A completion riser is a riser that is designed to be run through the drilling marine riser and subsea BOP stack, and is used for the installation and recovery of the downhole tubing and tubing hanger in a subsea well. Since the completion riser is run inside a drilling marine riser, it is not exposed to environmental forces such as wind, waves and current.
A completion riser typically consists of the following (see Figure A.32): TH running tool; TH orientation device (unless this is included in the design of the TH itself, as can be done for example if a subsea HXT is used, or if a TH spool is used with a VXT); a means of sealing off against the riser inside the BOP stack for pressure-testing and well control; a subsea test tree for well control during an emergency disconnect; retainer valve(s) to retain the fluid contents of the riser during an emergency disconnect; intermediate riser joints; lubricator valve(s) to isolate the riser during loading/unloading of long wireline toolstrings; a surface tree for pressure control of the wellbore and to provide a connection point for a surface wireline lubricator system; a means of tensioning the riser, so that it does not buckle under its own weight.
Source: API RP 17A, Design and Operation of Subsea Production Systems—General Requirements and Recommendations, Fourth Edition, Reaffirmed 2011. Global Standards
Temporary riser that is designed to run inside a BOP and drilling riser to allow for well completion. NOTE Completion operations are performed within the drilling riser. A completion riser can also be used for open-sea workover operations.
Source: API RP 17G, Recommended Practice for Completion/Workover Risers, Second Edition, July 2006 (Reaffirmed April 2011). Global Standards