A pumping wellhead flow process anti-backflow device and method

Abstract

The present disclosure relates to a pumping unit wellhead flow process anti-backflow device and method, the anti-backflow device comprising a check valve arranged between an oil pipe and an oil return pipeline, an inlet of the check valve being connected to a cyclone generating mechanism (8), the cyclone generating mechanism (8) comprising a housing connected to the inlet, a central shaft and at least one cyclone vane being integrally fixed in the housing, the central shaft being olive or olive-shaped, a cyclone channel for crude oil being formed between adjacent two cyclone vanes; a cyclone generating mechanism is arranged below the check valve, a strong and high-flow-rate cyclone generated by the cyclone generating mechanism is used to flush, carry and flow into the oil return pipeline the sundries affecting the sealing of the check valve seat, a self-cleaning effect is generated, and the purpose of anti-backflow of the pumping unit wellhead flow process is achieved.

Description

Technical Field

[0001] This disclosure relates to the field of pumping unit wellhead process technology, specifically to a pumping unit wellhead process anti-backflow device and anti-backflow method. Background Technology

[0002] The statements in this section provide only background information in connection with this disclosure and do not constitute prior art.

[0003] The wellhead process of the pumping unit uses a check valve to control the flow of crude oil extracted by the pumping unit from the tubing into the return line, and to prevent crude oil in the return line from flowing back into the tubing. When the pumping unit is in its upstroke, the crude oil moves upward with the pumping unit and accumulates pressure at the check valve. Once the check valve reaches its opening pressure, it opens, and the crude oil flows into the return line. When the pumping unit is in its downstroke, the pumping pump replenishes crude oil into the tubing, the check valve closes, and crude oil in the return line does not flow back into the tubing.

[0004] In field wellhead processes, check valves are generally available in two types: ball-seated and plunger-type. Compared to ball valves, plunger valves offer better centering and faster closure, but their setting effect is not as tight. Because the crude oil in the tubing often contains debris such as packing debris, formation sand, wax blocks, and scale, both ball-seated and plunger-type check valves used in the field are easily clogged by these impurities, especially packing debris and wax blocks, causing a connection between the tubing and the return line. In this situation, during the pumping unit's upstroke, the crude oil in the tubing rises to the check valve without being pressurized and directly enters the return line, leaving the check valve in a clogged state and unable to open significantly. During the pumping unit's downstroke, crude oil from the return line flows back into the tubing, and the check valve remains clogged, unable to return to its original position, thus losing its flow control function.

[0005] For the problem of flow valve failure caused by impurities in the fluid, existing technologies mainly address it through filtration and flushing. For example, the "Wellhead Flow Valve" disclosed in patent number "ZL 201821465620.2" employs a filter device designed below the valve core assembly (i.e., the structure indicated by symbol 9 in the flow valve structure diagram) to prevent the deposition of welding slag, mechanical impurities, scale, etc., on the ball seat, leading to sealing failure. However, the application of the filter device has three main problems: First, the filter screen is easily clogged by impurities, preventing crude oil from passing through the flow valve, causing continuous pressure buildup, resulting in packing leakage and crude oil spillage at the well site; second, the filter screen requires regular cleaning, increasing maintenance workload, and the disassembly and shutdown of the well affects crude oil production; third, the filter screen requires space, which limits improvements in existing processes, and the near-planar surface of the filter screen makes it prone to clogging. For example, the patent "ZL 202210907628.4" discloses a "self-cleaning check valve," which uses a vortex generator (the structure indicated by structural symbol 12 in the patent) designed below the pump seat to change the flow state of the liquid before it enters the valve seat, thus achieving a self-cleaning effect and extending the service life of the pump. However, when this structure is used on a pump, during the pumping unit's upstroke, the pump plunger moves upward to draw crude oil, and the fixed valve ball can still open. The vortex generator changes the fluidity of the crude oil, increasing the flushing effect and cleaning away impurities, allowing the valve seat to re-seat. However, if the check valve used in the wellhead process is blocked by impurities, the tubing and return line are connected, and the crude oil moving upward during the pumping unit's upstroke directly enters the return line. The check valve is in a failed state and will not re-seat, making it unusable directly. Furthermore, the vortex generator is a threaded cone-shaped structure fixed by a support rib (i.e., the structure indicated by the patent structural symbol 13). When crude oil passes through the vortex generator, it is rotated to a certain extent by the threads on it, but the degree of vortex generation is small and the flushing effect is not strong. When the vortex generator blocks the crude oil, the crude oil pressure is high, the support rib is under great stress and is prone to breakage, the vortex generator falls off, and loses the vortex generation function designed to generate vortex.

[0006] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art. Summary of the Invention

[0007] In view of this, this disclosure provides a device and method for preventing backflow in the wellhead process of an oil pumping unit, which solves the problem that the single-flow valve used in the wellhead process of an oil pumping unit is prone to losing its single-flow control function due to impurities mixed in the fluid.

[0008] To achieve the aforementioned objective, in a first aspect, the anti-backflow device for the pumping unit wellhead process includes a check valve disposed between the tubing and the return pipeline, wherein:

[0009] The inlet of the single-flow valve is connected to a swirling mechanism, which includes a housing connected to the inlet. The housing contains an integrally fixed central shaft and at least one swirling vane. The central shaft is olive-shaped or olive-like, and a swirling channel for crude oil is formed between two adjacent swirling vanes.

[0010] In this disclosure and possible embodiments, the swirl vanes are helical blades, and the number of vanes is 3 to 5.

[0011] In this disclosure and possible embodiments, the helical blade is a helical hyperboloid blade, and the number of blades is 3.

[0012] In this disclosure and possible embodiments, the helical blade is a hyperboloidal helical blade with an angle of inclination of 30° to 41° with respect to the axis.

[0013] In this disclosure and possible embodiments, the lower part of the housing of the swirl generating mechanism is nested within the rising channel of the oil pipe.

[0014] In this disclosure and possible embodiments, the one-way valve includes a valve body, a plunger-type valve core, and a return spring, wherein the inlet and outlet of the valve body are respectively connected to the oil pipe and the return oil line;

[0015] The plunger-type valve core includes a plunger head and a plunger rod, the plunger rod is provided with a central groove, and a return spring is fitted through the central groove;

[0016] During the upstroke of the pumping unit, the hydraulic pressure of the oil pipe and the return force of the return spring during the downstroke of the pumping unit drive the plunger head to move up or down relative to the valve body to open or close the return oil line.

[0017] In this disclosure and possible embodiments, a spindle-shaped groove is provided at the lower part of the plunger head, and a spindle-shaped seal is fitted inside the spindle-shaped groove.

[0018] In this disclosure and possible embodiments, the spindle-shaped seal is a spindle-shaped rubber ring.

[0019] In this disclosure and possible embodiments, the bottom of the plunger head is a conical structure;

[0020] The cone-shaped structure forms a surface seal or line seal with the upper port of the housing of the vortex generating mechanism.

[0021] In this disclosure and possible embodiments, the valve body includes a valve cover, and a valve cap is connected to the top of the valve cover;

[0022] A window is opened on the side of the valve cover to serve as the outlet of the valve body;

[0023] The valve cap has a travel guide for the plunger rod, and the side of the central groove of the plunger rod has a through hole. During the upstroke or downstroke of the pumping unit, the through hole communicates with the valve cavity of the valve body.

[0024] In this disclosure and possible embodiments, sealing rings are respectively provided on the upper part of the valve cover and the bottom end face of the valve cover.

[0025] Secondly, a method for preventing backflow at the wellhead of an oil pumping unit includes:

[0026] The lower part of the housing of the vortex generator of the anti-backflow device for the pumping unit wellhead process described in any of the first aspects is nested in the rising channel of the tubing, and the outlet of the single-flow valve is connected to the outlet pipeline of the pumping unit wellhead.

[0027] In this disclosure and possible embodiments, the one-way valve includes a plunger-type valve core and a return spring. During the upstroke of the pumping unit, crude oil mixed with impurities flows from the oil pipe through the swirling mechanism and acts on the bottom of the plunger-type valve core, pushing the plunger-type valve core upward and compressing the return spring to open the one-way valve. The crude oil then flows into the return oil line. Simultaneously, the swirling channel accelerates the outflow velocity of the crude oil to flush away the impurities affecting the closing of the plunger-type valve core, which then flow into the return oil line along with the crude oil. When the pumping unit enters the downstroke, the crude oil pressure is less than the spring force of the return spring and the return oil pressure. The return spring rebounds, the plunger-type valve core moves downward to reset, and the one-way valve closes.

[0028] In this disclosure and possible embodiments, the plunger valve core includes a plunger head and a plunger rod. A shuttle-shaped seal is provided at the lower part of the plunger head. During the upstroke of the pumping unit, the shuttle-shaped seal scrapes the valve cavity wall of the one-way valve to prevent the plunger valve core from getting stuck. During the upstroke of the pumping unit, the plunger head is guided to move down to reset and set.

[0029] In this disclosure and possible embodiments, the plunger rod is provided with a central groove, through which the return spring is fitted, and a through hole is opened on the side of the central groove; the valve body of the one-way valve is provided with a piston rod stroke guide rail, and the central groove and the stroke guide rail form an independent chamber. When the plunger valve core moves upward, crude oil in the independent chamber flows out through the through hole.

[0030] In this disclosure and possible embodiments, the bottom of the plunger valve core is a conical structure, and the conical structure forms a surface seal or line seal with the upper port of the housing of the vortex generating mechanism. If there is debris between the conical structure and the upper port of the housing, and the surface seal or line seal fails, the plunger valve core uses the plunger head and the shuttle-shaped seal to perform a seat seal to prevent backflow.

[0031] The beneficial effects of this invention are as follows:

[0032] This disclosed anti-backflow device for pumping unit wellhead processes features a vortex generator below the flow valve. The high-intensity, high-velocity vortex generated by this mechanism flushes away and carries away debris affecting the flow valve seat seal when the bottom of the plunger valve core is blocked by debris. This debris is then channeled into the return oil line, achieving self-cleaning and preventing backflow. Furthermore, the vortex generator is nested within the lower tubing, rationally allocating space for each function. Because the debris is flushed away and carried into the return oil line, it does not remain on the plunger seat cover, eliminating the need for regular cleaning, reducing maintenance workload, and lowering the risk of wellhead packing leakage. In field applications, this anti-backflow device does not require adjustments to the wellhead process flow; only the flow valve needs to be replaced. The process modification is simple, inexpensive, and widely applicable. Attached Figure Description

[0033] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this disclosure and, together with the specification, serve to illustrate the technical solutions of this disclosure.

[0034] Figure 1 This is a front view of the anti-backflow device at the wellhead of the pumping unit according to an embodiment of the present invention;

[0035] Figure 2 This is a front view of a three-dimensional model of the anti-backflow device for the pumping unit wellhead process according to an embodiment of the present invention;

[0036] Figure 3 This is a perspective view of a three-dimensional model of the anti-backflow device at the wellhead of the pumping unit according to an embodiment of the present invention.

[0037] Figure 4 shows the right view, front view, and left view of the vortex generating mechanism according to an embodiment of the present invention;

[0038] Figure 5 This is a perspective view of the vortex generating mechanism according to an embodiment of the present invention;

[0039] Figure 6 This is a schematic diagram of the structure of the helical hyperboloid blade according to an embodiment of the present invention;

[0040] Figure 7 The results of computer fluid analysis are shown for the helical hyperboloid blade tilt angle of 30-41° in this embodiment of the invention.

[0041] In the diagram: 1. Valve cap; 2. Upper sealing ring; 3. Piston valve core; 4. Return spring; 5. Valve cover; 6. Shuttle-shaped rubber ring; 7. Lower sealing ring; 8. Swirl generator mechanism; B. Through hole; C. Valve cover window. Detailed Implementation

[0042] The present disclosure is described below based on embodiments; however, it is worth noting that the present disclosure is not limited to these embodiments. In the detailed description of the present disclosure below, certain specific details are described in detail. However, those skilled in the art will fully understand the present disclosure for the parts not described in detail.

[0043] Furthermore, unless the context explicitly requires it, the words "comprising," "including," and similar terms throughout the specification and claims should be interpreted as including rather than exclusive or exhaustive; that is, meaning "including but not limited to."

[0044] In the description of this invention, it should be noted that the terms "upper" and "lower" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of this invention is usually placed when in use. They are only used to facilitate the description of this invention and to simplify the description, and are not intended to indicate or imply that the device or element 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.

[0045] The following detailed description of some embodiments of the present invention is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0046] like Figure 1-3 As shown in the embodiment of this disclosure, the anti-backflow device for the pumping unit wellhead process includes: valve cap 1, upper sealing ring 2, plunger valve core 3, return spring 4, valve cover 5, shuttle-shaped rubber ring 6, lower sealing ring 7, vortex generating mechanism 8, through hole B, and valve cover window C.

[0047] In this embodiment, the valve cap 1 has three steps. The top step is machined into an octagonal nut for wrench positioning and rotation to complete the disassembly and assembly of the anti-backflow device. The middle step has threads for the anti-backflow device installation and positioning. The top of the thread in the middle step has a groove for the upper sealing ring 2 to be fitted. The bottom step has threads for threaded connection with the valve cover 2. The valve cap 1 has an opening from the bottom center upwards to the same height as the outer upper sealing ring 2 for assembling the plunger rod of the plunger valve core 3 and the return spring 4. The opening depth ensures that the rod of the first step of the plunger valve core 3 can enter smoothly, maintaining good alignment of the plunger valve core 3.

[0048] In this embodiment, the upper sealing ring 2 is nested with the valve cap 1 and is positioned at the top of the thread on the middle step of the valve cap 1. It is used for the overall sealing of the anti-backflow device to prevent crude oil from leaking out from the thread gap of the valve cap 1.

[0049] In this embodiment, the plunger valve core 3 is divided into two steps: a thinner upper section and a coarser lower section. The thinner upper section forms the plunger rod, with a central groove in the middle for mounting the return spring 4. Near the lower region, there is an opening B for the inlet and outlet of crude oil during compression and rebound of the return spring 4. The coarser lower section forms the plunger head. It is important to note that the plunger head is designed as a "long plunger" structure, with a conical bottom, which is a crucial component of the multi-seal design. The sealing surface of the plunger head consists of two areas: a sloped surface and a vertical surface. The sloped surface contacts the top of the vortex generator 8 to form a line seal or surface seal, serving as the first seal of the anti-backflow device. The vertical surface is longer and wider than that of a typical plunger-type flow valve, and its height, combined with the height below the window opening of the valve cover 5, achieves a multi-seal effect, ensuring that even the sloped bottom of the plunger head... Even after being padded with debris such as rubber blocks and wax blocks, part of the plunger head has already entered below the window opening of the valve cover 5, yet it can still maintain a sealing effect. It is also worth emphasizing that the vertical surface is provided with a shuttle-shaped groove for fitting the shuttle-shaped rubber ring 6, which serves as a reinforced seal for the anti-backflow device, further ensuring that the seal remains intact even when the inclined surface is padded with debris. It is also worth emphasizing the design of the shuttle-shaped rubber ring 6, which expands outward when the plunger valve core 3 moves upward, scraping out the sand in the gap and preventing the plunger valve core 3 from being stuck by sand. When the plunger valve core 3 moves downward, it closes inward, making it easier to enter the lower space of the valve cover 5, thus enhancing the sealing effect. At the same time, the plunger rod and the valve cap 1 have an upward opening from the bottom center, and the plunger head has a good centering with the inner hole of the valve cover 1 through the shuttle-shaped sealing ring. This ensures that the plunger head can seal well with the valve seat every time the plunger valve core 3 is closed.

[0050] In this embodiment, the return spring 4 is built into the central groove of the plunger rod. The plunger rod and the valve cap 1 have an upward opening from the bottom center to cooperate, which is used for the rebound sealing after the plunger valve core 3 is opened, so as to realize the single-flow control function. It should be emphasized that the built-in design of the return spring 4 can avoid the problem of hard oil wax, rubber blocks, wax blocks filling the gap of the return spring 4 and causing the spring to fail, and the plunger valve core 3 being unable to move upward or return to its original position.

[0051] In this embodiment, the valve cover 5 has an internal thread at the top for threaded connection with the valve cap 1; multiple openings C in the upper middle part for crude oil outflow, thereby allowing the crude oil lifted by the oil pump to flow into the return oil pipeline; an internal thread at the bottom for threaded connection with the vortex generating mechanism 8; and a groove at the bottom for embedding the lower sealing ring 7.

[0052] In this embodiment, the lower sealing ring 7 is embedded in the bottom groove of the valve cover 5 to seal the gap on the side of the valve cover 5 where crude oil from the oil pipe enters.

[0053] like Figure 4-1 , 4-2As shown in Figures 4-3 and 5, the swirl generating mechanism 8 is divided into two steps. The upper first step is threaded with external threads for threaded connection with the valve cover 5, and the top surface provides a seat cover for the plunger-type valve core 3. The lower second step contains the key structure of the swirl generating mechanism 8, which consists of a swirl vane and an olive-shaped or olive-like central shaft. Its structure is similar to the appearance structure of an aircraft engine. The difference is that the swirl vane and the olive-shaped or olive-like central shaft are an integral structure with the housing of the swirl generating mechanism 8 and do not rotate relative to each other.

[0054] In this embodiment, the swirl vanes are configured as 3-5 pieces, preferably 3 pieces, and these swirl vanes are preferably helical blades, and the helical blades are preferably helical hyperboloid blades, such as... Figure 6 As shown, the preferred structure of the helical hyperboloid blade is a helical hyperboloid blade with an inclination angle of 30 degrees to 41 degrees relative to the axis. This is because, according to computer fluid analysis results, when the blade inclination angle is 30-41°, as... Figure 7 As shown, the fluid flow rate is increased to achieve the best swirling effect while minimizing fluid resistance. This creates a high-speed fluid flow area at the sealing surface of the plunger valve core 3, causing the crude oil to move upward rapidly and generate a strong swirling flow. This swirling flow washes over the swirling mechanism 8 and the seat cover of the plunger head, achieving a self-cleaning function. The swirling channel formed between the swirling vanes is large enough for debris such as packing fragments and wax blocks to pass through. The crude oil flows at high speed through the swirling channel, achieving a certain flushing effect, and the debris will not accumulate here.

[0055] In this embodiment, the use of an olive-shaped or olive-like central shaft can generate a stronger and faster impact flow. This is because, according to calculations using fluid simulation software, the crude oil flows at high speed along the arc at the top of the olive-shaped or olive-like central shaft towards the first sealing surface between the plunger head slope and the swirl generator 8 housing as it flows from the top of the central shaft. This impacts the packing fragments and wax blocks and other debris accumulated there, further improving the flushing effect. In addition, it can also play a role in assisting in the diversion of crude oil.

[0056] In this embodiment, it should be emphasized that the lower step of the swirl generating mechanism 8 is spatially nested within the upper channel of the lower oil pipe, making full use of the space and providing more usable space for the setting of the "long plunger" structure, while ensuring a strong swirl generation effect.

[0057] The working process of the anti-backflow device at the wellhead of the pumping unit according to the embodiments of this disclosure is described below with reference to the accompanying drawings:

[0058] The specific operation involves replacing the flow valve at the pumping unit wellhead with an anti-backflow device. First, shut down the pumping unit, close the production valve and return valve, remove the flow valve, and then place the anti-backflow device at the pumping unit wellhead into the original flow valve installation position. Use a wrench to turn the octagonal nut on the top of the valve cap to install the anti-backflow device in place. Then, open the return valve and production valve and start the pumping unit to operate normally.

[0059] Crude oil enters the lower part of the anti-backflow device at the wellhead of the pumping unit through the tubing and the wellhead process. After passing through the vortex generator 8, it acts on the bottom of the plunger valve core 3. When the crude oil pressure is greater than the spring force of the return spring 4 and the return oil pressure, the plunger valve core 3 moves upward, compressing the return spring 4. The crude oil in the plunger valve core 3 flows out through the through hole B of the plunger valve core 3. The plunger valve core 3 continues to move upward and leaks out through the valve cover window C. The crude oil is subjected to a strong vortex generated by the vortex generator 8 to flush the inside of the valve cover 5, accelerating the outflow speed of the crude oil. When the crude oil pressure is less than the spring force of the return spring 4 and the return oil pressure, the return spring 4 rebounds, and the crude oil flows into the plunger valve core 3 through the through hole B. The plunger valve core 3 moves downward to reset, completing one single-flow control cycle.

[0060] During a certain operation, the inclined surface of the plunger valve core 3 and the top plane of the swirl generator 8 were blocked by packing debris, causing the plunger valve core 3 to fail to reset properly. The first seal formed by the contact surface between the inclined surface of the plunger valve core 3 and the swirl generator 8 failed. However, the "long plunger" design of the vertical surface of the plunger valve core 3 played a role. Part of the head of the plunger valve core 3 had entered below the valve cover window C, and the single-flow control function was still effective. In particular, the shuttle-shaped rubber ring 6 entered below the valve cover window C, which strengthened the seal and prevented backflow.

[0061] When the crude oil pressure exceeds the spring force of the return spring 4 and the return oil pressure again, the plunger valve core 3 moves upward, compressing the return spring 4. The crude oil in the plunger valve core 3 flows out through the through hole B of the plunger valve core 3. The plunger valve core 3 continues to move upward and leaks out of the valve cover window C. The crude oil is subjected to a strong swirling flow generated by the swirling mechanism 8 to flush the inside of the valve cover 5, and flushes the rubber block out of the valve cover window C and into the return oil pipeline, thus achieving a self-cleaning effect.

[0062] When the crude oil pressure is less than the spring force of the return spring 4 and the return oil pressure, the return spring 4 rebounds, and the crude oil flows into the cavity of the plunger valve core 3 through the through hole B. The plunger valve core 3 moves downward to reset, completing another single-flow control. No backflow occurs during the entire process.

[0063] In summary, the anti-backflow device for the pumping unit wellhead process of the present invention prevents backflow primarily through a multi-seal anti-backflow method using a "long plunger" and a strong swirling self-cleaning debris removal method, wherein:

[0064] The aforementioned "long plunger" multi-seal anti-backflow method involves designing the plunger head as a "long plunger" structure. By increasing the length of the vertical surface of the plunger head and the fitting height below the valve cover window C, a multi-seal effect is achieved. Even if the bottom slope of the plunger head is blocked by debris such as rubber blocks or wax blocks, the plunger head can still maintain a seal even after part of it has entered below the valve cover window C. In particular, the vertical surface has a spindle-shaped groove with a spindle-shaped rubber ring 6, which serves as a reinforced seal for the anti-backflow device. This provides a strong guarantee that the seal will not fail even if the slope is blocked by debris. The design of the spindle-shaped rubber ring 6 allows the plunger valve core 3 to expand outward when it moves upward, scraping out the sand in the gap and preventing the plunger valve core 3 from being stuck by sand. When the plunger valve core 3 moves downward, it closes inward, making it easier to enter the lower space of the valve cover window C, strengthening the seal and achieving a multi-seal anti-backflow effect.

[0065] The described high-speed swirling self-cleaning impurity removal method involves installing a swirling mechanism 8 at the lower part of the plunger-type valve core 3. This mechanism, composed of swirling vanes and a rugby ball-shaped central shaft, causes the crude oil to rotate at high speed, thus cleaning impurities and achieving a self-cleaning effect. The swirling mechanism 8 is spatially nested within the lower oil pipe ascending channel, making full use of space and providing more usable space for the "long plunger" structure, while ensuring effective flushing and cleaning of the plunger-type valve core 3's seat surface. The rugby ball-shaped central shaft assists in diverting the crude oil. When impurities... When the material is pressed against the cover of the plunger-type valve core 3, the "long plunger" structure still effectively maintains single-flow control. During the upstroke of the pumping unit, the crude oil moves upward and will still be pressurized at the cover of the plunger-type valve core 3. When the pressure is greater than the spring force of the return spring 4 and the return oil pressure, the plunger-type valve core 3 moves upward and opens. During the flow of crude oil to the return oil line, the flowability of crude oil is changed by the swirling mechanism 8, which enhances the swirling flushing effect and flow speed. It automatically flushes away impurities and enters the return oil line with the crude oil, and will not accumulate at the cover of the plunger-type valve core 3, thus achieving a self-cleaning effect.

[0066] In the application phase of the "long plunger" multi-seal anti-backflow method, crude oil pushes the plunger valve core upward. Crude oil mixed with impurities is accelerated by the rotation of the vortex generator 8 and enters the return oil line through the valve cover opening. The return spring pushes the plunger downward, and the impurities cushion the seat surface where the plunger valve core contacts the vortex generator. Under the "long plunger" multi-seal effect, the single-flow control remains effective, and backflow will not occur. Then, in the application phase of the strong vortex self-cleaning impurity removal method, crude oil pushes the plunger valve core upward again. Crude oil mixed with impurities is accelerated by the rotation of the vortex generator to flush away the impurities that previously cushioned the plunger valve core, and together they enter the return oil line through the valve cover opening, achieving self-cleaning. The return spring pushes the plunger valve core downward to reset. After the strong vortex self-cleaning impurity removal method application phase is completed, the "long plunger" multi-seal anti-backflow method application phase is restarted.

[0067] The anti-backflow device for the pumping unit wellhead process disclosed herein has the following advantages compared to the prior art:

[0068] Beneficial effects:

[0069] 1) The vortex generator produces a strong and fast vortex with a strong flushing and carrying effect and a good self-cleaning effect. The vortex generator is nested inside the lower oil pipe, which rationally allocates the functions in space.

[0070] 2) The plunger-type valve core is designed to still achieve a seating effect even when the bottom is blocked by debris, and the single-flow control function is still effective. In particular, the shuttle-shaped rubber ring design enhances the seating effect, prevents crude oil from backflowing, and can remove debris on its own.

[0071] 3) Debris is flushed and carried into the return oil pipeline, and will not remain on the plunger seat cover. Regular cleaning is not required, reducing maintenance workload and lowering the risk of wellhead packing leakage.

[0072] 4) The application of this anti-backflow device in the field does not require adjustment of the wellhead process flow. Only the single-flow valve needs to be replaced. The process modification is simple, the cost is low, and the application range is wide.

[0073] The various embodiments of this disclosure have been described above. These descriptions are exemplary and not exhaustive, and are not 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 applications, or technical improvements to the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A backflow prevention device for a pumping unit wellhead process, comprising a check valve disposed between the tubing and the return pipeline, characterized in that: The inlet of the single-flow valve is connected to a swirling mechanism (8). The swirling mechanism (8) includes a housing connected to the inlet. The housing contains an integrally fixed central shaft and at least one swirling vane. The central shaft is olive-shaped or olive-like, and a swirling channel for crude oil is formed between two adjacent swirling vanes.

2. The anti-backflow device for the pumping unit wellhead process according to claim 1, characterized in that: The swirl vanes are helical blades, and the number of vanes is 3 to 5.

3. The anti-backflow device for the pumping unit wellhead process according to claim 2, characterized in that: The helical blades are helical hyperboloid blades, and the number of blades is 3.

4. The anti-backflow device for the pumping unit wellhead process according to claim 3, characterized in that: The helical blade is a hyperboloidal helical blade with an inclination angle of 30° to 41° relative to the axis.

5. The anti-backflow device for the pumping unit wellhead process according to any one of claims 1-4, characterized in that: The lower part of the housing of the swirl generating mechanism (8) is nested in the rising channel of the oil pipe.

6. The anti-backflow device for the pumping unit wellhead process according to claim 5, characterized in that: The single-flow valve includes a valve body, a plunger-type valve core (3) and a return spring (4). The inlet and outlet of the valve body are respectively connected to the oil pipe and the return oil line. The plunger valve core (3) includes a plunger head and a plunger rod. The plunger rod is provided with a central groove, and a return spring (4) is fitted through the central groove. During the upstroke of the pumping unit, the hydraulic pressure of the oil pipe and the rebound force of the return spring (4) during the downstroke of the pumping unit drive the plunger head to move up or down relative to the valve body to open or close the return oil line.

7. The anti-backflow device for the pumping unit wellhead process according to claim 6, characterized in that: The lower part of the plunger head is provided with a spindle-shaped groove, and a spindle-shaped seal is fitted inside the spindle-shaped groove.

8. The anti-backflow device for the pumping unit wellhead process according to claim 7, characterized in that: The shuttle-shaped seal is a shuttle-shaped rubber ring.

9. The anti-backflow device for the pumping unit wellhead process according to any one of claims 6-8, characterized in that: The bottom of the plunger head has a conical structure; The cone structure forms a surface seal or line seal with the upper port of the housing of the vortex generating mechanism (8).

10. The anti-backflow device for the pumping unit wellhead process according to claim 9, characterized in that: The valve body includes a valve cover (5), and a valve cap (1) is connected to the top of the valve cover (5); A window is opened on the side of the valve cover (5) to serve as the outlet of the valve body; The valve cap (1) has a travel guide for the plunger rod, and the side of the central groove of the plunger rod has a through hole. During the upstroke or downstroke of the pumping unit, the through hole communicates with the valve cavity of the valve body.

11. The anti-backflow device for the pumping unit wellhead process according to claim 10, characterized in that: Sealing rings are respectively provided on the upper part of the valve cover (5) and the bottom end face of the valve cover (5).

12. A method for preventing backflow at the wellhead of an oil pumping unit, characterized in that, include: The lower part of the shell of the vortex generator (8) of the anti-backflow device for the pumping unit wellhead process according to any one of claims 1-11 is nested in the rising channel of the oil pipe, and the outlet of the single-flow valve is connected to the outlet pipeline of the pumping unit wellhead.

13. The method for preventing backflow at the wellhead of an oil pumping unit according to claim 12, characterized in that: The one-way valve includes a plunger valve core (3) and a return spring (4). During the upstroke of the pumping unit, crude oil mixed with impurities flows from the oil pipe through the swirling mechanism (8) and acts on the bottom of the plunger valve core (3), pushing the plunger valve core (3) upward and compressing the return spring (4) to open the one-way valve. The crude oil flows into the return oil line. At the same time, the swirling channel accelerates the outflow speed of the crude oil to flush away the impurities that affect the closing of the plunger valve core (3) and flow into the return oil line along with the crude oil. When the pumping unit enters the downstroke, the crude oil pressure is less than the spring force of the return spring (4) and the return oil pressure. The return spring (4) rebounds, and the plunger valve core (3) moves down to reset, closing the one-way valve.

14. The method for preventing backflow at the wellhead of an oil pumping unit according to claim 13, characterized in that: The plunger valve core (3) includes a plunger head and a plunger rod. A shuttle-shaped seal is provided at the lower part of the plunger head. During the upstroke of the pumping unit, the shuttle-shaped seal scrapes the valve cavity wall of the single-flow valve to prevent the plunger valve core (3) from getting stuck. During the upstroke of the pumping unit, the plunger head is guided to move down to reset and set.

15. The method for preventing backflow at the wellhead of an oil pumping unit according to claim 14, characterized in that: The plunger rod is provided with a central groove, and the return spring (4) is fitted through the central groove. A through hole is opened on the side of the central groove. The valve body of the single-flow valve is provided with a piston rod stroke guide rail. The central groove and the stroke guide rail form an independent chamber. When the plunger valve core (3) moves upward, the crude oil in the independent chamber flows out through the through hole.

16. The method for preventing backflow at the wellhead of an oil pumping unit according to claim 15, characterized in that: The bottom of the plunger valve core (3) is a cone structure. The cone structure forms a surface seal or line seal with the upper port of the housing of the vortex generating mechanism (8). If there are foreign objects between the cone structure and the upper port of the housing, the surface seal or line seal fails. The plunger valve core (3) uses the plunger head and the shuttle-shaped seal to perform seat sealing to prevent backflow.

Images