What problems may occur in the long-term use of oil casing pipe?

During the long-term use of oil casing pipe, due to the influence of various complex factors, the following problems may occur:

1. Corrosion problem

a. Electrochemical corrosion: The casing is in contact with electrolytes such as formation water and drilling fluid, forming a primary battery, which causes electrochemical corrosion of the casing.
b. Chemical corrosion: Corrosive media such as hydrogen sulfide and carbon dioxide in the formation will react chemically with the casing, causing casing corrosion.

c. Microbial corrosion: The metabolic products of certain microorganisms will corrode the casing, especially under high temperature and high pressure environments.

2. Mechanical damage

a. Wear: Friction between the casing and the drill pipe, formation rock, etc. causes the casing wall thickness to decrease and even perforation.
b. Deformation: Factors such as formation pressure and temperature changes can cause deformations such as bending and twisting of the casing, affecting its sealing performance.
c. Fracture: Due to material defects, stress concentration, fatigue damage and other reasons, the casing may break, causing serious accidents.
d. Stress fatigue: Oil casing subjected to external loads for a long time will produce stress fatigue, causing deformation, cracking or breaking of the pipeline, resulting in equipment failure and production accidents.

3. Seal failure

Oil casing may leak due to looseness or damage at the connection or sealing part, causing environmental pollution and safety hazards.

a. Threaded connection failure: The threaded connection is not sealed tightly, resulting in oil and gas leakage.
b. Casing damage: Cracks, holes and other damages in the oil casing lead to oil and gas leakage.
c. Cement ring failure: Cracks, detachment and other failures in the cement ring between the oil casing and the well wall lead to oil and gas channeling.
d. Alienation: The oil casing may become loose or alienated due to vibration, impact or temperature changes, resulting in pipeline rupture or oil leakage.

4. Other problems

a. Scaling: Long-term use of oil casing may accumulate scaling substances inside the pipeline, affecting fluid transmission efficiency and equipment operation stability. Minerals in formation water are deposited on the surface of the casing, forming scaling, which affects the flow of oil and gas.
b. Blockage: Drilling fluid, completion fluid and other substances are deposited in the casing, causing blockage and affecting oil and gas production.

c. Aging: After long-term use, the material properties of the casing will gradually decline and aging will occur.

Preventive measures:
1. In order to extend the service life of the oil casing and reduce the occurrence of problems, the following preventive measures can be taken:
2. Select suitable oil casing pipe materials: According to the geological conditions and mining methods of the oil and gas fields, select casing materials with good corrosion resistance, high strength and high toughness.
3. Optimize casing design: Reasonably design the wall thickness, threaded connection and other structures of the casing to improve its anti-squeeze, anti-internal pressure, anti-corrosion and other properties.
4. Strengthen construction quality control: Strictly control the transportation, storage, installation and other links of the casing to avoid damage to the casing.

5. Regular inspection and maintenance: Regularly inspect the casing to detect and deal with potential problems in a timely manner and extend its service life.

Conclusion:

Long-term use of oil casing pipe may cause corrosion, mechanical damage, seal failure and other problems. Effective preventive measures need to be taken to strengthen inspection and maintenance to ensure the safe and reliable operation of the casing pipe.

Read more: OCTG Casing Pipe Size Chart or Types of Drilling Casing Pipe