RU2731328C1 - Bottom-hole sucker-rod pump - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: invention relates to machine building, particularly, to vertical plunger pumps with self-acting valves for transfer of highly viscous liquids containing mechanical impurities and gas, in particular to downhole sucker-rod pumps. Downhole sucker-rod pump comprises composite cylinder and plunger, comprising steps of large and small diameter connected by adapters. Plunger is arranged in the cylinder to form a variable-volume chamber between the adapters. Suction and discharge valves are installed in plunger with possibility to disconnect inner cavities of stages. Suction valve includes upper and lower seats. Locking element is made in the form of a bushing with an upper collar mating the upper seat and is installed with the possibility of limited axial movement with provision of simultaneous interaction with the seats. On inlet of delivery valve cylindrical cavity with end surface is made. Plunger is equipped with branch pipe with collar in lower part mating with bore holes and cylindrical cavity with formation of lower chamber of variable volume. In upper part of branch pipe there is at least one through radial hole with possibility of its partial coverage by cylindrical recess side surface in upper position of bushing.

EFFECT: invention can be used in oil industry.

4 cl, 6 dwg

Description

The invention relates to the field of mechanical engineering, in particular to vertical plunger pumps with self-acting valves, especially for pumping high-viscosity liquids containing mechanical impurities and gas, in particular to downhole sucker rod pumps, and can be used in the oil industry.

A well-known sucker rod pump (Catalog "Downhole sucker rod pumps for oil production" TsINTIKHimneftemash, M. 1988, p. 22), containing a working cylinder, inside which a hollow plunger with a discharge valve moves with a minimum clearance, connected to the sucker rod string, in the lower part cylinder is fitted with a suction valve.

The disadvantages of the known sucker rod pump are unacceptable volumetric losses due to insufficient flow capacity, delayed opening and closing of the suction valve, as well as the likelihood of loss of stability and sagging of the rod string bottom.

Known downhole sucker rod pump containing a cylinder, a stepped plunger with a discharge valve, a suction valve with a shut-off element made in the form of a sleeve, in response to the lower part of the plunger with the possibility of limited axial movement and the formation of a chamber of variable volume (see RF Patent No. 2669058, MCP F04B 47 / 00, 2018) which is taken as a prototype.

The disadvantages of the known device are the delay in closing the suction valve due to its closing only from its weight, as well as the possibility of loss of stability and sagging of the bottom of the rod string.

The technical objective of the present invention is to reduce volumetric losses by reducing the closing lag of the suction valve and ensuring regulation of the load on the shut-off element.

The solution to the technical problem is achieved by the fact that in a downhole sucker rod pump containing a cylinder, a suction valve including upper and lower seats, a shut-off element made in the form of a sleeve with an upper shoulder in response to the upper seat, the lower seat is located in the bottom of the pump with a through axial hole, a plunger with steps of large and small diameter with a discharge valve, the sleeve is installed with the possibility of axial movement limited by the stop along the plunger with the formation of a chamber of variable volume formed by the end of the sleeve, a stage of a small diameter plunger and a cylinder, according to the technical solution, the cylinder is made in steps of large and small diameter in response to the steps plunger, the lower seat is connected to the plunger, in the lower part of which, above the lower seat, at least one through radial hole is made with the possibility of communicating with the axial hole of the bottom, the inlet of the discharge valve is made in the form of a cylindrical recess with an end surface, the plunger is provided with wives with a branch pipe with a collar in the lower part in response to the bushing holes and a cylindrical recess with the possibility of interaction of the collar with the end of the bushing, at least one through radial hole is made in the upper part of the branch pipe with the possibility of its partial overlap by the lateral surface of the cylindrical recess in the upper position of the bushing.

The small-diameter plunger in the lower part is equipped with a central branch with a discharge valve located in it.

The branch pipe in the lower part is made with a larger diameter, and the length of the upper section is greater than the total height of the cylindrical recess and the maximum stroke of the sleeve.

The branch pipe is equipped with at least one counterweight made in the form of a ring mounted on it.

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

FIG. 1 shows a diagram of a downhole sucker rod pump;

FIG. 2 - section a-a in Fig. 1;

FIG. 3- section b-b in Fig. 1;

FIG. 4 - pump with a branch pipe with increased weight;

FIG. 5 - an embodiment of a pump with a small harmful cylinder volume;

FIG. 6 - section b-b in fig. five.

The downhole sucker rod pump contains a composite cylinder 1 (see Fig. 1), including an upper cylinder 2 of a small and a lower cylinder 3 of a larger diameter, interconnected, for example, a sub 4, a plunger 5, consisting of an upper plunger 6 of a small diameter and a lower plunger 7 large diameter, connected, for example, by a sub 8, reciprocally made, respectively, of cylinders of smaller 2 and large 3 diameters.

In the lower part of the plunger 7 of large diameter, for example, three through radial holes 9 (Fig. 2) are made, located at an equal angular distance between them. The holes 9 can be made in the form of a rectangle in plan.

The lower plunger 7 in the lower part, above the radial holes 9, is provided with an upper seat 10, made, for example, in the form of a shoulder. The plunger 7 in the lower part is equipped with a bottom 11, including a lower seat 12, made, for example, in the form of a disk with through central (not shown in the figure) and peripheral axial holes 13 (Fig. 3), a stop 14, made, for example, in in the form of a disk with a central threaded hole (not shown in the figure) and connected to the plunger 7 by means of a threaded connection (not shown in the figure). The stop 14 is installed below the seat 12 with a guaranteed axial clearance (not shown in the figure). The saddle 12 has, for example, a central through hole (not shown in the figure). The stop 14 is installed with the ability to interact with the saddle 12 by means of an adjusting bolt 15 with a locknut 16. In the upper part of the bolt 15, a cylindrical protrusion 17 is made, corresponding to the central hole of the saddle 12. The bottom 11 is connected to the bolt 15 by means of a washer and a spring split ring installed in the cylindrical groove (not shown in the figure) of the projection 17.

Through holes 13 of the seat 12 are made with the possibility of communicating with the radial holes 9 of the plunger 7. In the stop 14, in response to the holes 13 of the seat 12 and with the possibility of communication with them, through axial holes 18 are made.

In the plunger 7, above the seat 12, a shut-off element 19 of the suction valve is installed, made in the form of a sleeve with a shoulder 20 in the upper part. In this case, the collar 20 and the side surface of the sleeve 19 are made in response to the inner surface (not shown in the figure) of the plunger 7 and the shoulder 10.

In the shoulder 20 and in the lower part of the sleeve 19, there are thrust-sealing surfaces 21 and 22, which are reciprocally made to the seats 10 and 12 with the possibility of simultaneous interaction with them. The thrust-sealing surfaces 21 and 22 can be spherical, and the mating surfaces of the seats 10 and 12 can be conical, with the possibility of touching the mating pairs along the line. At the same time, in order to ensure sufficient force on the contact surfaces, the contact of the surface 21 and the seat 10 is carried out along the maximum diameter of the thrust-sealing surface 21, and the contact of the surface 22 with the seat 12 - along the minimum diameter of the thrust-sealing surface 22.

In the lower part of the small-diameter plunger 6, a discharge valve is installed, including a seat 23, a shut-off element 24, made, for example, in the form of a ball, and a travel stop 25 of the ball 24.

The lower seat 12 of the suction valve and the seat 23 of the delivery valve are installed with the formation of a working cavity 26 between them.

For example, in the shoulder 10 of the plunger 7, at least one through longitudinal groove 27 is made with the possibility of communicating the holes 9 with the working cavity 26.

The plunger 5 is installed in the cylinder 1 to additionally form an upper chamber 28 of variable volume between the sub 4 and 8.

In the lower part of the sub 8 there is a cylindrical recess 29 with a shoulder (not shown in the figure) to form the end surface 30.

The plunger 5 is equipped with a branch pipe 31, the lower part of which is made of a smaller diameter with the formation of a collar (not shown in the figure). The end portions of the branch pipe 31 are made in response to the holes of the sleeve 19 (not shown in the figure) and the cylindrical recess 29 with the possibility of interaction of the shoulder of the branch pipe 31 with the end face of the sleeve 19 and limited axial movement of the sleeve 19 with the pipe 31 between the lower seat 12 and the end surface 30 of the cylindrical recess 29 In the upper part of the branch pipe 31, at least one through radial hole 32 is made, partially covered by the lateral surface of the recess 29 in the upper position of the shut-off element 19.

The nozzle 31 is installed to form a lower annular chamber 33 of variable volume between the plunger 7 and the nozzle 31. The sub 8 has at least one radial hole 34 communicating the upper 28 and lower 33 chambers of variable volume.

The upper plunger 6 is connected, for example, to a drive, by means of a rod string (not shown in the figure).

The delivery valve is installed to communicate the working cavity 26 with the delivery line 35.

The branch pipe 31 (Fig. 4) can be made stepped, with a large diameter in the lower part. In this case, the length of the section 36 of the upper part corresponding to the cylindrical recess 29 must be greater than the total height of the recess and the maximum stroke of the sleeve 19. The outer diameter of the branch pipe 31 can be made slightly less than the diameter of the plunger 7.

The branch pipe 31 can be equipped with at least one additional counterweight 37, made in the form of a ring, fitted on the branch pipe 31.

The plunger 6 (Fig. 5) of small diameter from the bottom can be equipped with a branch 38 connected to the plunger 6, for example, through a sub 8. A discharge valve is installed in the branch 38, which includes a seat 23 and a shut-off element 24. In the lower part of the branch 38, at the inlet into the delivery valve, a cylindrical recess 29 with an end surface 30 is made. The upper part 36 (Figs. 5 and 6) of the branch pipe 31 is made in response to the recess 29.

The pump is assembled as follows.

First, the plunger is assembled with valves. The simultaneous seating of the thrust-sealing surfaces 21 and 22 of the seats 10 and 12 is ensured by adjusting the position of the saddle 12 using the bolt 15. First, the collar 20 sits on the saddle 10, and then the saddle 12 rises up until it touches the thrust-sealing surface 22 when the sleeve 19 is stationary.

The device works as follows.

Let the plunger 1 be in the initial position of lifting the plunger 5 (Figs. 1-3). In this case, the discharge valve is open, the shut-off element 24 is raised above the seat 23, the suction valve is closed. The bushing 19 is in the lowest position with the possibility of interaction of the seats 10 and 12 with the thrust-sealing surfaces of the collar 20 and the lower end of the bushing 19. The pressure in the working cavity 26 is equal to the pressure in the delivery line 35. The pressure in the lower annular chamber 33 of variable volume is greater than the pressure in cavity 26 due to the movement of fluid from the upper chamber 28 of variable volume into the working cavity 26.

When the lower plunger 7 of large diameter moves upward, the volume of the chamber 28 decreases. As a result, the volume of liquid displaced from the chamber 28 through the holes 34, 32, the chamber 33, the working cavity 26 and the discharge valve flows into the pressure line 35. In addition, liquid is supplied to the pressure line from the movement of the plunger 6 of small diameter.

When the plunger 5 approaches the upper position, its speed decreases. This causes the ball 24 to drop onto the seat 23.

In the extreme upper position of the plunger 5, its speed is zero, and the shut-off member 24 is lowered onto the seat 23.

With the reverse stroke of the plunger 5 downward, the volume of the chamber 28 increases, reducing the pressure in it. Under the action of the created pressure drop, the liquid from the lower annular chamber 33 flows into the chamber 28, reducing the pressure in the chamber 33. When the pressure in the chamber 33 becomes less than at the pump inlet, i.e., in the holes 13 and 18 (Fig. 3), the sleeve 19 begins to move upward, breaking away from the seats 10 and 12. When moving upward, the side surface of the recess 29 begins to overlap the radial holes 32, increasing the pressure drop between the working cavity 26 and the chamber 33.

With further downward movement of the lower plunger 7, the sleeve 19 rises completely upward, until the end of the branch pipe 31 interacts with the end surface 30 of the recess 29. In this case, the fluid from the reservoir medium (not shown in the figure) through the axial holes 17 and 13 of the stop 14 and the seat 12, radial holes 9 (Fig. 2) of the plunger 7 enters the working cavity 26.

The force to lift the sleeve 18 upward is determined by the unbalanced cross-sectional area of the sleeve 18, which is proportional to the difference in the squares of the maximum and minimum diameters, respectively, of the thrust-sealing surfaces 21 and 22, as well as the difference in fluid pressure in front of the pump and in the chamber 33.

When the plunger 5 is lowered downwards, the force from the pressure drop on the small diameter plunger 6 acts on it from above.

When the plunger 5 approaches the lowest position, it stops. The movement of liquid through the holes 18, 13, 9 stops. The pressures in the working cavity 26, chambers 33, 28 and in the formation medium are equalized. Under the influence of the weight of the branch pipes 31 and the sleeve 19, the latter is lowered onto the seats 10 and 12.

By varying the thickness of the branch pipe 31, the amount of load on the shut-off element 19 can be adjusted, contributing to its closure. In addition, depending on the viscosity of the formation medium, replaceable nozzles 31 with different weights can be used. At the same time, the dimensions and weight of the shut-off element 19, made of high-strength material, remains constant.

At the beginning of the movement of the plunger 5, hence the lower plunger 7, upward, the pressure in chambers 28 and 33 increases. This leads to an increase in the contact pressure in the mating pairs shoulder 20 - seat 10 and sleeve 19 - seat 12.

Then the cycle is repeated.

When the branch pipe 31 (Fig. 4) is made with a large diameter in the lower part, the load on the closing of the suction valve increases, especially when lifting a high-viscosity liquid. In addition, the total mass of the sleeve 19 and the pipe 31 can be adjusted by equipping the latter with one or more rings 37. At atom, the dimensions of the pipe 31 remain unchanged.

Equipping the plunger 6 (Figs. 5 and 6) from the bottom with a branch 38 with a pressure valve installed in it allows to reduce the harmful volume of the cylinder. As a result, valve opening delays are reduced. The pump works in a similar way.

Thus, the shut-off element 19 of the suction valve and the nozzle 31 move as one piece. This ensures timely closure of the suction valve under the action of the total weight of the sleeve 19 and the nozzle 31. In addition, depending on the viscosity of the formation medium, the mass of the nozzle 31 can be changed by changing its diameter, or by equipping it with counterweights 37. Partial overlap of the radial opening 32 of the nozzle 31 during lifting sleeve 19 allows to reduce the pressure in the upper chamber 28 of variable volume, which ensures the timely opening of the suction valve.

Claims (4)

1. A downhole sucker rod pump containing a cylinder, a suction valve including upper and lower seats, a shut-off element made in the form of a sleeve with an upper shoulder in response to the upper seat, the lower seat is located in the pump bottom with a through axial hole, a plunger with stages of large and small diameter with a discharge valve, the bushing is installed with the possibility of axial movement limited by the stop along the plunger with the formation of a chamber of variable volume formed by the end of the bushing, a plunger stage of small diameter and a cylinder, characterized in that the cylinder is made in steps of large and small diameters in response to the plunger stages, the lower seat is connected to a plunger, in the lower part of which, above the lower seat, at least one through radial hole is made with the possibility of communicating with the axial hole of the bottom, the inlet of the discharge valve is made in the form of a cylindrical recess with an end surface, the plunger is equipped with a branch pipe with a shoulder in the lower part corresponding to the holes bushing and a cylindrical recess with the possibility of interaction of the collar with the end of the bushing, at least one through radial hole is made in the upper part of the branch pipe with the possibility of partially overlapping it with the lateral surface of the cylindrical recess in the upper position of the bushing. 2. The pump according to claim. 1, characterized in that the small-diameter plunger in the lower part is equipped with a central outlet with a discharge valve located therein. 3. The pump according to claim 1 or 2, characterized in that the branch pipe in the lower part is made with a larger diameter, and the length of the upper section is greater than the total height of the cylindrical recess and the maximum stroke of the sleeve. 4. The pump according to claim 1 or 2, characterized in that the branch pipe is equipped with at least one counterweight, made in the form of a ring attached to it.

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