The pressure resulting from restriction of fluid flow downstream.
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
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
Backpressure (casing pressure, choke pressure)
The pressure existing at the surface on the casing side of the drill string/annulus flow system.
Source: API RP 59, Recommended Practice for Well Control Operations, Second Edition, May 2006. Global Standards