basket (2).

6. The retractable hydraulic pump foot valve according to claim 1, characterized in that, The shearing pin (2-4) includes a pin body and the shearing part (2-5) is a shearing rod extending from the pin body and having a diameter smaller than that of the pin body.

7. The retractable hydraulic pump foot valve according to claim 1, characterized in that, The capture head (1) is installed on the upper part of the interception basket (2), and the bottom valve body (4) is installed on the lower part of the interception basket (2).

8. The retractable hydraulic pump foot valve according to claim 1, characterized in that, The interception basket (2) is provided with an internal convex through hole (2-2) and a flow channel (2-3) for fluid to pass through.

9. The retractable hydraulic pump foot valve according to claim 8, characterized in that, It also includes a ball valve (3) disposed in the bottom valve body (4), the ball valve (3) being used to control the fluid to pass through the bottom valve body in one direction.

10. The retractable hydraulic pump foot valve according to claim 9, characterized in that, The spherical valve (3) is disposed inside the bottom valve body (4) and is opposite to the internal convex through hole (2-2). When the fluid flows upward, the spherical valve (3) is pushed open, allowing the fluid to pass through the internal convex through hole (2-2) and the flow channel (2-3).

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