Space between the inner diameter of pipe A and the outer diameter of pipe B when pipe B is positioned inside pipe A.
Source: API Specification 16Q, Design, Selection, Operation, and Maintenance of Marine Drilling Riser Systems, Second Edition, April 2017. Global Standards
The space between the outer wall of one string of pipe (casing or tubing) suspended in a wellbore and the inner wall of the next larger casing or the borehole wall; i.e., the space between concentric pipe strings.
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
Space surrounding the pipe in the wellbore. NOTE The outer wall of the annular space may be either surface or casing.
Source: API RP 10B-2, Recommended Practice for Testing Well Cements, First Edition, July 2005 (Reaffirmed: July 2010). Global Standards
Any space between concentric tubulars or between the tubular and the wellbore (formation).
Source: API RP 96, Deepwater Well Design and Construction, First Edition, March 2013. Global Standards
The space between two pipes, when one pipe is laterally positioned inside the other.
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
Space between two concentric plastic sheaths of an unbonded flexible pipe cross-section.
Source: API RP 17B, Recommended Practice for Flexible Pipe, Fourth Edition, July 2008. Global Standards
The space between the drill string and the inside diameter of the hole being drilled, the last string of casing set in the well, or the marine riser.
Source: API RP 59, Recommended Practice for Well Control Operations, Second Edition, May 2006. Global Standards
Source: API RP 64, Recommended Practice for Diverter Systems Equipment and Operations, Second Edition, November 2001 (March 1, 2007). Global Standards
Space between the internal pressure sheath and outer sheath. NOTE Permeated gas and liquid is generally free to move and mix in the annulus.
Source: API SPEC 17J, Specification for Unbonded Flexible Pipe, Third Edition, July 2008. Global Standards
The space between the borehole and tubulars or between tubulars, where fluid can flow. The annulus designation between the production tubing and production casing is the “A” annulus. Outer annuli between other strings are designated B, C, D, etc. as the pipe sizes increase in diameter.
Source: API STD 65 – Part 2, Isolating Potential Flow Zones During Well Construction, Upstream Segment, Second Edition, December 2010. Global Standards
“Annulus” means the space between a wellbore and tubulars or between tubulars where fluid can flow.
Source: Division of Mineral Resources Management – Oil and Gas, Ohio Administrative Code, Chapter 1501:9, January 2012. Regulations
Space between two pipes when one pipe is inside the other.
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