RU2802634C1 - Downhole pumping unit with backwash cleaning - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: downhole pumping unit with backwash cleaning contains a downhole pump, a sand filter with an anchor, consisting of a branch pipe with a packer, a check valve located inside and a sand filter with a container attached from below. Anchor below the outlet, but above the packer, is provided with a plate on the outside for sedimentation of sand from the liquid above. Between the check valve above the packer and the pump inlet, there is a circulation impulse valve, consisting of a cylinder with a coaxial piston with an upper rod pressed by a spring into the upper transport position, which are equipped with a common axial channel for fluid inflow from the well underpacker space to the pump. The stem is equipped with at least one side hole. The cylinder is equipped with a stepped axial cylindrical through hole. The lower cylinder of large diameter is equipped on top with at least one radial hole located above the piston. The upper cylinder is made with the possibility of interacting with the rod, closing the side hole in the transport position and opening the hole when the piston with the rod moves to the lower working position with communication of the side and radial holes. The total cross-sectional area of both the side holes and the radial holes allows to create a pulsed fluid flow with an average speed higher than the rate of settling of destructible mechanical impurities and/or asphalt-hammer-paraffin deposits. The spring force is selected based on holding the piston and rod in the transport position when the lift pipes are filled to the annulus mouth with liquid when the pump is running and providing the necessary frequency of liquid pulsations during backwashing.

EFFECT: increasing the efficiency of backwash by providing a pulsed mode of passage of the flow of process flushing fluid through the downhole pump.

1 cl, 2 dwg

Description

The invention relates to the oil and gas production industry, namely to well pumping units equipped with a packer with backflushing cleaning, which allows cleaning the installation operating in conditions of precipitation of mechanical impurities and/or asphalt, resin, and paraffin deposits (ARPD) provided that the upper operating object is cut off and/or the operational leakage is broken ( casing) column.

The layout of well equipment for artificial lift of oil with mechanical impurities is known (patent RU No. 2782663, IPC E21B 43/08, F04B 47/12, publ. 10.31.2022 Bulletin No. 31), including lowered into the production string, sequentially interconnected strings tubing pipes, a well pump, a receiving filter with a container for collecting mechanical impurities, a check valve, a lower filter, a packer is installed between the filters with the ability to separate the well cavity into a sub-packer and above-packer cavities, characterized in that the upper part of the equipment with a tubing string pipes, a well pump and a receiving filter is disconnected from the lower part, including a connecting and disconnecting device, a packer, a check valve and a lower filter, while the distance between the lower and upper parts is at least 12-15 m, and the lower filter is self-cleaning.

The disadvantages of this equipment are the possibility of emergency situations when removing a packer with an anchor due to the deposition of fine sand fractions that have leaked through an additional sand anchor, picked up by the fluid flow and rising above the packer, a large number of changes in the flow of the produced fluid through perforated pipes before entering the pumping unit, which increases resistance flow and requires the use of more powerful wellhead drives (pumping machines, chain drives, etc.), which leads to increased energy costs, while the flow of fine fractions and paraffin into the pumping unit with the liquid flow is not excluded, and backwashing is a constant flow In this case, technical fluid is of little effectiveness, and it is impossible to use the installation if the integrity of the pipe casing is damaged above the packer installation, which reduces the efficiency of the equipment.

The closest in technical essence is a well pumping unit with an anti-sand filter (patent RU No. 2784705, MPK E21B 43/00, E21B 43/02, publ. November 29, 2022 Bulletin No. 34), including a sucker rod pump running on a pumping string. compressor pipes and having the ability to be driven through a string of sucker rods, and a sand filter with an anchor, consisting of a pipe with a packer located inside a check valve and a sand filter with a container connected below, characterized in that the sand anchor is below the outlet, but above the packer, the outside is equipped with a plate for sedimentation of sand from the liquid flow on top, and the inlet of the well pump is located at a distance from the outlet of the sand filter, ensuring the minimum possible capture of sand with liquid, when the speed of sand deposition is higher than the speed of liquid flow.

The disadvantages of this installation are that fine fractions and paraffin are not excluded from entering the pumping unit with the liquid flow, and backflushing with a constant flow of technical fluid in this case is not very effective, and it is impossible to use the unit if the integrity of the pipe casing is damaged above the packer installation, which reduces the efficiency of the equipment. .

The technical result of the proposed invention is the creation of a well pumping unit that provides expanded functionality due to operation in wells with a violation of the integrity of the casing string above the packer, as well as more effective backflushing due to the use of a pulsed flow mode of the process flushing fluid.

The technical solution is achieved by a downhole pumping unit with backflushing cleaning, including a downhole pump, lowered on a string of lift pipes and capable of being driven from the wellhead, and a sand filter with an anchor, consisting of a branch pipe with a packer, a check valve located inside and a sand filter connected at the bottom. a filter with a container, with the anchor below the outlet but above the packer, equipped with a plate on the outside for sedimenting sand from the liquid on top.

What is new is that to pass liquid from the annulus of the lift pipes inside during backwashing, a circulation pulse valve is located between the check valve above the packer and the pump inlet, consisting of a cylinder with a coaxial piston pressed into the upper transport position by a spring with an upper rod, which are equipped with a common axial channel for the flow of fluid from the sub-packer space of the well to the pump, the rod is equipped with at least one side hole, and the cylinder is equipped with a stepped axial through cylindrical hole, and the lower cylinder of large diameter is equipped on top with at least one radial hole located above the piston, and the upper cylinder is designed to interact with a rod, closing the side hole in the transport position and opening the hole when moving the piston with the rod to the lower working position with communication between the side and radial holes, the total cross-sectional area of both the side holes and radial holes allows you to create a pulsed fluid flow with an average speed higher than the speed deposition of destructible mechanical impurities and/or asphalt-and-paraffin deposits, while the spring force is selected based on holding the piston and rod in the transport position when the annulus of the elevator pipes is filled to the mouth with liquid while the pump is running and ensuring the required frequency of liquid pulsations during backwashing.

In fig. Figure 1 shows a diagram of a well pumping unit with a liner in a longitudinal section.

In fig. Figure 2 shows a pulse circulation valve in a longitudinal section.

The downhole pumping unit (Fig. 1) with backflushing cleaning includes a downhole pump 1 (shown conditionally), lowered into the well 2 on a string of lift pipes 3 and capable of being driven from the mouth (not shown) of the well 2, and a sand filter 4 with anchor 5, consisting of a pipe 6 with a packer 7, a check valve 8 located inside and a sand filter 4 with a container 9 attached from below, and the anchor 5 is below the outlet 10, but above the packer 7, and is externally equipped with a plate 11 for sedimenting sand from the liquid on top. Well pump 1 can be made in the form of a deep-rod pump (SRP), the plunger (not shown) of which is driven by a wellhead drive (pumping machine, chain drive, etc. - not shown) using rods (not shown), gerotor pump), the rotor (not shown) of which is driven by a wellhead drive (electric motor, gearbox, etc. - not shown) using rods (not shown), an electric centrifugal pump (ESP), the rotor (not shown) of which is driven a submersible electric motor (not shown) using electricity supplied from the wellhead via a cable (not shown), or any other deep pump that passes liquids from the bottom up after stopping operation. To pass liquid from the annulus of lift pipes 3 inside during backwashing, a circulation pulse valve 13 is located between the check valve 8 above the packer 7 and the inlet of the pump 12. The valve 13 (Fig. 2) consists of a cylinder 14 with a coaxial piston pressed by a spring 15 into the upper transport position 16 with an upper rod 17, which are equipped with a common axial channel 18 for the inflow of formation fluid 19 (Fig. 1) from the sub-packer space 20 of the well 2 to the well pump 1. The rod 17 (Fig. 2) is equipped with at least one side hole 21, and the cylinder a stepped axial through cylindrical hole 22. The lower cylinder 23 of the large diameter hole 22 (D1) is equipped on top with at least one radial hole 24 located above the piston 16, and the upper cylinder 25 (with an internal diameter of D2) is designed to interact with the rod 17, closing the side hole 21 in the transport position and opening the hole 21 when moving the piston 16 with the rod 17 to the lower working position with communication between the side 21 and radial 24 holes. The total cross-sectional area of both the side holes 21 and the radial holes 24 makes it possible to create a pulsed flow of liquid with an average speed higher than the deposition rate of destructible mechanical impurities and/or paraffin. The rate of deposition of at least 85% of the heaviest and most dangerous for well pump 1 (Fig. 1) mechanical impurities and/or paraffin is determined in laboratory conditions by taking samples of well fluid raised by pump 1 to the surface. The average speed of liquid flow through the circulation valve 13 and pump 1 is determined by pumping liquid through them in laboratory conditions, supplying liquid into the radial holes 24 and measuring the volume of passing liquid per unit of time (usually m ³ /min, converted by dividing by 60, in m ³ /s). When the flow rate is lower than the deposition rate of impurities and/or paraffin, the size and/or number of lateral 21 (Fig. 2) and radial 24 holes, which increases their cross-sectional area, reduces the resistance to fluid flow and, as a consequence, increases the pumped fluid flow rate through them, until an average flow rate is obtained that is higher than the rate of deposition of impurities and paraffin. By pumping liquid with different pulsation frequencies through pump 1 (Fig. 1), the required frequency (ν) is determined at which mechanical impurities and paraffin particles inside pump 1 are most effectively destroyed.

The minimum force of the spring 15 (Fig. 2) is selected based on holding the piston 16 and rod 17 in the transport position when the annulus of the elevator pipes 3 is filled to the mouth of the well 2 (Fig. 1) with liquid while the pump 1 is running, reducing the pressure inside the circulation valve 13. For ensuring the required pulsation frequency of the liquid during backwashing is selected in laboratory conditions by adjusting the stiffness (stiffness coefficient k, N/m) of spring 15 (Fig. 2), which provides the required pulsation frequency, since the oscillation frequency of the spring pendulum is equal (without taking into account friction forces) :

where ν – pulsation frequency, 1/s;

π≈3.14;

k – stiffness coefficient, N/m;

m – mass of moving parts (piston 16 with rod 17), kg.

Since during adjustment it is impossible to change the mass of the piston 16 with the rod 17, the adjustment is carried out by selecting the stiffness (stiffness coefficient k, N/m) of the spring 15. The greater the stiffness of the spring 15, the higher the pulsation frequency. It is possible to directly select springs 15 with different stiffnesses or use adjusting attachments 26 or adjusting nuts (not shown) - the authors do not claim this.

Structural elements, technological connections and seals that do not affect the performance of the well pumping unit are not shown in the drawings (Figs. 1 and 2) or are shown conditionally.

A downhole pumping system with backflushing treatment works as follows.

The circulation valve 13 (Fig. 2) with a piston 16 inserted into the axial hole 22 of the cylinder 14 with a rod 17, which is pressed upward with a spring 15 adjusted for rigidity (for example, a washer 26), is connected to the inlet 12 (Fig. 1) of the well pump 1 In well 2, a packer 7 with a sand filter 4, an anchor 5, consisting of a branch pipe 6 with a check valve 8, and a container 9, is lowered into well 2 and installed above the formation 19 and below the violation (if any) of the leakage of the casing string (shown conditionally) of well 2, and the anchor 5 is below the outlet 10, but above the packer 7, and is equipped with a plate 11 on the outside. In this case, the outlet 10 of the anchor 5 is equipped with a locking support (not shown) of any known design (the authors do not claim this). From below, the circulation valve 13 is equipped with a nipple (not shown) of any known design (the authors do not claim this) under the corresponding locking support of the anchor 5, after which the pump 1 with the circulation valve 13 is lowered into the well until the locking support of the anchor 5 and the nipple of the circulation valve 13 are hermetically sealed. The wellhead 2 is isolated with wellhead fittings (not shown), the well pump 1 is connected using rods or a cable, respectively, to the wellhead drive or control and power unit and put into operation. At the inlet 12 of the well pump 1, during operation, a vacuum is created, where the production of the formation 19 comes from the sub-packer space 20, passing through a sand filter 4, which does not allow coarse sand (more than 0.5 mm) inside, which is deposited on the sump (not shown) of the well 2 , pipe 6, check valve 8, cylinder 14 (Fig. 2) of the circulation valve 13, common axial channel 18 of the piston 16 and rod 17. Moreover, the production of the formation in the filter 4 first drops down to the lower edge of the pipe 6, where it sharply changes direction to the bottom c upward, while mechanical impurities and sand that have leaked into filter 4, by inertia due to the relatively large mass, settle and collect in container 9, and a fine suspension of sand and mechanical impurities with paraffin (the sedimentation rate of which is less than the speed of liquid flow in filter 4) rises with the fluid flow and is deposited in the well pump 1. The production of the formation 19 by the pump 1 along the string of lift pipes 3 rises to the surface, where it is collected and sent for processing (the authors do not claim this).

Also, when the well pump is running, a vacuum (pressure P1) is created inside the cylinder 14 (Fig. 2) of the circulation valve 13, creating a pressure difference (ΔP) with the pressure (P2) outside the cylinder 14 (in the annulus of the lift pipe string 3 - Fig. 1). In this case, a downward force acts on the piston 16 (Fig. 2):

where F is the force acting on the piston, N;

D1 – diameter of the lower cylinder 23 of the common hole 22, m;

D2 – diameter of the upper cylinder 25 of the common hole 22, m;

ΔP – pressure difference outside (P2) and inside (P1) cylinder 14, N/m ² .

In this case, the pressure drop (ΔP) is determined by the formula:

where ΔP is the pressure difference outside (P2) and inside (P1) cylinder 14, N/m ² ;

P2 – pressure outside the cylinder 14, N/ ^m2 ;

P1 – pressure inside the cylinder 14, N/m ² .

The pressure inside the cylinder 14 is determined by the operating characteristics of the well pump 1 (Fig. 1), and the pressure outside the cylinder 14 (Fig. 2) during operation of the well pump 1 (Fig. 1) by the liquid level in the annular annulus of the tubing string 3:

where P2 is the pressure outside the cylinder 14, N/ ^m2 ;

ρ – liquid density in the annulus of the elevator pipe column 3 (Fig. 1), kg/m ³ ;

g – gravitational acceleration ≈ 9.81, m/s ² ;

h – vertical distance from the liquid level (not shown) in the annulus of the elevator pipe column 3 to the radial holes 24, m.

Despite the force (F) acting on the piston 16 (Fig. 2), the force created by the spring 15 does not allow the side holes 21 of the rod 17 to exit the upper cylinder 25 of the cylinder 14 and open, excluding the communication of the input 12 (Fig. 1) well pump 1 with the annulus of the lift pipe string 3, which is especially important if there are disturbances in the casing of well 2 above packer 7.

Over time, mechanical impurities and paraffin deposits (plaque) are deposited on the structural elements (not shown) of the well pump 1, which interacts with the production of formation 19 when pumping to the surface, increasing the friction force and, as a consequence, the effort to move the moving parts (not shown) well pump 1, reducing the coefficient of efficiency (efficiency), and during long-term operation without cleaning the well pump 1 can lead to emergency situations, that is, jamming (impossibility of moving) of moving parts. To clean the structural elements of the well pump 1, the annulus of the lift pipe column 3 is filled with process flushing liquid (process water, water with soda, water with surfactants, water with hydrocarbon solvents, etc.), which the technologists select for the most effective dissolving plaque on the structural elements of the well pump 1. Then, in the annular column of the lift pipes 3, a wellhead pump (not shown) creates excess pressure sufficient to open the circulation valve 13, in which a pressure difference (ΔP) is applied, determined by the formula [2]. However, the pressure inside the cylinder 14 (Fig. 2) is determined by the formula

where P1 is the pressure inside the cylinder 14, N/m ² ;

ρ is the density of the liquid in the column of elevator pipes 3 (Fig. 1), kg/ ^m3 ;

g – gravitational acceleration ≈ 9.81, m/s ² ;

H – vertical distance from the wellhead 2 in the string of elevator pipes 3 to the radial holes 24, m.

The pressure outside the cylinder 14 (Fig. 2) is determined by the formula:

where P2 is the pressure outside the cylinder 14, N/ ^m2 ;

ρ – liquid density in the annulus of the elevator pipe column 3 (Fig. 1), kg/m ³ ;

g – gravitational acceleration ≈ 9.81, m/s ² ;

N – vertical distance from the wellhead 2 in the annular column of the lift pipes 3 to the radial holes 24 (Fig. 1), m;

p – pressure created by the wellhead pump, N/m ² .

The pressure difference (ΔP) creates a force (F), determined by the formula [1], under the action of which the spring 15 (Fig. 2) compresses the side hole 21 of the rod 17 and exits the upper cylinder 25 into the lower cylinder 23, communicating with the radial holes 24. Liquid from the annulus of the lift pipe string 3 (Fig. 1) through radial holes 24 (Fig. 2) and side holes 21 enters the well pump 1 (Fig. 1) and along the lift pipe string 3 to the surface, performing backwashing. In this case, the pressures inside and outside the cylinder 14 (Fig. 2) at the level of the radial hole 24 are approximately equalized, and the spring 15 moves the piston 16 with the rod 17 upward until the side holes 21 are blocked by the upper cylinder 25. The fluid flow is stopped by the pressure difference inside and outside the cylinder 14 increases sharply, the spring 15 (Fig. 2) compresses the side hole 21 of the rod 17 comes out of the upper cylinder 25 into the lower cylinder 23, communicating with the radial holes 24, passing the next portion of liquid from the annulus of the elevator pipe column 3 (Fig. 1) through the radial holes 24 (Fig. 2) and side holes 21 in the well pump 1 (Fig. 1). Next, the cycle of opening and closing the side holes 21 (Fig. 2) is repeated, providing a pulsed supply of liquid (in portions with a certain frequency - ν) to the well pump 1. As practice has shown, the use of a pulse mode correctly selected in terms of frequency (ν) is 1.5 – Reduces the cleaning time of well pump 1 by 2 times compared to constant flushing.

Upon completion of flushing of the well pump 1 (determined by the absence of removal of mechanical impurities and paraffin from the lift pipe string 3), the pumping of liquid into the annulus of the lift pipe string 3 by the wellhead pump is stopped, the spring 15 (Fig. 2) moves the piston 16 with the rod 17 upward until the side holes 21 by the upper cylinder 25, and the well pump 1 (Fig. 1) is put into operation in normal mode to raise the production of the formation 19 to the surface.

Mechanical impurities deposited from the liquid in the annulus of the lift pipe column 3 are retained by the plate 11, preventing them from clogging the moving parts (not shown) of the packer 7, which makes it easier to remove the packer 7 if necessary and eliminates emergency situations.

The proposed downhole pumping unit makes it possible to expand its functionality by working in wells with a violation of the integrity of the casing string above the packer, as well as to carry out more efficient backflushing through the use of a pulse mode for the flow of technological flushing fluid through the downhole pump.

Claims (1)

Downhole pumping installation with backflushing cleaning, including a downhole pump, lowered on a string of lift pipes and capable of being driven from the wellhead, and a sand filter with an anchor, consisting of a branch pipe with a packer located inside a check valve and a sand filter with a container attached at the bottom , wherein the anchor below the outlet, but above the packer, is externally equipped with a plate for depositing sand from the liquid on top, characterized in that to pass liquid from the annulus of the lift pipes inside during backwashing, a circulation pulse valve consisting of a cylinder is located between the check valve above the packer and the pump inlet with a coaxial piston with an upper rod pressed by a spring into the upper transport position, which are equipped with a common axial channel for the flow of liquid from the under-packer space of the well to the pump, the rod is equipped with at least one side hole, and the cylinder is equipped with a stepped axial through cylindrical hole, and the lower cylinder of large diameter is equipped with on top with at least one radial hole located above the piston, and the upper cylinder is configured to interact with the rod, block the side hole in the transport position and open the hole when moving the piston with the rod to the lower working position with communication of the side and radial holes, total cross-sectional area both side holes and radial holes allows you to create a pulsed flow of liquid with an average speed higher than the deposition rate of destructible mechanical impurities and/or asphalt, resin, and paraffin deposits, while the spring force is selected based on holding the piston and rod in the transport position when the lift pipes are filled to the mouth with annular fluid when the pump is running and ensure the required frequency of liquid pulsations during backwashing.