First, corrosion prevention strategies for oil casing:

1. First, ensure water quality meets standards. Strictly monitor and manage water quality. Implement separate injection for clean and contaminated water, strengthen the cleaning of the main water pipeline, and ensure that the water quality in the station and at the bottom of the well meets standards to reduce the introduction of corrosion sources into the annular space.

2. For newly commissioned injection wells, adopt annular protection fluid mainly for sterilization, and establish a system for regular addition.

3. Given that mechanical abrasion accelerates corrosion of oil casing, it is recommended to add a rubber ring to the tubing coupling or a centralizer in areas of severe well deviation to prevent the tubing from scratching the casing or contacting the casing on one side during operation and water injection.

4. For severe under-scale bacterial corrosion and the slow growth and killing of SRB at high temperatures, high-temperature water or steam at 100 degrees Celsius can be injected into the annulus periodically to kill under-scale SRB.

5. Before corrosion inside the injection well casing is effectively controlled, it is not recommended to promote the use of cathodic protection and coated casing.

Second, Inspection Methods for Oil Casing

1. Ultrasonic Testing: When ultrasound propagates through the material being tested, the acoustic properties and internal structure of the material significantly affect its propagation. By detecting the level and extent of this influence, changes in the material’s properties and structure can be understood.

2. Radiographic Testing: Radiographic testing utilizes the difference in the amount of radiation transmitted between normal and defective areas, creating a difference in density on the film.

3. Penetrant Testing: Penetrant testing utilizes the capillary action of a liquid to penetrate the surface of a solid material through an open defect. A developer then draws the penetrant back to the surface, revealing the defect. Penetrant testing is suitable for various metal and ceramic workpieces, and the time from penetration to defect appearance is relatively short, typically about half an hour. It can detect surface fatigue, stress corrosion, and weld cracks, and can directly measure crack dimensions.

4. Magnetic particle testing: Magnetic particle testing utilizes the magnetic leakage at the defect to attract magnetic powder, forming a magnetic trace, which provides a visual indication of the defect. It can detect surface and subsurface defects, and the nature of the defect is easy to identify. Paint and electroplated surfaces will not affect the accuracy of the test.