Casing is a series of steel pipes installed in a wellbore to maintain well integrity, ensure safety, and isolate different subsurface formations. After installation, each casing string is cemented in place.
Main casing types include:
✓ Conductor Pipe – Provides initial well stability and supports surface equipment
✓ Surface Casing – Protects freshwater zones and enables BOP installation
✓ Intermediate Casing – Isolates troublesome formations and manages pressure changes
✓ Liner String – Does not reach the surface; used to save cost and add zonal isolation
✓ Production Casing – Allows safe production of oil or gas from the reservoir
Proper casing design is critical for safe, efficient, and long-term well performance.