A liner in well completions is a string of casing that does not extend to the surface. Typically, it is supported by an intermediate casing using a liner hanger. This article explores the types of liners, their applications, advantages, and potential challenges.
Types of Liners: Each with a Purpose
There are several types of liners as listed below.
Drilling Liners
Drilling Liners
- Utilized to address lost circulation or abnormal pressure zones, allowing for deeper drilling.
Production Liners
Production Liners
- Replaces a full casing to isolate production or injection zones.
Tie-Back Liner
Tie-Back Liner
- Extends from the top of an existing liner to the surface, with optional cementation.
Scab Liner
Scab Liners
- A non-surface-reaching casing section used for repairing damaged casing, often sealed with packers and cemented.
Scab Tie-Back Liner
Scab Tie Back Liners
- Extends from the top of an existing liner to the surface, typically cemented in place.
Advantages of Liners:
- Cost savings: They reduce the overall cost of your production string, saving you money on materials and installation.
- Time savings: Running and cementing liners is faster than full casings, meaning quicker completion times.
- Optimized tubing: Liners allow you to use larger tubing sizes for optimal production flow.
- Reduced wellhead load: Lighter liners mean less stress on your wellhead and surface piping.
- Heavy-duty solutions: Scab tie-back liners provide extra strength through demanding zones.
- Drilling flexibility: Use tapered drillstrings with ease thanks to liners.
- Rig limitations? No problem: Liners are lighter and can be used when rig capacity restricts heavy casings.
- Superior sealing: PBR completions with liners offer the best casing-to-tubing seal available.
- Enhanced flexibility: Liners offer more options for adjusting your completion design later on.
- Fresh start: Tie-back liners provide a pristine upper casing section, untouched by drilling.
- Critical testing: Conduct safe and controlled testing in sensitive areas with liners.
Disadvantages of Liners:
- Leakage risk: The liner hanger could leak, though proper installation minimizes this risk.
- Cementation challenges: The narrow space between the liner and the hole can make good cementation tricky.
Conclusion
Understanding the various types, advantages, and potential drawbacks of liners in well completions is crucial for optimizing well design and operational efficiency. Despite some challenges, liners offer significant benefits in terms of cost reduction, flexibility, and well completion customization.
References
Jonathan Bellarby, 2009. Well Completion Design, Volume 56 (Developments in Petroleum Science). 1 Edition. Elsevier Science.
Wan Renpu, 2011. Advanced Well Completion Engineering, Third Edition. 3 Edition. Gulf Professional Publishing.
Ted G. Byrom, 2014. Casing and Liners for Drilling and Completion, Second Edition: Design and Application (Gulf Drilling Guides). 2 Edition. Gulf Professional Publishing.
