Cathodic Protection Solution for Oil Wells and Electric Submersible Pumps (ESP)
Submersible oilfield equipment operates in aggressive environments with elevated levels of carbon dioxide and hydrogen sulfide, which significantly increases the risk of corrosion. More than 60% of the country's annual oil production is extracted using electric submersible pump (ESP) units, making the protection and service life extension of downhole equipment a critical task.
The use of inhibitors is a popular method but not always effective. The injection of reagents into the productive formation is limited by geological features, difficult to regulate, and requires high consumption. Therefore, chemical treatment is mainly used in wells where the use of other methods of combating paraffin and salt deposits is either not possible or less effective than other methods.
Oil Well Submersible Aluminum Anode for ESP Protection
One of the methods for protecting oil well equipment from corrosion in complicated geological conditions is the use of sacrificial anodes made of aluminum alloys. The anodes are placed at the bottom of the descending tubing string in production wells or attached to the ESP motor via a threaded connection. An additional benefit of using the anode is equipment protection and control of paraffin and salt deposits. Installation of two or more anodes is possible.
The device is made of an aluminum sacrificial alloy with a suspension assembly inside. Due to its longitudinal ribs, the anode also functions as a centralizer, preventing mechanical damage to the ESP during descent into the well.
The devices are manufactured with outer diameters of 115 mm and 120 mm or according to the dimensions of the pump unit.
Device modifications:
- PSS-115U, PSS-120U are manufactured with an extended suspension rod along the body of the anode.
- PSS-115T, PSS-120T are made with a suspension assembly from tubing 60x5, with end parts protruding outside the anode body on both sides.
- PSS-115TS, PSS-120TS are manufactured with a suspension assembly from tubing 60x5 and a brush contact.
The anode polarizes the steel to a safe potential, as a result of which it dissolves, protecting the submersible equipment from corrosion. This technology is characterized by relatively low cost and long service life.
The design of the anode allows for its replacement after the service life ends. Anodes can be manufactured with customized alloy composition based on the specific formation fluid and in different sizes.
Intra-pipe Aluminum Anode
The intra-pipe anode for corrosion protection is designed to reduce the corrosion rate in tubing couplings and lift connections, where corrosion is usually most intense. The process is based on converting the anodic zone of tubing couplings into a cathodic one by installing anodes made of non-ferrous metal alloys in the couplings. As a result, the anodes become the sacrificial component that takes on the electrochemical corrosion process.
Flange Anode
Flange anodes are designed to reduce internal corrosion rates in pipelines and their elements. The process is based on converting the anodic zone of pipe and fitting joints, bellows compensators, and other pipeline components made of dissimilar metals into a cathodic zone by installing anodes made of zinc alloys in coupling joints. The anodes are installed at each flange along the direction of fluid flow. For permanently closed valves and in areas with changing flow direction, anodes are installed on both sides of the valve. The anode design allows for replacement after the service life ends.
Corrosion Rate Sensor – Anode Ladder Corrosion Control
The sensor allows for obtaining data on the dissolution rate of submersible anodes, enabling timely replacement planning to prevent downhole equipment failure due to corrosion. The sensor is lowered into the well along with the submersible equipment.
