The impurities in petroleum products are easy to cause corrosion of oil casing, and the main component of these impurities is sulfide. Sulfide can react with water in oil to produce a large amount of hydrogen sulfide in petroleum. Hydrogen sulfide has reducibility and acidity, resulting in serious corrosion of petroleum equipment. In addition, there are a large number of other chemical impurities in the oil, which also largely caused the corrosion of petroleum equipment.
For oil casing corrosion protection, we should pay attention to the following points:
First of all, we should grasp the standards of water quality and strictly check and manage the water quality. Cleaning and separate injection should be carried out to strengthen the cleaning of main water pipeline so as to achieve the standard of water quality in station and well bottom and reduce the introduction of corrosive sources into annular space.
The annulus protective fluid mainly used for sterilization is put into the newly operation injection wells, and a system of periodic injection is formed.
In view of that mechanical abrasion accelerates the corrosion of oil casing, it is suggested to add a rubber ring to the tubing coupling or a centralizer to the serious deviation part of the well, to avoid the tubing scratching casing and the side contacting casing during operation and water injection.
In view of the serious corrosion of bacteria under scale and slow growth and killing of SRB at high temperature, high temperature water or steam of 100 degrees Celsius can be injected into annulus regularly to kill SRB under scale.
It is not recommended to popularize cathodic protection and Atlas casing until the corrosion in casing of water injection well is effectively controlled.