Oil well casing is the barrier that isolates the formation from the wellbore during drilling. Casing damage is particularly common in heavy oil thermal recovery wells. The main damage manifests itself as extrusion deformation, distortion, etc.
Causes of oil well casing damage:
1. Mechanical wear: The casing continuously moves up and down in the oil wellbore and rubs against the well wall, gradually causing wear. Moreover, oil wells contain hard objects such as sand, which will cause more obvious wear and tear on the casing.
2. Corrosion damage: Casing must withstand the corrosive effects of various acids, alkalis, salts and other chemical substances in oil wells. Corrosion damage occurs over time.
3. Damage from external forces: During long-term operation, oil well casing will inevitably be impacted by some external forces, such as drill bit impact, worker smashing, etc.
4. Thermal expansion and contraction: Oil wells will generate high and low temperatures during the production process, so the casing will expand and contract due to heat, which will cause damage to the casing over time.
Types of oil well casing damage:
1. Scratches: longitudinal or spiral grooves are drawn on the surface of the casing.
2. Wear: The surface of the casing is ground into boss-shaped or oval grooves.
3. Corrosion: Chemical corrosion marks appear on the metal on the surface of the casing, and rust spots or holes appear on the surface of the casing.
4. Crack: The metal on the surface of the casing is cracked, and the inner wall is cracked and broken.
5. Deformation: The casing is subject to external forces, resulting in bending and torsional deformation.
6. Fracture: Longitudinal or transverse cracks appear in the casing, causing the casing to rupture.
