Coiled Tubing is a continuous length of small-diameter steel pipe, typically ranging from 1 inch to 3.25 inches in diameter, wound on a large spool. It can be inserted into a wellbore without having to remove the existing tubing, allowing for live well interventions.
Key Features of Coiled Tubing Operations
- Continuous Pipe: The tubing is spooled on a reel and can be deployed into the well quickly and efficiently.
- Pressure Control: CT operations can be performed under pressure using blowout preventers (BOPs) and pressure control heads.
- Live Well Capabilities: Allows for intervention in wells without killing them, preserving reservoir pressure.
Common Applications:
- Cleanouts: Removing sand, scale, or fill material using nitrogen or fluid circulation.
- Acidizing: Delivering acid to specific zones to enhance production.
- Logging and Perforating: Running tools to gather well data or create perforations.
- Fishing: Retrieving stuck tools or debris from the wellbore.
- Hydraulic Fracturing (Mini-Fracs): Targeted stimulation in low-permeability zones.
- Cementing: Spotting cement in specific sections for plugging or zonal isolation.
Advantages:
Reduced well downtime
Cost-effective compared to traditional workover rigs
Fast mobilization and operation
Live well intervention capability
Challenges and Limitations:
Limited mechanical strength compared to jointed pipe
Fatigue due to repeated bending/unbending
Limited reach in highly deviated or horizontal wells without friction reduction methods