Glossary
Browse the IADC Lexicon alphabetically or by category. Get comprehensive definitions of drilling industry terms.
Squeeze Pressure
Definition(s)
Squeeze Pressure
That surface pressure required to force a cement slurry into the location desired and result in a differential pressure across the cement slurry that causes cement particles to separate from water (i.e. dehydration) and form a filter cake. 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 StandardsSqueeze Cementing
Definition(s)
Squeeze Cementing
Pumping a cement slurry to a specific point in the wellbore with sufficient pressure to force the cement into the location desired. This pressure will also tend to dehydrate the cement and form a high strength filter cake in perforations, in formation voids or fractures, or against the formation face. The filter cake becomes a barrier which will prevent fluid movement. Squeeze cementing is used to seal completion intervals, to repair casing leaks, to seal formation intervals behind pipe, and to protect fresh water aquifers. 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 StandardsSqueeze-Cementing
Remedial process in which cementing material is forced under pressure into a specific portion of the well such as a fracture or opening. Source: API RP 10B-2, Recommended Practice for Testing Well Cements, First Edition, July 2005 (Reaffirmed: July 2010). Global StandardsSlim Hole Completion
Definition(s)
Slim Hole Completion
A well that is completed without tubing. Usually, only small diameter casing is set and cemented. After perforating, formation fluids are produced out of the casing. 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 StandardsRetrievable Packer
Definition(s)
Retrievable Packer
A tool consisting of slips, an open mandrel, and rubber sealing elements run on workstring or tubing to isolate the wellbore h m pressures encountered during squeeze cementing operations. The tool is intended to be set and released several times by methods specific to the tool design (i.e., tension or compression set). 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 StandardsProductive Horizon
Definition(s)
Productive Horizon
Any stratum known to contain oil, gas, or geothermal resources in commercial quantities. 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 StandardsProductive Horizon
Any stratum known to contain oil, gas, or geothermal resources in commercial quantities in the area. Source: Oil and Gas Division, Texas Administrative Code, Title 16, Chapter 3, February 2013. RegulationsPlug Back Total Depth
Definition(s)
Plug Back Total Depth (PBTD)
The new bottom of a well that is established when a well is plugged back. 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 StandardsPlug Back
Definition(s)
Plug Back
To place cement or other material in the well to seal off a completion interval, to exclude bottom water, or to perform another operation such as side-tracking or producing from another depth. The term also refers to the setting of a mechanical plug in the casing. 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 StandardsPlug and Abandon
Definition(s)
Plug and Abandon
Placement of a cement plug or plugs in a well, in which no future utility has been identified, to seal the entire wellbore against fluid migration, and protect fresh water aquifers from contamination. 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 StandardsPlug
Definition(s)
Plug
A device or material which may be temporarily or permanently placed in the wellbore to block off or isolate lower zones so that upper zones may be completed, stimulated, tested, cemented, produced, or injected into. 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 StandardsPlug
"Plug" means the closing off, in a manner prescribed by the Commission, of all oil, gas, and waterbearing formations in any producing or nonproducing wellbore before such well is abandoned. Source: Corporation Commission, Oil and Gas Conservation, Oklahoma Administrative Code 165:10, February 2013. RegulationsPermeability
Definition(s)
Permeability
The property of a porous medium which is a measure of the capacity of the medium to transmit fluids within its interconnected pore network. The usual unit of measurement is the millidarcy, or 0.001 darcy. 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 StandardsPermeability
Measure of the ease with which material can become magnetized. NOTE Permeability is the ratio of flux density and magnetizing force, i.e. B/H. Source: API RP 5A5, Field Inspection of New Casing, Tubing, and Plain-end Drill Pipe, Reaffirmed August 2010. Global StandardsPermeability
Measure of the capacity of a porous medium to allow flow of fluids or gases. NOTE Permeability is usually expressed in millidarcy, mD. Source: API RP 10B-2, Recommended Practice for Testing Well Cements, First Edition, July 2005 (Reaffirmed: July 2010). Global StandardsPermeability
Permeability of a space means the ratio of the volume within that space which is assumed to be occupied by water to the total volume of that space. Source: Resolution MEPC.119(52), 2004 amendments to the International Code for the Construction and Equipment of Ships Carrying Dangerous Chemicals in Bulk (IBC Code), 15 October 2004, International Maritime Organization. Regulatory GuidancePermeability (μ)
Permeability ( of a space is the proportion of the immersed volume of that space which can be occupied by water. <Chapter II-1, regulation 2>. Source: IMO Resolution MSC.216(82), amendments to the International Convention for the Safety of Life at Sea, 1974, as amended, 8 December 2006, International Maritime Organization. LegislationPermeability
“Permeability” in relation to a space is the ratio of the volume within that space which is assumed to be occupied by water to the total volume of that space. Source: IMO Resolution MSC.266(84), Code of Safety for Special Purpose Ships, 2008 (2008 SPS Code), 13 May 2008, International Maritime Organization. Regulatory GuidancepH
Definition(s)
pH
A unit to measure the degree of acidity or alkalinity of a liquid. A neutral solution, such as pure water, has a pH of 7. Acidic solutions have a pH less than 7. Alkaline solutions have a pH greater than 7. 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 StandardspH
The term “pH” denotes the negative logarithm of the hydrogen ion, H+, activity in aqueous solutions (activity and concentration are equal only in dilute solutions): pH = log [H+]. For pure water at 24 °C (75 °F) the hydrogen ion activity [H+] is 10-7 mol/l and pH 7. This system is termed “neutral” because the hydroxyl ion activity [OH ] is also 10-7 mol/l. In aqueous systems at 24 °C (75 °F) the ion product, [H+] [OH-], is 10-14 (a constant). Consequently, an increase in H+denotes a like decrease in [OH-]. A change in pH of one unit indicates a ten-fold change in both [H+] and [OH-]. Solutions with pH less than 7 are termed “acidic” and those with pH greater than 7 are termed “basic” or “alkaline”. Source: API RP 13B-1, Recommended Practice for Field Testing Water-based Drilling Fluids, Fourth Edition, March 2009. Global StandardsPH
Piloted hydraulic. Source: API SPEC 17F, Specification for Subsea Production Control Systems, Second Edition, December 2006 (Reaffirmed April 2011). Global StandardsMud
Definition(s)
Mud
The weighted liquid circulated through the wellbore during rotary drilling and workover operations. In addition to its function of bringing cuttings to the surface, drilling mud cools and lubricates the bit and drill stem, protects against blowouts by holding back subsurface pressures, and deposits a mud cake on the wall of the borehole to prevent loss of fluids into the formation. Originally a suspension of clays in water, the mud used in modem drilling is often a more complex mixture of liquids, reactive solids, or oil, often containing one or more conditioners. Water base mud made from oil field brine may also be used as a well control fluid in plugging operations. Also known as drilling fluid or drilling mud. 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 StandardsMud
Fluid that is circulated through the wellbore during drilling or workover operations. Source: API RP 10B-2, Recommended Practice for Testing Well Cements, First Edition, July 2005 (Reaffirmed: July 2010). Global StandardsMud
Slurry of insoluble and soluble solids in either a water, synthetic or oil continuous-phase fluid. cf. drilling fluid (3.1.34). Source: API RP 13C, Recommended Practice on Drilling Fluids Processing Systems Evaluation, Upstream Segment, Fourth Edition, December 2010. Global StandardsMud
See Drilling Fluid. Source: API Specification 16Q, Design, Selection, Operation, and Maintenance of Marine Drilling Riser Systems, Second Edition, April 2017. Global Standards 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 StandardsMud
"Mud" means any mixture of water and clay or other material as the term is commonly used in the industry. Source: Corporation Commission, Oil and Gas Conservation, Oklahoma Administrative Code 165:10, February 2013. RegulationsMud
Water- or oil-based fluid circulated down the drillpipe into the well and back up to the rig for purposes including containment of formation pressure, the removal of cuttings, bit lubrication and cooling, treating the wall of the well and providing a source for well data. 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 StandardsMechanical Integrity
Definition(s)
Mechanical Integrity
Defined by EPA as "no significant leak in the casing, tubing, and packer and no significant fluid movement into a USDW through vertical channels adjacent to the injection wellbore." 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 StandardsLanding Nipple
Definition(s)
Landing Nipple
A receptacle that can be installed in a tubing string with an internal profile machined to provide a seating surface whereby various types of plugs or valves can be latched and will seal against the machined surface. 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 StandardsIntermediate Casing
Definition(s)
Intermediate Casing
One or more strings of casing run between the surface casing and the production casing or the production liner and is cemented in place. intermediate casing is generally run in deeper wells to isolate abnormal pressured formations, lost circulation zones, salt sections, and unstable shale sections so deeper drilling can proceed with normal mud weights. A large number of wells are drilled without running intermediate casing. 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 StandardsIntermediate Casing
Casing that is set when geological characteristics or wellbore conditions require isolation. These conditions include, but are not limited to, prevention of lost circulation, formation fluid influx or hole instability. Multiple intermediate casing strings can be run in a single well. Source: API STD 65 – Part 2, Isolating Potential Flow Zones During Well Construction, Upstream Segment, Second Edition, December 2010. Global StandardsIntermediate Casing
Long casing string (12 1/4 in. drift, sizes range 13 3/8 in. to 14 in.) with casing hanger in the subsea wellhead housing. Normal clearance casing OD in.: 13 3/8. Tight clearance casing OD in.: 13 5/8. NOTE These are examples only. Each well can have variations in number of casing strings and sizes. Naming conventions can vary. The heavy-wall surface casing designs may allow 13 5/8 in. to be run as a liner and not tied back. Source: API RP 96, Deepwater Well Design and Construction, First Edition, March 2013. Global StandardsIntermediate Casing
"Intermediate casing" means a casing string run between the surface casing and the production casing or production liner and cemented in place to isolate abnormally geo-pressured strata, lost circulation zones, salt sections, or unstable shale sections. Source: Alaska Oil and Gas Conservation Commission, Definitions, Alaska Admin. Code tit. 20, § 25.990, December 7, 2012. RegulationsIntermediate Casing
"Intermediate casing" means the casing string or strings run after setting the surface casing and prior to setting the production string or liner. Source: Corporation Commission, Oil and Gas Conservation, Oklahoma Administrative Code 165:10, February 2013. RegulationsIntermediate Casing
“Intermediate casing” means one or more strings of casing set after surface casing has been cemented through the base of the deepest underground source of drinking water, but before drilling into the permitted hydrocarbon reservoir(s) to isolate hydrocarbon or brine bearing flow zones, stabilize the wellbore, to isolate protected groundwater if encountered after drilling below surface casing, isolate lost circulation zones or other potential geologic hazards, or serve as a base for well control equipment. Source: Division of Mineral Resources Management - Oil and Gas, Ohio Administrative Code, Chapter 1501:9, January 2012. RegulationsIntermediate Casing
Intermediate casing—A string of casing set after the surface casing and before production casing, not to include coal protection casing, that is used in the wellbore to isolate, stabilize or provide well control. Source: Oil and Gas Wells, Pennsylvania Code, Title 25, Chapter 78, December 2012. RegulationsInactive Well
Definition(s)
Inactive Well
A well where production, injection, disposal or workover operations have ceased, but permanent abandonment has not taken place. inactive wells should be classified as either shut-in or temporarily abandoned. Shut-in status should begin 90 days after operations stop, and temporarily abandoned status should commence one day after temporary abandonment operations have been completed. 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 StandardsInactive Well
INACTIVE WELL shall mean any shut-in well from which no production has been sold for a period of twelve (12) consecutive months; any well which has been temporarily abandoned for a period of six (6) consecutive months; or, any injection well which has not been utilized for a period of twelve (12) consecutive months. Source: Oil and Gas Conservation Commission, Practice and Procedure, Code of Colorado Regulations, 2 CCR 404-1, February 2013. RegulationsInactive Well
An unplugged well that has been spudded or has been equipped with cemented casing and that has had no reported production, disposal, injection, or other permitted activity for a period of greater than 12 months. Source: Oil and Gas Division, Texas Administrative Code, Title 16, Chapter 3, February 2013. RegulationsFluid Spacer
Definition(s)
Fluid Spacer
An oil or water based fluid used to separate incompatible drilling fluid from cement. Spacers are compatible with both the drilling fluid and the cement. The purpose of spacers is to minimize cement contamination by drillllig fluid and to displace drilling fluid from the wellbore 60 that the cement can form an effective hydraulic seal. 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 StandardsFloat Shoe
Definition(s)
Float Shoe
A guide shoe run on the bottom of the casing string that incorporates a ball or spring-loaded backpressure valve which prevents wellbore fluid from entering the casing while the pipe is lowered in the well. Performs the same function as the float collar. 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 StandardsFloat Collar
Definition(s)
Float Collar
A short cylindrical section of steel which is placed in the casing string above the guide shoe. The float collar usually incorporates a bail or spring-loaded backpressure valve which prevents wellbore fluid from entering the casing while the pipe is lowered in the well. This makes the casing buoyant, thereby reducing the derrick stress while running casing. 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 StandardsDump Bailer
Definition(s)
Dump Bailer
A cylindrical container with a shear device that is used to release small batches of cement downhole on impact or by electrical activation. Used primarily to install cement on downhole tools such as bridge plugs or cement retainers. 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 StandardsDisplacement Fluid
Definition(s)
Displacement Fluid
In oil well cementing, the fluid, usually drilling mud or salt water, that is pumped into the well after the cement is pumped to displace the cement from the casing and into the annulus and to prevent the cement from re-entering the casing after pumping stops. 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 StandardsCorrosive Oilfield Water
Definition(s)
Corrosive Oilfield Water
A water that induces corrosion of the casing, tubing, and wellhead because of low pH and elevated levels of temperature, pressure, bacteria, dissolved gases, and dissolved solids. The severity of the corrosion increases with an increase in the velocity of oilfield waters across the surfaces of the casing, tubing, and wellhead. Water found in fresh water aquifers typically is near ambient temperature, has low levels of dissolved gases and solids and has a relatively low velocity. As a result, fresh water aquifers are generally not very corrosive. 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 StandardsConcentric Tubing
Definition(s)
Concentric Tubing
Small diameter tubing installed inside conventional tubing or tubingless completions, normally with the christmas tree in place, using a small rig or hoisting unit. 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 StandardsCompletion Interval
Definition(s)
Completion Interval
The geologic formations in a well where production, injection or disposal operations are taking place. 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 StandardsCompletion Interval
“Completion interval” means a section within a well that is prepared to permit the- production of fluids from the well;
- observation of the performance of a reservoir; or
- injection of fluids into the well (intervalle de complétion).