Glossary
Browse the IADC Lexicon alphabetically or by category. Get comprehensive definitions of drilling industry terms.
Dedendum
Definition(s)
Dedendum
The distance between the pitch line and root of thread. Source: API RP 7G, Recommended Practice for Drill Stem Design and Operating Limits, Upstream Segment, Sixteenth Edition, August 1998 (Addendum 2: September 2009). Global StandardsDecarburization
Definition(s)
Decarburization
The loss of carbon from the surface of a ferrous alloy as a result of heating in a medium that reacts with the carbon at the surface. Source: API RP 7G, Recommended Practice for Drill Stem Design and Operating Limits, Upstream Segment, Sixteenth Edition, August 1998 (Addendum 2: September 2009). Global StandardsDecarburization
Loss of carbon from the surface of a ferrous alloy as a result of heating in a medium that reacts with the carbon at the surface. Source: API SPEC 7-1, Specification for Rotary Drill Stem Elements, First Edition, March 2006 (Addendum April 2011). Global StandardsAnnuli
Definition(s)
Annuli
Plural of annulus. A well may contain several annuli formed by multiple casing and liner pipe strings. Source: API STD 65 – Part 2, Isolating Potential Flow Zones During Well Construction, Upstream Segment, Second Edition, December 2010. Global StandardsCritical Rotary Speed
Definition(s)
Critical Rotary Speed
A rotary speed at which harmonic vibrations occur. These vibrations may cause fatigue failures, excessive wear, or bending. Source: API RP 7G, Recommended Practice for Drill Stem Design and Operating Limits, Upstream Segment, Sixteenth Edition, August 1998 (Addendum 2: September 2009). Global StandardsCorrosion
Definition(s)
Corrosion
Degradation of a component or components due to corrosion. Corrosion may be categorized as either general or local and may cause pitting, holes, or crevices. Source: API RP 2SIM, Structural Integrity Management of Fixed Offshore Structures, First Edition, November 2014. Global StandardsCorrosion
The alteration and degradation of material by its environment. Source: API RP 7G, Recommended Practice for Drill Stem Design and Operating Limits, Upstream Segment, Sixteenth Edition, August 1998 (Addendum 2: September 2009). Global Standards Source: API RP 7G-2, Recommended Practice for Inspection and Classification of Used Drill Stem Elements, First Edition, August 2009. Global StandardsCorrosion
Corrosion as mentioned in this sub rule means both external and internal corrosion. Source: Guidance Notes on Petroleum and Natural Gas (Safety in Offshore Operations) Rules, 2008, Oil Industry Safety Directorate (India), 2012. Regulatory GuidanceCold Working
Definition(s)
Cold Working
Plastic deformation of metal at a temperature low enough to insure or cause permanent strain. Source: API RP 7G, Recommended Practice for Drill Stem Design and Operating Limits, Upstream Segment, Sixteenth Edition, August 1998 (Addendum 2: September 2009). Global StandardsCold Working
Plastic deformation of the thread roots of a rotary shouldered connection, of radii and of cylindrical sections at a temperature low enough to ensure or cause permanent strain of the metal. Source: API SPEC 7-1, Specification for Rotary Drill Stem Elements, First Edition, March 2006 (Addendum April 2011). Global StandardsClass 2
Definition(s)
Class 2
An API service classification for used drill pipe and tubing work strings. Source: API RP 7G, Recommended Practice for Drill Stem Design and Operating Limits, Upstream Segment, Sixteenth Edition, August 1998 (Addendum 2: September 2009). Global StandardsClass 2
Second in the hierarchy of used drill pipe service classifications for used drill pipe that does not meet premium class requirements. Source: API RP 7G-2, Recommended Practice for Inspection and Classification of Used Drill Stem Elements, First Edition, August 2009. Global StandardsBox Connection
Definition(s)
Box Connection
A threaded connection on Oil Country Tubular Goods (OCTG) that has internal (female) threads. Source: API RP 7G, Recommended Practice for Drill Stem Design and Operating Limits, Upstream Segment, Sixteenth Edition, August 1998 (Addendum 2: September 2009). Global StandardsBox Connection
Threaded connection on oilfield tubular goods (OCTG) that has internal (female) threads. Source: API SPEC 7-1, Specification for Rotary Drill Stem Elements, First Edition, March 2006 (Addendum April 2011). Global StandardsBit Sub
Definition(s)
Bit Sub
A sub, usually with 2 box connections, that is used to connect the bit to the drill string. Source: API RP 7G, Recommended Practice for Drill Stem Design and Operating Limits, Upstream Segment, Sixteenth Edition, August 1998 (Addendum 2: September 2009). Global StandardsBit Sub
Sub, usually with two box connections, that is used to connect the bit to the drill stem. Source: API RP 7G-2, Recommended Practice for Inspection and Classification of Used Drill Stem Elements, First Edition, August 2009. Global Standards Source: API SPEC 7-1, Specification for Rotary Drill Stem Elements, First Edition, March 2006 (Addendum April 2011). Global StandardsBevel Diameter
Definition(s)
Bevel Diameter
The outer diameter of the contact face of the rotary shouldered connection. Source: API RP 7G, Recommended Practice for Drill Stem Design and Operating Limits, Upstream Segment, Sixteenth Edition, August 1998 (Addendum 2: September 2009). Global Standards Source: API RP 7G-2, Recommended Practice for Inspection and Classification of Used Drill Stem Elements, First Edition, August 2009. Global StandardsBevel Diameter
Outer diameter of the sealing shoulder of a rotary shouldered connection. Source: API SPEC 5DP, Specification for Drill Pipe, First Edition, August 2009. Global StandardsBevel Diameter
Outer diameter of the contact face of the rotary shouldered connection. Source: API SPEC 7-1, Specification for Rotary Drill Stem Elements, First Edition, March 2006 (Addendum April 2011). Global StandardsAnnular Pressure Buildup (APB)
Definition(s)
Annular pressure buildup (APB)
Pressure generated within an annulus by thermal expansion of wellbore fluids, typically during production. NOTE APB can also occur during drilling operations when trapped annular fluids at cool shallow depths are exposed to high temperatures induced by fluids circulating from deep, hot hole sections. This thermally induced pressure is defined and listed in API 90 as thermal casing pressure. NOTE 2 Can also occur from migration of formation fluids, as defined in API 90. Source: API RP 96, Deepwater Well Design and Construction, First Edition, March 2013. Global StandardsAnnular Pressure Buildup (APB)
Pressure generated within a sealed annulus by thermal expansion of trapped wellbore fluids typically during production. May also occur during drilling operations when trapped annular fluids at cool shallow depths are exposed to high temperatures from fluids circulating in deep, hot hole sections. This thermally induced pressure is defined and listed in API RP 90 as thermal casing pressure. APB is also referred to as annular fluid expansion (AFE). Source: API STD 65 – Part 2, Isolating Potential Flow Zones During Well Construction, Upstream Segment, Second Edition, December 2010. Global StandardsAnnular Packers and Seal Rings
Definition(s)
Annular Packers and Seal Rings
Mechanical barrier devices with flexible, elastomeric sealing elements that can be run into a well on casing or liners for application as: a) annular element installed between an inner and outer pipe or between a casing and openhole formation to seal the annulus, b) annular seal rings installed on the inner pipe string to seal the micro-annulus and voids formed between the cement sheath and the inner pipe string. Source: API STD 65 – Part 2, Isolating Potential Flow Zones During Well Construction, Upstream Segment, Second Edition, December 2010. Global StandardsVME
Definition(s)
VME
Von Mises equivalent stress. Source: API RP 5C5, Recommended Practice on Procedures for Testing Casing and Tubing Connections, Third Edition, July 2003 (Reaffirmed August 2010). Global StandardsTSC
Definition(s)
TSC
Thread sealing connection. Source: API RP 5C5, Recommended Practice on Procedures for Testing Casing and Tubing Connections, Third Edition, July 2003 (Reaffirmed August 2010). Global StandardsTLE
Definition(s)
TLE
Test load envelope. Source: API RP 5C5, Recommended Practice on Procedures for Testing Casing and Tubing Connections, Third Edition, July 2003 (Reaffirmed August 2010). Global StandardsTC
Definition(s)
TC
Thermal cycle. Source: API RP 5C5, Recommended Practice on Procedures for Testing Casing and Tubing Connections, Third Edition, July 2003 (Reaffirmed August 2010). Global StandardsT&C
Threaded and coupled. Source: API SPEC 5CT, Specification for Casing and Tubing, Upstream Segment, Ninth Edition, July 2011 (Errata September 2012). Global StandardsTC
Test coupon. Source: API SPEC 6A, Specification for Wellhead and Christmas Tree Equipment, Twentieth Edition, October 2010 (Addendum November 2012). Global StandardsTC
To contain. Source: API SPEC 13A, Specification for Drilling Fluids Materials, Eighteenth Edition, February 2010. Global StandardsTC
Transport Canada. Source: Offshore Physical Environmental Guidelines, The Canada-Newfoundland and Labrador Offshore Petroleum Board, Canada-Nova Scotia Offshore Petroleum Board, and National Energy Board, Canada, September 2008. Regulatory GuidanceStd
Definition(s)
Std
Standard. Source: API RP 5C5, Recommended Practice on Procedures for Testing Casing and Tubing Connections, Third Edition, July 2003 (Reaffirmed August 2010). Global Standards Source: API RP 14G, Recommended Practice for Fire Prevention and Control on Fixed Open-type Offshore Production Platforms: Upstream Segment, Fourth Edition, April 2007. Global StandardsAnnular Flow
Definition(s)
Annular Flow
The flow of formation fluids (liquids and/or gases) from the formation into a space or pathway in an annulus within a well. The annular flow may follow various flow paths inside the annulus to other points including those at shallower or deeper depths. Source: API STD 65 – Part 2, Isolating Potential Flow Zones During Well Construction, Upstream Segment, Second Edition, December 2010. Global StandardsSRG
Definition(s)
SRG
Seal ring groove. Source: API RP 5C5, Recommended Practice on Procedures for Testing Casing and Tubing Connections, Third Edition, July 2003 (Reaffirmed August 2010). Global StandardsSRG
Stress-relief groove. Source: API RP 7G-2, Recommended Practice for Inspection and Classification of Used Drill Stem Elements, First Edition, August 2009. Global StandardsRS
Definition(s)
RS
Resilient seal. Source: API RP 5C5, Recommended Practice on Procedures for Testing Casing and Tubing Connections, Third Edition, July 2003 (Reaffirmed August 2010). Global StandardsRRG
Definition(s)
RRG
Round-robin galling test specimen condition. Source: API RP 5C5, Recommended Practice on Procedures for Testing Casing and Tubing Connections, Third Edition, July 2003 (Reaffirmed August 2010). Global StandardsR/Min
Definition(s)
R/Min
Revolutions per minute. Source: API RP 5C5, Recommended Practice on Procedures for Testing Casing and Tubing Connections, Third Edition, July 2003 (Reaffirmed August 2010). Global StandardsAmbient Pressure
Definition(s)
Ambient Pressure
Pressure external to the wellhead- Note 1 to entry: In the case of a surface wellhead, the pressure is 0 kPa (0 psig). In the case of a subsea wellhead, it is equal to the hydrostatic pressure of seawater at the depth of the subsea wellhead.