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The Principle of Oil Well Casing Cathodic Protection Technology

Date:2020-05-11    keywords:well casing,cathodic protection technolog,principle
The damage to the wellbore structure of oil fields and water wells not only affects the normal production of damaged wells, but also affects the normal development of adjacent wells and even blocks, and poses a great threat to the stable production of the entire oil field.

Oil well casing cathodic protection technology:
There are two types of cathodic protection technology: sacrificial anode cathodic protection and forced current (impressed current) cathodic protection.

Sacrificial anode cathodic protection technology:
Sacrificial anode cathodic protection technology is to use a metal or alloy with a potential that is more negative than the metal to be protected to electrically connect with the protected metal, relying on the current generated by the metal with a more negative potential to continuously corrode and dissolve to protect other metal.

As a sacrificial anode material, it must meet the following requirements: ① must have a sufficiently negative stable potential; ② self-corrosion rate is small and the corrosion is uniform, and a high and stable current efficiency; ③ high electrochemical equivalent, that is, the electricity generated per unit weight Large flow rate, ④The anode polarization should be small during work, and the product is easy to fall off. ⑤Corrosion products do not pollute the environment and are harmless. ⑥The material source is wide, the processing is easy, and the price is low. Forced current cathodic protection technology. The forced current method is to pass a cathode current directly from the external DC power supply to the metal to be protected, so that the metal to be protected becomes a cathode to achieve the purpose of cathodic protection.

According to the solubility of anodes, auxiliary anodes can be divided into three categories: soluble anodes (such as steel, aluminum), slightly soluble anodes (such as high-silicon cast iron, graphite), and insoluble anodes (such as platinum, platinum plating, and metal oxides). DC power supply is a power source for forced current. Its basic requirements are stable and reliable, can run continuously for a long time, and adapt to various environmental conditions.

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