Definition(s)
Concentric Tubing
Small diameter tubing installed inside conventional tubing or tubingless completions, normally with the christmas tree in place, using a small rig or hoisting unit.
Source: API BULLETIN E3, Environmental Guidance Document: Well Abandonment and Inactive Well Practices for U.S. Exploration and Production Operations, First Edition, January 1993 (Reaffirmed June 2000). Global Standards