RU119020U1 - CORROSION SUBMERSIBLE PUMP UNIT PROTECTION DEVICE - Google Patents

Abstract

A device for protecting a submersible pumping unit from corrosion, consisting of a threaded nipple screwed with a submersible electric motor, insulators and an electrode, characterized in that it additionally contains a body, a semiconductor diode, the anode of which is connected to the body of the device, and the cathode to an electrode made of corrosion-resistant steel, concentrically located inside the casing with the help of insulators, in the lower part of the electrode there is a drainer assembly, consisting of a set of wire brush discs, the material of which is corrosion-resistant, high-alloy twisted steel, the outer diameter of the discs corresponds to the inner diameter of the casing, providing guaranteed galvanic metal contact with a casing string.

Description

The utility model relates to the oil industry, in particular, to oil production from wells in complicated geological and technical conditions.

Known borehole pump, which is a vertical single-acting design with a fixed cylinder, a movable metal plunger and ball valves; lowered into the well on a string of tubing and sucker rods (1). Oilfield Equipment: Handbook / Ed. EI Bukhalenko 2nd ed., Revised and supplemented by M .: Nedra, 1990. - 559 pp., Ill. - analogue.

The disadvantage of a downhole pump is its applicability only in low-production wells and the need to use complex metal-intensive ground equipment (rocking machine), as well as its limited applicability with a large gas factor and a large curvature of the wells, typical for cluster drilling and significant wear due to significant corrosion in watered wells with significant salinity.

Also, a well-known technical solution is the installation of a submersible centrifugal pump, which includes a submersible electric pump unit, which combines an electric motor with hydraulic protection, a pump and a cable line, lowered into the well by lifting tubing; mouth equipment; a control station and a transformer, in the lower part of the installation there is an electrode isolated from the housing, electrically connected to a common point of the motor windings connected to a "star" through a diode assembly, and its "positive" terminal is connected to the electrode. The design allows to obtain a potential difference on the electrode relative to the tubing string due to overflows in the three-phase windings of the electric motor during pump operation and to provide cathodic protection of metal equipment from corrosion and prevention of accumulation of solid deposits on the protected equipment (RF Patent No. 2217579) (2).

The disadvantage of this device is the complexity of the transition device and the need to change the design of the PED.

The closest technical solution adopted for the prototype is a corrosion protection device for a submersible pump installation consisting of an electric submersible pump unit that combines an electric motor with hydraulic protection, a pump and a cable line that are lowered into the well by lifting tubing; mouth equipment; a control station and a transformer isolated from the casing, an electrode made of having a higher negative electrochemical potential with respect to the casing and the installation casing and insulating elements, characterized in that grooves are made in the insulating elements on the sealing surfaces in which the sealing rings are located (Utility Patent Model No. 80190), (3).

However, in most of the studied wells, there is a non-zero electric potential, changing with a frequency of 50 Hz. The range of potential change at different wells ranged from 0.06 to 28 V. The shape of the curve is close to sinusoidal. The constant component of the electric potential is absent (II = 0). In particular, the potential on the cable armor is possible due to a violation of the tightness of the cable insulation. In this case, the strength of the anode fracture current can reach several tens of amperes. In addition, the rate of destruction of the metal is higher, the higher the flow rate of the lift fluid, despite the absence of a constant component. When the flow rate of the lift fluid (electrolyte) is 12 m / s, the rate of destruction of the test metal is three times higher than the rate of destruction in the standing fluid. Under actual operating conditions of wells, the current strength between the PEM body and the casing can reach amperes, at a fluid flow rate of several tens of meters per second, which further reduces the operating time of the PEM and the pump unit as a whole. Thus, when powered by transformer control stations, a significant electric potential of industrial frequency is induced on the surface of the SEM housings and other elements of downhole equipment. In turn, high-performance ESPs are equipped with high-power PEDs, which are characterized by high voltages and currents in the cable line, which leads to higher values of the electric potential induced on the surface of the PED, while the high-performance ESPs provide an increased rate of lift fluid flow in the gap between the PEM and the casing, which further accelerates the electrolytic destruction of the metal, dramatically reducing the time between failures.

The purpose of the utility model is to prevent corrosion damage to downhole equipment caused by the presence of stray currents, phase imbalance, leakage currents in the cable, and the appearance of static charges on the housing elements of the pumping equipment during production.

This goal is achieved in that the device for protecting the submersible pump installation from corrosion, consists of a threaded nipple screwed with a submersible electric motor, insulators and an electrode, further comprises a housing, a semiconductor diode, the anode of which is connected to the housing of the device, and the cathode to the electrode made of steel concentrated inside the housing with the help of insulators, in the lower part of the electrode there is a stacker assembly consisting of a package of wire brush disks with material which is A corrosion resistant, high alloy twisted steel is used, the outer diameter of which corresponds to the inner diameter of the casing, providing guaranteed galvanic (metal) contact with the casing.

In FIG. The claimed device is schematically depicted.

The corrosion protection device of a submersible pump installation consists of a threaded nipple screwed onto a SEM (submersible electric motor) pos. 1, a housing pos. 2, insulators pos. 3, a "sacrificial" electrode pos. 4 made of stainless steel, a semiconductor diode pos. 5, and the mounting screws pos. 5, stacker assembly pos. 7, consisting of a package of wire brush disks pos. 8. Power circuit design is provided by a nut 9.

The operation of the device is as follows.

Due to the formation of a galvanic cell, by detecting leakage currents using a semiconductor diode pos.5 and creating a potential difference between the device body pos.1 and the electrode pos.4, a cathode (protective ) potential that prevents the electrochemical destruction of the metal equipment of the well. The anode component of the induced potential through the elastic wire elements of the brush disks will be drained to the casing.

The design of the device can be used in installations of various mechanized production methods and injection wells.

Information sources:

1. Oilfield equipment: Handbook. / Ed. E.I. Bukhalenko. - 2nd ed., Revised. and add. - M .: Nedra, 1990 .-- 559 p .: silt, p. 53-58.

2 .. Patent for the invention No. 2217579; IPC 7 E21B 43/00, F04, D 13/10. Installation of a submersible centrifugal pump / A.G. Gazarov, T.S. Akhmerov, A.R. Epshtein, V.A. Kuznetsov - 2002108810/03; Claim 04/05/2002; Publ. November 27, 2003; Bull. No. 33.

3. Patent for utility model No. 80190. Corrosion protection device of a submersible pump unit / A.R. Mavzyutov, A.R. Epstein; Claim 07/14. 2008. Publ. 01/27/2009. Bull. Number 3.

Claims (1)

A corrosion protection device for a submersible pump installation, consisting of a threaded nipple screwed with a submersible motor, insulators and an electrode, characterized in that it further comprises a housing, a semiconductor diode, the anode of which is connected to the housing of the device, and the cathode to the electrode made of corrosion-resistant steel concentrically located inside the housing with the help of insulators, in the lower part of the electrode there is a stacker assembly consisting of a packet of wire brush disks, the material of which is Corrosion-resistant, high-alloy twisted steel is provided, the outer diameter of the disks corresponds to the inner diameter of the casing, providing guaranteed galvanic metal contact with the casing.