RU2822337C1 - Electrical submersible pump unit - Google Patents

Abstract

FIELD: oil industry.

SUBSTANCE: invention relates to the oil industry, namely to oil production using electrical submersible pumps (ESP unit) for oil production from wells in conditions of high gas factor. Electric centrifugal pump unit includes an electric motor with hydraulic protection and an inlet module arranged inside the casing, pump sections, a tubing string with whipped and check valves, a cable. Lower part of the casing is connected in series to the bypass valve and the inner pipe connected to the adapter coupling, at the same time adapter coupling is made with radial holes and with two internal threaded outputs, in which upper and lower external pipes are installed, upper outer pipe faces the wellhead with its open part, and the lower one is plugged. Thus, the proposed unit increases reliability of ESP unit operation at oil production in conditions of high gas factor due to gas separation before liquid enters the ESP and increase of flow rate of formation fluid washing over the electric motor.

EFFECT: increased reliability of ESP unit operation at oil production in conditions of high gas factor due to gas separation before liquid supply to ESP and increase of flow rate of formation fluid washing with electric motor.

1 cl, 2 dwg

Description

The invention relates to the oil production industry, namely to oil production using electric submersible pumps (ESP) for oil production from wells under conditions of high gas factor.

The operation of production wells using ESPs is one of the main methods of mechanized oil production both in the Russian Federation and abroad. In connection with the ongoing measures to optimize extraction and reduce bottomhole pressure when operating wells using ESPs, one of the problems is the high gas content at the inlet, which leads to unstable operation of the ESP, a decrease in its service life, and emergency shutdowns.

One of the common ways to increase the reliability of ESP operation is to equip the ESP with a casing to increase the cooling of the electric motor by increasing the flow rate of the formation fluid washing the electric motor. The housing for the casing is made in the form of a pipe, with the possibility of placing an input module and an electric motor with a protector inside it in such a way as to ensure the movement of formation fluid flow through the gap between the housing and the electric motor. The use of a casing turns out to be insufficiently effective at low bottomhole pressure and a high gas factor, since free gas accumulating inside the casing also leads to unstable operation of the ESP, supply interruptions, and reduced reliability.

A downhole pumping unit is known (patent RU No. 2586349, MPK E21B 43/00, E21B 43/38, published on June 10, 2016 in Bulletin No. 16), including a rod pump, a liner pipe with a check valve, installed on a packer, and that the commutator, mounted on the stops of the liner pipe, hydraulically connects the said liner pipe through a check valve installed at its upper end with a candle pipe, the length of which exceeds the distance from the dynamic level to the depth of the pump suspension, while the liner pipe with the pipe - the candle forms a hydraulic channel for communication between the well bottom and the annulus; parallel to the pipe-candle, a rod pump is installed on the upper half of the coupling of the mentioned commutator, while the lower end of the commutator is made in the form of a truncated cone with the base directed downwards, and is equipped with centralizers along the outer diameter.

The disadvantages of this installation are low productivity due to the use of a rod pump, high accident rate due to the use of a packer, which can lead to complications both during installation and when the packer fails. The use of a spark plug pipe for an ESP is not applicable due to the dimensions of the ESP and motor; in addition, it will lead to failure of the submersible electric motor (SEM) due to overheating as a result of liquid entering the pump intake, bypassing the SEM.

An electric centrifugal pumping installation is known (patent RU No. 2737805, IPC E21B 43/38, published on December 3, 2020 in Bulletin No. 34), including wellhead equipment, a control panel, a tubing string installed on the string in the well sequentially from bottom to top, electric centrifugal pump - an ESP, equipped with pressure sensors, a cable, a parallel anchor, on which a pipe bell, a helicoidal pipe, a pipe, a packer are fixed in parallel from top to bottom, with the ESP inlet located above the packer, and the outlet of the nozzle is located above the pump inlet, and the input is communicated with the sub-packer space of the well, the selection of degassed formation products by a pump along the tubing string, and gas - from the annulus.

The disadvantage of this installation is the rapid failure of the ESP due to insufficient cooling of the electric motor, since the supply of liquid to the ESP intake occurs through a pipe, the outlet of which is located above the ESP and the motor.

The closest in design is the installation of an electric centrifugal pump (patent RU No. 2773996, IPC F04D 13/10, published on June 14, 2022 in Bulletin No. 17) including an electric centrifugal pump with a submersible electric motor in a sealed casing, a power cable with a cable entry. The electric centrifugal pump is located above a sealed casing with a submersible electric motor; the sealed casing with its upper part covers the receiving part with the inlet module of the electric centrifugal pump; the input module is additionally equipped with a cable cuff that fits tightly to the module, sealing the cores of the installation’s power cable; the input module is fastened to the cable cuff by a sealing ring covering them, covering the annular gap between the inner surface of the casing and the input module with the attached cable cuff.

The disadvantage of the installation is low efficiency at a high gas factor, since free gas accumulating inside the casing leads to unstable operation of the ESP, supply interruptions, and reduced reliability.

The technical result of the invention is to increase the reliability of ESP operation during oil production under conditions of high gas factor due to gas separation before liquid enters the ESP and increasing the flow rate of formation fluid washing the electric motor.

The technical result is achieved by installing an electric centrifugal pump, including an electric motor with hydraulic protection and an inlet module located inside the casing, pumping sections, a string of tubing and compressor pipes with knock-down and check valves, and a cable.

What is new is that the lower part of the casing through a sub is connected in series with the bypass valve and the inner pipe connected to the transfer coupling, while the transfer coupling is made with radial holes and with two internal threaded leads into which the upper and lower outer pipes are installed, the upper outer the pipe faces the open part towards the wellhead, and the lower one is plugged.

Figure 1 shows a diagram of the proposed installation, Fig. Figure 2 shows a cross-section of a transfer coupling with radial holes, where the electric motor is 1, the hydraulic protection is 2, the inlet module is 3, the casing is 4, the ESP pumping sections are 5, the tubing string is 6, the check valve is 7, the knock-down valve is 8, the cable is 9, sub - 10, bypass valve - 11, inner pipe - 12, transfer sleeve - 13, radial holes - 14, upper outer pipe - 15, lower outer pipe - 16, plug - 17.

The installation of an electric centrifugal pump consists of an electric motor 1 with hydraulic protection 2 and an inlet module 3 located inside a casing 4, pumping sections of an ESP 5, a tubing string 6 with a knock-down valve 8 and a check valve 7, cable 9.

The lower part of the casing 4, through a sub 10, is connected in series with the bypass valve 11 and the inner pipe 12, connected to the transfer coupling 13.

In this case, the transfer coupling 13 is made with radial holes 14 and with two internal threaded leads (not shown in Fig. 1,2), into which the upper 15 and lower 16 outer pipes are installed.

The upper outer pipe 15 faces the open part towards the wellhead (not shown in Fig. 1, 2), and the lower one 16 is plugged.

The proposed setup works as follows.

During operation of the ESP, gas, due to a change in the direction of liquid flow in the area of the open part of the upper outer pipe 15, is separated from the liquid and enters the annulus, and the liquid through the radial holes 14 of the transfer coupling 13 into the lower outer pipe 16, where due to a change in the direction of flow liquid, large mechanical impurities are deposited above the plug 17. Next, the liquid through the inner pipe 12 and casing 4 enters through the inlet module 3 into the pumping sections of the ESP 5 and then rises along the tubing string 6 to the wellhead.

Bypass valve 11, opening at a pressure drop of 0.3 MPa, is designed to eliminate the risk of supply failure in the event of clogging of the radial holes 14 with mechanical impurities or deposits.

Thus, the proposed installation increases the reliability of ESP operation during oil production under conditions of high gas factor due to gas separation before liquid enters the ESP and increasing the flow rate of formation fluid washing the electric motor.

Claims (1)

Installation of an electric centrifugal pump, including an electric motor with hydraulic protection and an inlet module located inside the casing, pumping sections, a tubing string with a knock-down and check valve, a cable, characterized in that the lower part of the casing through a sub is connected in series with the bypass valve and the inner pipe connected to the transfer coupling, while the transfer coupling is made with radial holes and with two internal threaded leads into which the upper and lower outer pipes are installed, the upper outer pipe faces the open part towards the wellhead, and the lower one is plugged.