RU2743115C1 - Well sucker-rod pump with vertical spring pressure oscillation compensator - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention relates to production of oil, in particular, to installations of borehole sucker-rod pumps. Disclosed is a downhole sucker-rod pump unit comprising a pump, pump string and a string, a vertical spring compensator mounted on the injection line by means of an outlet and a flange connection. At that, the spring compensator includes a housing with a cast piston located inside, the inner surface of which is made in the form of two hemispheres, having two holes located at an angle to the liquid flow, with perpendicular location of axes and intersection in center of piston reciprocating under action of liquid, and working section including bushings and three compression springs with vertical arrangement for uniform distribution of longitudinal load.

EFFECT: technical result consists in providing a high degree of alignment of non-uniformity of supply of well sucker-rod pump unit in wide ranges by selecting parameters and series connection of springs without using gas compression work of specified volume, in increase of working elements durability.

1 cl, 2 dwg

Description

The invention relates to the field of oil production, in particular to installations of downhole sucker rod pumps.

Known downhole sucker rod pumping unit with a pneumatic compensator installed at the wellhead and communicated with the flow line by means of a branch. According to the invention, the pneumatic compensator consists of two parts: the lower part is a cylinder-shaped part and the upper part is a hemisphere, which are fastened together with pins. An insert is installed in the lower part of the working chamber. It is communicated with the flow line by means of a branch (RU 164585, 09/10/2016).

The disadvantages of this technical solution are the increased metal consumption of the structure, due to the installation of liners in the pneumatic compensator housing, as well as increased wear of the diaphragm at low temperatures, which reduces the performance of the pneumatic compensator.

The closest in principle of operation is a downhole sucker-rod pumping unit with a pneumatic compensator, consisting of two hemispheres, which are fastened together with studs (Patent RU 2655485, 05/28/2018). The pneumatic compensator is installed in a sealed chamber, insulated from the environment, inside which a well is drilled with a depth exceeding the depth of freezing of the soil, and the well is closed with a metal mesh, and the chamber body has a hinged cover, the working cavity of the pneumatic compensator is connected to the annular space of the well through a spring safety valve.

The disadvantages of this technical solution are the complexity of installing a heat-insulating chamber, additional costs for its maintenance to ensure the isolation of the pneumatic compensator from the effects of low temperatures, large dimensions, low durability of the diaphragm, susceptibility to corrosive wear of parts in contact with the liquid, as well as the inability of the pneumatic compensator to effectively extinguish pressure pulsations.

The objectives of the invention are to reduce the pressure pulsation in a wide range at the outlet from the pumping unit, as well as to increase the durability of the working element and the housing of the pressure fluctuation compensator, to reduce maintenance costs, to reduce the overall dimensions, due to the installation of vertical steel springs and an O-ring in the housing. preventing contact of liquid with the housing of the compensator for pressure fluctuations.

These tasks are solved by the fact that a downhole sucker rod pumping unit containing a pump, strings of pumping pipes and rods is equipped with a vertical spring compensator consisting of a housing with a cast piston located inside, the inner surface of which is made in the form of two hemispheres containing two holes located under a certain angle to the fluid flow, with a perpendicular arrangement of the axes and intersection in the center of the piston, which reciprocates under the action of the fluid along the sealing ring, the working section, including bushings and compression springs, parameters (stiffness, length, diameter, number of turns, etc.) which are selected in such a way that damping of pressure pulsations occurs in wide ranges, and the load on the turns is evenly distributed.

The housing cover, fixed with pins to the working section and containing a transport eyelet, serves for a tight connection. The bottom flange is designed in such a way that its shape facilitates smooth and efficient fluid supply to the piston bores for co-direction. An O-ring installed in the body and fixed with a seat disc prevents corrosive wear of the inner walls of the compensator body.

FIG. 1 shows the device of a vertical spring compensator.

Vertical spring expansion joint design:

1 - case;

2 - working section;

3 - hairpins;

4 - piston;

5 - through holes;

6 - stock;

7 - bushings;

8, 9, 10 - springs;

11 - housing cover;

12 - transport eyelet;

13 - flange;

14 - fastening element;

15 - gasket;

16 - landing disk;

17 - rod seals;

18 - end seals;

19 - a sealing ring.

FIG. 2 schematically shows a general view of a downhole sucker rod pumping unit with a vertical spring compensator. Downhole sucker rod pumping unit design:

20 - machine - rocking chair;

21 - wellhead equipment;

22 - a string of pumping pipes;

23 - discharge line;

24 - support;

25 - branch;

26 - vertical spring compensator.

The vertical spring compensator (Fig. 1) consists of two sections - the lower one, represented by the body 1, and the upper one - in the form of a working section 2. The connection of the two sections is carried out by tightening the studs 3. Inside the lower section, there is a working body - a piston 4, which serves for the formation of counter streams for their subsequent swirling and collision to ensure partial damping of pressure pulsations.

The piston 4 and the rod 6 containing the mounting slots are made by casting. Bushings 7, worn along the rod 6, serve to install and fix springs 8, 9, 10 - low, medium, high rigidity, respectively, as well as to transmit the translational motion from the piston 4. The housing cover 11 with grooves for the spring 10, containing the transport eye 12 for transportation and repair, as well as a hollow section for free movement of the rod 6, is installed at the top of the working section 2 and is fixed with pins 3.

A flange 13 is attached to the lower part of the housing 1 by means of fasteners 14. The flange 13, which is attached to the counter flange from the side of the discharge pipeline, contains grooves for installing a gasket 15 to reduce shock loads from the side of the piston 4, as well as internal walls located at a certain angle for efficient supply of liquid along the inner walls of the piston 4 into the holes 5. The landing disk 16 is installed in the grooves of the body and has recesses for seating the rod seals 17 along the outer walls of the rod 6. End seals 18 are installed at the joints of the body parts 18. O-ring 19 pressed by the flange 13 and is fixed by a seating disc 16 to prevent bends, is installed in the housing 1 and serves to seal and prevent corrosive wear of the compensator housing under the influence of an aggressive environment.

The device works as follows.

The downhole sucker rod pumping unit supplies liquid to the injection line 23 with the vertical spring compensator 26 installed on it by means of an outlet 25 and a flange connection. In this case, the pump piston moves with some deceleration and acceleration, causing pressure pulsation. The liquid bends around the walls of the flange 13 and enters the hemispherical cavity of the piston 4, then moves into the holes 5 and mixes with the counter flow from the opposite side. Two counter streams form vortices due to the angular arrangement of the holes 5, thereby absorbing some of the energy of the flow pulsation.

Under the action of the pressure of the liquid pumped by the pumping unit, the piston 4, located in the housing 1, drives the rod 6, which moves in translational motion together with the bushings 7, actuating the springs 8, 9, 10, located in the housing 1 and the working section 2 ...

In the springs, elastic forces arise, directed in the opposite direction to the forces on the piston 4 under the action of the liquid. When fluid is pumped, the springs 8, 9, 10 are compressed, experiencing cyclic loads. Due to the compression forces of the springs 8, 9, 10, the pump delivery is equalized, ensuring the efficient operation of the pumping unit as a whole.

Compression springs 8, 9, 10 are installed in the grooves of the expansion joint structure elements, the parameters (stiffness, length, diameter, number of turns, etc.) of the springs are selected in such a way that damping of pressure pulsations is provided in wide ranges, and the load on the turns of each individual spring occurs consistently and evenly, increasing their durability and working efficiency. Spring 8 is designed for low pressure fluctuations, spring 9 - for medium, spring 10 - for high. Spring 8 has a smaller cross-sectional area of the coils compared to springs 9, 10, but a large number of coils and a stroke length. Such a design of the spring 8 is necessary in order to compensate for the load from the weight of the piston 4, the rod 6 and the bushings 7 when pumping liquid.

With a steady-state amplitude of pressure fluctuations at the outlet of the pumping unit, all of the listed springs are involved in the work, which makes it possible to evenly distribute the load. In particular, in case of pressure drops, collision of the coils with subsequent deformation is excluded due to the effective sequential transmission of compression to each spring. The design of this type allows the expansion joint to be used in wide ranges of pressure fluctuations, as well as to increase the durability of the working elements - springs, due to the uniform distribution of the longitudinal load.

The stem stroke limiting device is absent due to the selection of the stiffness of the spring 10, such that the maximum pressure developed by the pump does not exceed the spring force.

The piston 4 is installed in the cavity of the housing 1 and, during movement, touches the walls of the sealing ring 19. The landing disc 16 is designed in such a way that excludes the bends of the sealing ring 19 to ensure the free stroke of the piston 4. The impact of the piston 4 on the landing disc 16 is also excluded due to the selection of the parameters of the spring 10 at which the maximum pressure developed by the pump does not exceed the spring force.

The given design of the vertical spring compensator provides a high degree of equalization of the unevenness of the flow of the downhole sucker rod pumping unit in wide ranges, due to the selection of parameters and the series connection of springs without using the work of gas compression of a given volume, has a high durability of working elements, as well as low weight, small overall dimensions and low metal consumption, which increases economic efficiency in the production, transportation and repair of the expansion joint.

Claims (1)

Downhole sucker rod pumping unit containing a pump, strings of pumping pipes and rods, a vertical spring compensator installed on the discharge line using a branch and a flange connection, characterized in that the spring compensator is equipped with a cast piston located inside the body, the inner surface of which is made in the form of two hemispheres containing two holes located at an angle to the fluid flow, with a perpendicular arrangement of the axes and the intersection in the center of the piston, which reciprocates under the action of the fluid, by a working section, including bushings and three compression springs with a vertical arrangement for uniform distribution of the longitudinal load, which are compressed at low, medium and high pressure fluctuations, respectively.

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