RU2736101C1 - Well rod pumping assembly (embodiments) - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: invention relates to the field of machine building. Downhole sucker-rod pump unit comprises a fixed part and a rod string connected to the lifting pipe, a movable part of the pump, a drive for transfer of reciprocating or rotary motion to the rod string. Fixed part from above is provided with coaxially installed branch pipe. Check valve is installed above fixed part, check valve seat is arranged in branch pipe. Shut-off element is installed on the lower rod with guaranteed clearance with the possibility of limited axial movement and interaction with the seat. Shut-off element contains the lower support part and the cover, at the same time in one of them there is a blind cylindrical cavity with the sealing unit installed in it. Support part is equipped with stop interacting with cover, check valve arranged in lower part of lifting pipe. Shut-off element is fitted on the rod with a guaranteed radial clearance. Cover is installed with the possibility of the axial movement limited with the additional support relative to the lower support part, which is made in the form of a collar or support surface formed by boring in the upper part of the cylindrical recess of the lower support part.

EFFECT: invention can be used in oil producing industry in borehole sucker-rod pumps.

5 cl, 5 dwg

Description

The invention relates to the field of mechanical engineering, to downhole sucker rod pumps, and can be used in the oil industry.

Known sucker rod pumping unit (Catalog "Borehole sucker rod pumps for oil production" TsINTIKHimneftemash, M. 1988, p. 22), containing a working cylinder connected to the string of lifting pipes, inside of which a hollow plunger with a pressure valve, connected to the string, moves with a minimum clearance sucker rods, a suction valve is installed at the bottom of the cylinder.

The disadvantage of the known sucker rod pump is a decrease in the liquid level in the lifting pipe string, for example, tubing (tubing), when the pump is stopped when the suction valve is not completely tight. Fluid leaks from riser pipes lead to increased energy consumption and a decrease in the volume of produced fluid.

Pump shutdown can be caused by drive faults, as well as by periodic well operation. Depending on leakage rate, suspension depth and pump shutdown time, the liquid level in the riser pipe may drop to a static level.

Known sucker rod pumping unit containing a working cylinder connected to the lifting pipe string, inside which a hollow plunger with two discharge valves moves with a minimum clearance in the lower and upper parts of the plunger, connected to the sucker rod string, a suction valve is installed in the lower part of the cylinder (see Book: Molchanov G.V., Molchanov A.G. Machines and equipment for oil and gas production. Textbook for universities. - M., Nedra, 1984, p. 114, Fig. V. 5, b).

Equipping the plunger with two check valves reduces volumetric losses due to a decrease in the harmful cylinder volume, as well as leaks through the discharge valves.

The disadvantage of the known sucker rod pump is a decrease in the liquid level in the lifting pipe string when the pump is stopped with incomplete tightness of the suction valve. Fluid leaks from riser pipes lead to increased energy consumption and a decrease in the volume of produced fluid.

Violation of the tightness of the suction valve can occur when mechanical inclusions enter between the shut-off element and the seat, valve wear.

Known sucker rod pumping unit containing a cylinder and a hollow plunger, including interconnected stages of the cylinder and plunger of large and small diameter to form a chamber of variable volume between the stages of the plunger, a suction valve located in the lower part of the plunger and a discharge valve installed with the possibility of separating the cavities of the stages plunger (see RF patent No. 2620183, F04B 47 | 02, publ. 05/23/2017, bul. No. 15).

The disadvantage of the known pump is the emptying of liquid from the tubing through the gaps between the stages of the cylinder and the plunger when the pump is stopped.

Known downhole sucker rod pumping unit, including a screw pump containing a stationary stator connected to a lifting pipe, and a movable rotor connected to a rotating rod string (see book: Baldenko F.D., Krivenkov S.V., Protasov V.N. . Installation and operation of downhole sucker-rod pumping units. Textbook. - M., Gubkin Russian State University of Oil and Gas, 2017, p. 6, Fig. 1), which is taken as a prototype.

The disadvantages of the pumping unit are the emptying of the liquid inside the riser pipe to a static level when the pump stops due to the presence of a gap between the stationary part (stator) and the moving part (rotor). The clearance increases during pump operation due to wear of the stator and rotor working surfaces.

Known pump containing a cylinder connected to the lifting pipe, which houses a plunger rigidly connected to the string of rods, a check valve located in the lower part of the lifting pipe, the shut-off element of which is mounted on the lower rod with the possibility of limited axial movement and interaction of its support-sealing a surface with a saddle mounted on a riser pipe includes a body in which a blind cylindrical recess is made with a sealing unit placed in it and a cover interacting with the stop (see RF patent No. 2674843, F04B 47/00, F04B 15/00. Pump. Publ. 13.12.2018, bul. No. 35), which was taken as a prototype.

In the known device, the shut-off element is sealed on the upper rod and interacts with the seat during the downward movement of the rod string, as well as when the pump is stopped. In this case, the sealing unit of the shut-off body constantly experiences friction, and the lower support-sealing surface and the seat constantly experience cyclic loading.

Constant wear of the seating surface of the body, seat, and the rod seal assembly does not exclude fluid leakage through the check valve when the pump stops.

The disadvantages of the pumping unit are liquid leaks from the riser through the check valve when the pump is stopped, which leads to additional energy costs for filling the riser channel with liquid and an increase in the downtime of the well.

The technical task of the proposed technical solution is to reduce energy losses and downtime.

The solution to the technical problem is achieved by the fact that in a downhole sucker rod pumping unit containing a pump plunger connected respectively to the riser pipe and a rod string, a drive for transferring a reciprocating rod string, a cylinder equipped with a coaxially installed branch pipe on top, a check valve installed above the cylinder, the check valve seat, located in the branch pipe, and the shut-off element is installed with the possibility of limited axial movement and interaction with the saddle, and contains a lower support part and. cover, while in one of them there is a blind cylindrical recess with a sealing unit placed in it, the support part is equipped with a stop interacting with the cover, according to the technical solution, the check valve locking element is installed with a guaranteed radial clearance, the cover is installed with the possibility of an axial displacement relative to the lower support part made in the form of a shoulder or support surface formed by a bore in the upper part of the cylindrical recess of the lower support part.

The shut-off element is installed on the rod.

In the case of a pumping unit with a differential sucker rod pump, the shut-off element is installed on the plunger.

The solution to the technical problem is achieved by the fact that in a borehole sucker rod pumping unit containing a stator and a rotating rod string connected to the riser pipe, respectively, connected to the pump rotor, a drive for transmitting rotational motion to the rod string, a stator provided from above with a coaxially installed branch pipe, a check valve installed above the stator, the check valve seat is located in the branch pipe, and the shut-off element is installed with the possibility of limited axial movement and interaction with the seat, and contains a lower support part and a cover, while one of them has a blind cylindrical recess with a sealing unit located in it, the support part equipped with a stop interacting with the cover, according to the technical solution, the check valve shut-off element is installed with a guaranteed radial clearance, the cover is installed with the possibility of axial movement limited by an additional stop relative to the lower support part, made in the form of a shoulder or a support surface formed by a bore in the upper part of the cylindrical recess of the lower support part.

The sealing unit in the cylindrical groove is installed with guaranteed interference with respect to its lateral surface.

The design of the proposed device is illustrated by a drawing.

FIG. 1 shows a diagram of a downhole sucker rod pumping unit;

FIG. 2 - pump unit check valve assembly;

FIG. 3 - version of the check valve;

FIG. 4 is a diagram of equipping a differential sucker rod pump with the proposed check valve;

FIG. 5 is a diagram of a downhole sucker rod pumping unit.

The downhole sucker rod pumping unit contains a cylinder 1 (see Fig. 1), connected, for example, by means of a branch pipe 2, with a riser pipe 3. Inside the cylinder 1, for example, with a small gap, a hollow plunger 4 is installed, in the lower part of which there is a discharge valve 5. A suction valve 6 is installed in the lower part of the cylinder 1 to form a working cavity 7 of the pump. The plunger 4 is connected to the rod string 8.

The branch pipe 2 with the cylinder 1 and the riser pipe 3 is connected, for example, by means of couplings (not shown in the figure).

For example, the rod 9 of the column of rods 8 is equipped with a check valve shut-off element 10 (Fig. 2) with a central hole 11 mounted on it. The shut-off element 10 on the rod 9 is installed with a guaranteed gap (not shown in the figure), and contains a lower support part 12 and cover 13.

In the lower support part 12 and the cover 13, a blind cylindrical recess 14 or a protrusion 15 is made in response to each other with the formation of a cavity 16 of variable volume between the end surfaces of the recess 14 and the protrusion 15, and the side surfaces of the recess 14 and the rod 9. In the cavity 16 between the end surfaces of the recess 14 and the projection 15, a sealing assembly is placed, including, for example, the lower 17, the upper 18 thrust rings and the middle sealing ring 19. The cover 13 is mounted with the possibility of limited axial movement relative to the support part 12.

The O-ring 19 is made of an elastic material such as rubber, and the lower 17 and upper 18 rings are made of a harder material with a low coefficient of friction, such as PTFE.

The axial movement of the cover 13 is limited by stops 20 and 21, made, for example, respectively, in the form of a shoulder below the cylindrical protrusion 15 in the support part 12, and the pins. The pins 21 are installed, for example, in blind radial holes (not shown in the figure), made, for example, in the support part 12 with the same angular distance between them. In the cover 13, opposite the pins 21, through longitudinal grooves 22 are made, the height of which is greater than the diameter of the pins 21. The difference in the height of the grooves 22 and the diameter of the pin 21 is greater than the maximum distance between the end of the cover 13 and the shoulder 20.

A part of the inner side surface of the adapter 2, below the shut-off element 10, is made, for example, conical, on which a check valve seat 23 is fitted, which is designed in response to the shut-off element 10, with the possibility of interaction with the support-sealing surface 24 of the support part 12, made, for example, spherical. The sealing surface 25 of the seat 23 can be tapered. In this case, the angle between the conical surface and the vertical is taken to be greater than the friction angle, which is 10-12 °.

In the branch pipe 2, above the conical surface, for example, a cylindrical bore is made to form an annular support surface 26, and in the saddle 23, corresponding to it, a collar 27 is made with the possibility of its interaction with the support surface 26.

The rings 17, 18 and 19 relative to the rod 9 are installed with a guaranteed clearance (not shown in the figure), and in the cylindrical recess 14 they can be installed with a slight interference.

The maximum distance between the ends of the recess 14 and the projection 15 is less than the total height of the rings 17, 18 and 19 to ensure a small preliminary compression.

The gap between the mating side surfaces of the recess 14 and the projection 15 can be sealed with an O-ring 28 installed, for example, in the annular groove (not shown in the figure) of the cover 13.

The rod 9 can be made with high precision and with a polished surface.

A blind cylindrical recess 14 (Fig. 3) can be made in the lower support part 12. The cover 29 is made in the form of an annular plate, and the stop 20 is in the form of a spring split ring. The stop 21 is made in the form of a horizontal annular surface formed by a bore of a larger diameter (not shown in the figure) in the upper part of the recess 15.

The pumping unit can be equipped with a differential sucker rod pump, which includes cylinders of small 30 (Fig. 4) and large 31 diameters connected by a sub 32. Plungers of small 33 and large 34 diameters are installed in cylinders 30 and 31 with a guaranteed clearance, respectively, connected by a sub 35, to form chambers 36 of variable volume between the subs 32 and 35. For example, a suction valve 6 is installed in the lower part of the plunger 34, and a discharge valve 5 is installed in the plunger 33 to form the working cavity 7 and with the possibility of separating the internal cavities (not shown in the figure) of the plungers 33 and 34.

In the upper part, the cylinder 30 is equipped with a coaxially installed branch pipe 2, the inner diameter of the lower part of which, for example, is equal to the diameter of the cylinder 30. On the plunger 33 with a guaranteed clearance (not shown in the figure) there is a check valve shut-off element 10, in which the stop 20 of the cover 29 made in the form of a nut. In the upper part of the branch pipe 2, a cylindrical bore (not shown in the figure) of a larger diameter is made. For example, in the bore of the branch pipe 2, in response to the support part 12 of the shut-off member 10, a saddle 37 is made with a conical thrust-sealing surface (not shown in the figure).

The sub 35 has at least one radial through hole 38 that communicates the working cavity 7 with the chamber 36 of variable volume.

The differential pump is lowered, for example, in the tubing 3.

The downhole sucker rod pumping unit (Fig. 5) includes a fixed part of the stator 39, connected to the lifting pipe (tubing) 3 by means of a branch pipe 2. The movable part of the screw pump, the rotor 40, for example, by means of a cam coupling 41, is connected to the rod 9 of the rotating string of rods 8 The shut-off element 10 with a central through cylindrical hole is mounted on the rod 9.

A part of the inner side surface of the branch pipe 2, below the shut-off element 10 (see Fig. 3), is made, for example, conical, on which a counter-made saddle 23 of the check valve is fitted with the possibility of interacting with the support-sealing surface 24 of the support part 12.

In the branch pipe 2, above the conical surface, for example, a cylindrical bore is made to form an annular support surface 26, and in the saddle 23, corresponding to it, a collar 27 is made with the possibility of its interaction with the support surface 26.

A centralizer 42 can be mounted on the rod 9 below the saddle 23.

The supporting part 12 of the shut-off element 10 can also be equipped with a centralizer 43 to ensure the alignment of the rod string and the riser pipe, as well as the exact fit of the shut-off element 10 on the seat 23.

The pump is lowered and lifted as follows.

If the pump is tubular (Fig. 1), the cylinder 1 is lowered with the riser pipe 3. When the plunger 4 is lowered above it, the saddle 23 is mounted on the rod 9, then the shut-off element 10. At the end of the descent of the string of rods 8 with the plunger 4, the saddle 23 is fitted in response made conical surface (not shown in the figure) in the pipe 2.

When lifting the string of rods 8, the separation of the saddle 23 from the adapter is carried out under the action of the plunger 4. When the support surface 26 and the collar 27 are made in the nozzle 2 and the saddle 23, a significant axial load acting on the shut-off element 10 is perceived by them. This significantly reduces the force on the separation of the seat 23.

The lowering of the plug-in differential pump (Fig. 4) is carried out by a column of rods (not shown in the Fig.) In assembled form.

The descent and ascent of the rod string 8 with the rotor 40 (Fig. 5) is carried out in a similar way.

The device works as follows.

Let the plunger 4 be in the lower position (Fig. 1) and the suction cycle is carried out. Discharge valve 5 is closed and suction valve 6 is open. When the plunger 4 moves up, the pressure in the working cavity 7 decreases. Liquid, for example, from the reservoir (not shown in the figure) through valve 6 enters the working cavity 7. During the stroke of the plunger 4 upwards, during the suction and discharge cycle, the liquid rises through the channel of the riser pipe 3. Under the action of the pressure drop, the shut-off element 10 the check valve is lifted above the seat 23. Since the shut-off element 10, as well as the rings 17-19 relative to the rod, are installed with a guaranteed clearance, only liquid friction occurs between the shut-off body 10 and the rod 9.

When the plunger 4 moves down, the valve 5 opens and the suction valve 6 closes. The volume of the working cavity 7 decreases, and the liquid flows through the valve 5 into the cavity (not shown in the figure) between the valves 5 and 10. A part of the liquid from the specified cavity, displaced by the volume of the lowered part of the rod 9, flows through the check valve with the raised shut-off organ 10 into the channel of the riser pipe 3 (not shown in the figure).

Thus, when the rod string 8 moves up and down, the check valve shut-off element 10 is always raised above the seat 23. There is no contact of the shut-off element 10 with the rod 9, which eliminates friction and wear of the rod 9 and the sealing ring 19 of the shut-off element 10.

When the pump stops, the suction 6 and discharge 5 valves are closed. Under the action of the weight, the shut-off element 10 is also lowered onto the seat 23. In the presence of liquid leaks through the suction valve 6, the liquid from the working cavity 7 begins to flow back into the well. With a decrease in pressure in the cavity 7, the plunger 4 goes down, reducing the pressure under the shut-off element 10 through the guaranteed gap (not shown in the figure) between the rings 17-19 and the rod 9. The cover 13, under the influence of the pressure drop, goes down, compressing the O-ring 19. When the ring 19 is axially compressed, its inner diameter decreases and compresses the rod 9. At a considerable depth of the pump suspension, when the pressure of the liquid column on the shut-off body is high, the lower end (not shown in the figure) of the cover 13 can interact with the stop 20, preventing excessive loading O-ring 19. When the cover 13 is displaced downward, the lower walls (not shown in the figure) of the grooves 22 move away from the pins 21.

Subsequently, the fluid pressure under the shut-off element 10 of the check valve is equalized with the well pressure. And the inner channel of the riser pipe 3 remains completely filled.

When the pump is turned back on, the fluid supply to the surface resumes immediately.

The stroke of the cover 13 is selected from the condition of complete filling with the radially expanding sealing ring 19 of the gap between it and the rod 9.

The difference in the height of the radial through grooves 22 and the diameter of the pins 21 is chosen more than the stroke of the cover 13 in order to exclude the perception of the axial load by the pins 21 and to avoid excessive deformation of the sealing ring 19.

The operation of the shut-off element 10 (Fig. 3), in which the blind cylindrical recess 15 is made in the lower support part 12, is similar. When the shut-off body 10 fits onto the seat 23, with a decrease in pressure under it, the cover 29 moves downward, compressing the rings 17-19.

Thus, equipping the downhole sucker rod pumping unit with a check valve, the shut-off element of which is mounted on the lower rod, ensures that liquid leaks from the riser pipe are excluded when the pump stops when the suction valve is tight.

With the stroke of the plungers 33 and 34 downward (Fig. 4), as the volume of the chamber 36 increases, the pressure in it decreases. The suction valve 6 is open, and the discharge valve 5 is closed. The supporting part 12 of the shut-off member 10, under the influence of its weight, interacts with the seat 37. Part of the liquid from the tubing string 3 through the gaps (not shown in the figure) between the plunger 33 and the shut-off member 10, as well as the cylinder 30, begins to flow into the chamber 36. Further, under the action of a pressure drop, the upper ring 18 moves downward, deforming the elastic sealing ring 19. With decreasing height, the inner diameter of the ring 19 decreases, sealing the gap between the plunger 33 and the shut-off element 10.

The size of the gap between the shut-off element 10 and the plunger 33 is comparable to the gap between the plunger 33 and the cylinder 30. Due to the small height of the shut-off element compared to the length of the cylinder 30, the pressure drop in the shut-off element 10 is a small fraction of the total pressure drop. As a result, the contact pressure in the seal ring 19 is also low. Therefore, the friction force and wear of the sealing ring 19 of the shut-off element 10 are small. When the plungers 33 and 34 move upward, the suction valve 6 closes, and the delivery valve 5 opens.

Then the cycle is repeated.

When the differential pump is stopped (Fig. 4), the shut-off element 10 seals the gap between the plunger 33 and the cylinder 30, preventing the liquid from emptying from the tubing string.

During operation of the screw pump (Fig. 5), the shut-off element 10 is in a position raised above the seat 23. When the pump stops, the shut-off element 10 is lowered onto the seat 23. Since there is usually a gap between the stator 39 and the rotor 40, and the liquid from the cavity (not shown in the figure) between the pump and the check valve 10 flows back into the well. Further, under the influence of the differential pressure, the O-ring 19 seals the gap between it and the rod 9, and it is prevented from emptying the liquid from the tubing string 3 back into the well.

The cam clutch 41 and the centralizer 42 provide rotation of the rod 9 and the string of rods 8 without radial runout. When equipping the shut-off element 10 with an additional centralizer 43, the accuracy of the fit of the shut-off element 10 on the seat 23 is ensured.

Thus, equipping the downhole sucker rod pumping unit with a check valve, the shut-off element of which is mounted on the rod with a guaranteed clearance, ensures that liquid leaks from the lifting pipe (tubing) are excluded when the screw pump stops. In addition, it is possible to control the tightness of the tubing string after running the pump.

When equipping a differential pump, in which the liquid in the tubing string is constantly communicating with the pump inlet through the gaps between the stages of the cylinder and the plunger, it is possible to pressurize the tubing string, as well as eliminate liquid leaks through the gaps between the stages of the plunger and cylinder when the pump is stopped. In addition, the check valve helps reduce fluid leakage through the gaps between the cylinder and the small bore plunger on the downstroke of the plungers.

Claims (5)

1. Downhole sucker rod pumping unit, containing a pump plunger connected respectively to the riser pipe and a rod string, a drive for transmitting reciprocating motion to the rod string, a cylinder equipped with a coaxially installed branch pipe on top, a check valve installed above the cylinder, a check valve seat located in the branch pipe, and the shut-off element is installed with the possibility of limited axial movement and interaction with the seat and contains a lower support part and a cover, while in one of them there is a blind cylindrical recess with a sealing unit located in it, the support part is equipped with a stop interacting with the cover, characterized in that the shut-off element of the check valve is installed with a guaranteed radial clearance, the cover is installed with the possibility of axial movement limited by an additional stop relative to the lower support part, made in the form of a shoulder or a support surface formed by a bore in the upper part of the lindrical recess of the lower support part. 2. Pumping unit according to claim 1, characterized in that the shut-off element is mounted on the rod. 3. Pumping unit according to claim 1, characterized in that in the case of a pumping unit with a differential sucker rod pump, the shut-off element is installed on the plunger. 4. Downhole sucker rod pumping unit containing a stator connected to the riser pipe and a rotating rod string connected to the pump rotor, a drive for transmitting rotational motion to the rod string, a stator fitted from above with a coaxially installed branch pipe, a check valve installed above the stator, a check valve seat is placed in the branch pipe, and the shut-off element is installed with the possibility of limited axial movement and interaction with the saddle, and contains a lower support part and a cover, while in one of them there is a blind cylindrical recess with a sealing unit placed in it, the support part is equipped with a stop interacting with the cover , characterized in that the check valve shut-off element is installed with a guaranteed radial clearance, the cover is installed with the possibility of axial movement limited by an additional stop relative to the lower support part, made in the form of a shoulder or a support surface formed by a bore in the upper part Part of the cylindrical recess of the lower support part. 5. Pumping unit according to claim 1 or 4, characterized in that the sealing unit in the cylindrical recess is installed with a guaranteed interference with respect to its lateral surface.

Images