Definition(s)
Riser Annulus
Space between the riser string inner diameter and the outer diameter of the pipe (drill pipe, casing, tubing) suspended inside the riser string
Source: API Specification 16Q, Design, Selection, Operation, and Maintenance of Marine Drilling Riser Systems, Second Edition, April 2017. Global Standards
Riser Annulus
The space around a pipe (drillpipe, casing or tubing) suspended in a riser; its outer boundary is the internal surface of the riser pipe.
Source: API RP 16Q, Recommended Practice for Design, Selection, Operation and Maintenance of Marine Drilling Riser Systems, First Edition, November 1993 (Reaffirmed August 2001). Global Standards
Riser Annulus
Space around a pipe (drillpipe, casing or tubing) suspended in a riser. NOTE Its outer boundary is the internal surface of the riser pipe.
Source: ISO 13624-1:2009, Petroleum and natural gas industries – Drilling and production equipment – Part 1:Design and operation of marine drilling riser equipment. Global Standards