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Oil Industry

Oilfield industry glossary of terms and acronyms

Adam

• 10 min read
Oilfield industry glossary of terms and acronyms

I need a most fully complete glossary of terms that are used in the oil field industry as well as full complete list of acronyms that are used in the oil industry. Everything from drilling, mudlog, engineering, geology, etc...

ChatGPT 5.2 said:

You’re asking for something the industry usually keeps as multiple references, because a truly “complete” oilfield glossary is thousands of entries (and acronyms can be even worse because many are company- or basin-specific). The most widely used canonical references are:

  • SLB (Schlumberger) Energy Glossary (claims 4,800+ reviewed definitions).
  • SPE / OnePetro E&P Glossary (PetroWiki legacy glossary preserved on OnePetro).
  • IADC drilling acronyms/abbreviations appendices (drilling-focused acronym + definition references).

Below is a big, practical “field” glossary + a heavy acronym pack that covers drilling, mudlogging, geology, petrophysics, completions, production, facilities, HSE, and offshore/subsea. (If you want, I can also deliver this as a CSV/Excel or a printable PDF handout.)

Oilfield glossary (high-coverage, field-focused)

A. Drilling rig, hole-making, and daily ops

  • Annulus — The space between two concentric tubulars (e.g., casing and drillpipe), or between casing and open hole.
  • API — American Petroleum Institute; also shorthand for API specs/standards and API gravity (see fluids).
  • Backream — Reaming while pulling out of hole to enlarge/clean the wellbore.
  • BHA (Bottomhole Assembly) — The downhole tool/tubular assembly below the drillpipe (collars, stabilizers, MWD/LWD, motor/RSS, bit).
  • Bit (PDC / tricone) — Cutting tool at the end of BHA used to drill formation.
  • Break circulation — Restore circulation after static period; check returns/pressures.
  • Caving / sloughing — Unstable formation shedding into the wellbore.
  • Cellar — Excavated area around wellhead/BOP base for access.
  • Conductor — Large-diameter first casing set to stabilize shallow hole / support wellhead.
  • Connection — Adding a joint/stand of pipe; drilling stops briefly.
  • Doghouse — Rig office / control room (traditional term).
  • Drawworks — Hoisting system (drum, brakes) that raises/lowers drillstring.
  • Drill string — Drillpipe + BHA (and sometimes HWDP, collars).
  • Drilling window — Safe mud-weight range between pore pressure and fracture gradient.
  • ECD (Equivalent Circulating Density) — Effective density while circulating (includes friction losses).
  • Flowline — Line carrying returns from well to shale shakers/mud system.
  • Hole cleaning — Removing cuttings from annulus via flow rate, rheology, RPM, sweeps, etc.
  • Hookload — Weight measured on the traveling block/hook; used for drag/torque diagnostics.
  • Kelly / top drive — Rotary power to drillstring (kelly = older; top drive = modern).
  • Kickoff point (KOP) — Depth where directional build starts (for deviated wells).
  • Lag time — Time for cuttings/gas to travel from bit to surface (critical in mudlogging).
  • MSE (Mechanical Specific Energy) — Energy per rock volume removed; drilling efficiency indicator.
  • NPT (Non-Productive Time) — Time not making planned progress (stuck pipe, repairs, waiting on weather, etc.).
  • POOH / RIH — Pull out of hole / Run in hole.
  • ROP (Rate of Penetration) — Drilling speed (ft/hr or m/hr).
  • Ream / reaming — Enlarge or smooth wellbore without deepening significantly.
  • Rotate vs slide — Rotate: string rotates; Slide: steer with motor/toolface without full rotation.
  • Shakers (shale shakers) — Vibratory screens that remove cuttings from returns.
  • Spud — Start of drilling (spud date = when well begins drilling).
  • Stand / single / joint — Stand = multiple joints racked together (often 2–3); single/joint = one pipe length.
  • Stabilizer — Tool that centralizes BHA and controls directional tendency.
  • Stick-slip — Torsional vibration (bit alternately sticks and slips), can damage tools/bit.
  • Top of fill (TOF) — Depth of cuttings fill in hole (often found while running in).
  • Torque & drag — Rotational resistance and axial friction indicators in directional wells.
  • Trip — Pulling and running drillstring (bit change, tool change, etc.).
  • Trip tank — Small calibrated tank used to measure gains/losses during trips.
  • Wiper trip — Trip to condition hole/clean wellbore without changing much else.

B. Well control, pressure, and integrity

  • BOP (Blowout Preventer) — Pressure-control equipment at wellhead to shut-in/control well.
  • Choke line / kill line — High-pressure lines used to circulate out influx and pump kill mud.
  • Casing shoe — Bottom of casing string (shoe track area includes float equipment).
  • FIT / LOT — Formation integrity test / leak-off test (checks fracture/strength at casing shoe).
  • Fracture gradient — Pressure per depth where formation breaks down.
  • Gas cut mud — Mud with entrained gas reducing effective density.
  • Influx — Entry of formation fluid into wellbore (kick).
  • Kick — Unplanned influx due to underbalance.
  • Kill sheet — Calculations/procedure to circulate out kick and restore control.
  • MASP / MAASP — Maximum allowable surface pressure / annular surface pressure.
  • Overbalance / underbalance — Mud hydrostatic greater than / less than formation pressure.
  • Pore pressure — Pressure of fluids in the pore spaces of rock.
  • Primary well control — Mud hydrostatic + ECD; prevents influx.
  • Secondary well control — BOP system; contains influx if it occurs.
  • Shut-in — Close BOP to stop flow; measure stabilized pressures.
  • SICP / SIDPP — Shut-in casing pressure / shut-in drillpipe pressure.
  • Wellbore breathing — Elastic gain/loss during pressure cycles (not true losses).
  • Wellbore ballooning — Similar concept; apparent losses/gains due to formation elasticity.

C. Drilling fluids (mud), solids control, and rheology

  • Mud / drilling fluid — Fluid used for pressure control, hole cleaning, lubrication, wellbore stability, etc.
  • WBM / OBM / SBM — Water-based / oil-based / synthetic-based mud.
  • NAF — Non-aqueous fluid (often OBM/SBM category).
  • Active system — Mud in circulation pits + lines; excludes reserves.
  • Barite — Common weighting material to increase mud density.
  • Bentonite — Clay used for viscosity/filtration control (WBM).
  • Brine — High-salinity fluid used in completion/workover fluids.
  • Centrifuge — Separates fine solids from mud.
  • Desander / desilter — Hydrocyclones removing sand/silt-sized solids.
  • Dilution — Adding base fluid to control solids/rheology.
  • Emulsion — Dispersion (OBM/SBM typically water-in-oil emulsion).
  • Filter cake — Solids layer deposited on wellbore wall during filtration.
  • Filtrate loss (fluid loss) — Liquid phase that invades formation during filtration.
  • Gel strength — Low-shear structure (10-sec/10-min gels); affects suspension.
  • HPHT — High pressure high temperature conditions affecting fluid behavior.
  • LCM (Lost Circulation Material) — Fibers/flakes/granules to seal loss zones.
  • Mud weight (MW) — Fluid density (ppg or sg); primary pressure control.
  • PV / YP — Plastic viscosity / yield point; key rheology parameters.
  • Sag — Weighting material settling (common risk in deviated wells/NAF).
  • Sweep — High-viscosity pill to improve hole cleaning.
  • TDS — Total dissolved solids (brines/water chemistry).
  • Water activity (aw) — Controls shale hydration; used in inhibitive systems.

D. Directional drilling, MWD/LWD, geosteering

  • Azimuth / inclination — Direction and angle from vertical.
  • Build / drop / turn — Increase inclination / decrease / change azimuth.
  • Dogleg severity (DLS) — Curvature measure (°/100 ft or °/30 m).
  • Geosteering — Real-time placement of wellbore within target interval using logs/cuttings/gas/seismic guidance.
  • LWD — Logging while drilling (formation measurements near bit).
  • MWD — Measurement while drilling (directional, vibration, basic sensors).
  • RSS — Rotary steerable system (steers while rotating).
  • Toolface — Orientation of downhole motor/RSS steering reference.
  • TVD / MD — True vertical depth / measured depth.
  • TVDSS — True vertical depth subsea (offshore datum).

E. Casing, cementing, and well construction

  • Casing string — Tubulars run to stabilize/isolate zones (surface, intermediate, production).
  • Centralizer — Keeps casing centered for better cement placement.
  • Cement bond log (CBL) — Wireline log evaluating cement bonding quality (indicator, not perfect).
  • Float collar / float shoe — One-way valves prevent backflow during cementing.
  • Liner — Casing string that does not reach surface (hung off inside previous casing).
  • Shoe track — Cement-filled section above float equipment.
  • Stage cementing — Cement placed in stages (stage tool) to manage ECD/weak zones.
  • TOC (Top of Cement) — Highest cement level in annulus after job.
  • Wait on cement (WOC) — Time for cement to set before drilling ahead.

F. Completions, stimulation, and production

  • Completion — Hardware/config enabling safe production/injection (tubing, packers, perforations, valves).
  • Christmas tree (XMT / XT) — Valve assembly at wellhead controlling flow.
  • Perforating — Creating holes through casing/cement into formation (guns, charges).
  • Perf density — Shots per foot/meter (SPF/SPM).
  • Packer — Downhole seal isolating annulus/tubing.
  • Frac / hydraulic fracturing — High-rate pumping to create fractures and boost permeability.
  • Proppant — Sand/ceramic to hold fractures open.
  • Acidizing — Acid pumped to dissolve damage or create wormholes in carbonate.
  • Flowback — Return of frac/kill fluids during cleanup.
  • Choke — Flow restriction controlling rate/pressure.
  • Artificial lift — Methods to lift fluids (ESP, gas lift, rod pump, PCP, plunger, jet pump).
  • ESP — Electrical submersible pump.
  • Gas lift — Inject gas to reduce fluid density and lift.
  • SRP (rod pump) — Sucker rod pump / beam pump system.
  • PCP — Progressing cavity pump.
  • Water cut — Fraction of produced fluids that is water.
  • GOR — Gas-oil ratio.
  • BS&W — Basic sediment and water (crude quality metric).

G. Workover and intervention

  • Coiled tubing (CT) — Continuous tubing for intervention/stimulation.
  • Snubbing — Running pipe under pressure with hydraulic unit.
  • Fishing — Recovering lost equipment (fish) from wellbore.
  • Mill-out — Milling plugs/packer parts (common after multi-stage frac).
  • P&A (Plug and abandon) — Permanent well abandonment with cement plugs and regulatory steps.
  • Scale / paraffin — Deposits restricting flow; require mechanical/chemical removal.

H. Mudlogging and wellsite geology (operations terms)

  • Mudlog — Real-time record integrating drilling parameters, cuttings description, and gas/fluorescence data.
  • Cuttings — Rock fragments carried to surface; described for lithology/indicators.
  • Lagged depth — Corrected depth of cuttings/gas after lag time.
  • Gas units / total gas — Relative gas detector response (system-specific calibration).
  • Connection gas — Gas spike associated with stopping/starting pumps at a connection.
  • Trip gas — Gas observed while tripping (often swabbing effects).
  • Background gas — Baseline gas level while drilling steady.
  • Shows — Hydrocarbon indicators (fluorescence, cut, odor, gas peaks, stain).
  • Fluorescence / cut — UV fluorescence and solvent “cut” behavior used to infer hydrocarbons.
  • Chromatograph (C1–C5) — Gas composition separation (methane through pentanes).
  • Caving vs drilled cuttings — Differentiating sloughed material from new lithology.

I. Geology, petrophysics, and reservoir

  • Anticline / fault trap / strat trap — Common hydrocarbon trap types.
  • Cap rock / seal — Low-permeability layer trapping hydrocarbons.
  • Facies — Depositional rock body characteristics (controls reservoir quality).
  • Net pay — Thickness meeting cutoffs (porosity, saturation, etc.) for producible interval.
  • Porosity (ϕ) — Fraction of rock volume that is pore space.
  • Permeability (k) — Ability of rock to transmit fluids.
  • Saturation (Sw/So/Sg) — Water/oil/gas fraction of pore volume.
  • OWC/GOC — Oil-water contact / gas-oil contact.
  • PVT — Pressure-volume-temperature fluid properties (reservoir engineering).
  • STOIIP / GIIP — Stock tank oil initially in place / gas initially in place.
  • Recovery factor — Produced fraction of hydrocarbons in place.
  • Decline curve — Production decline modeling (exponential/hyperbolic/harmonic).

J. Surface facilities, processing, and measurement

  • Separator (2-phase/3-phase) — Splits gas/oil/water using gravity and internals.
  • Heater treater — Heats crude to aid water separation.
  • Dehydration — Removing water from gas (glycol) or oil (treating).
  • Sweetening — Removing H₂S/CO₂ (amines, scavengers).
  • Flare — Controlled combustion of gas for safety/disposal.
  • LACT — Lease automatic custody transfer (metering skid for sales oil).
  • Pigging — Running pigs to clean/inspect pipelines.
  • SCADA — Supervisory control and data acquisition for remote monitoring/control.

K. Offshore and subsea (if you touch deepwater)

  • Riser — Conduit between subsea BOP and surface rig.
  • LMRP — Lower marine riser package (part of subsea BOP stack system).
  • EDP — Emergency disconnect package.
  • FPSO — Floating production storage and offloading vessel.
  • Umbilical — Hydraulic/chemical/electrical line bundle to subsea equipment.
  • Manifold — Subsea piping/valving assembly combining or distributing flows.
  • Subsea tree — Tree installed on seabed wellhead.

Oil & gas acronyms (high-coverage master list)

Acronyms collide a lot in oil & gas; many have multiple meanings depending on discipline. Here’s a broad, field-heavy list you’ll actually see (drilling, mudlogging, geology, completions, production, facilities, HSE).

A

  • AAPG — American Association of Petroleum Geologists
  • AFE — Authorization for Expenditure
  • API — American Petroleum Institute; API gravity (oil density scale)
  • AOFP — Annular operating friction pressure
  • AOR — Area of responsibility
  • AWT — Acid wash treatment

B

  • BHA — Bottomhole assembly
  • BHP — Bottomhole pressure
  • BHT — Bottomhole temperature
  • BOP — Blowout preventer
  • BPD — Barrels per day
  • bbl — Barrel
  • BS&W — Basic sediment and water
  • BTU — British thermal unit

C

  • C1–C5 — Methane through pentanes (mudlogging chromatography)
  • CBL — Cement bond log
  • CCL — Casing collar locator
  • CIP — Casing integrity pressure (context-dependent)
  • CO₂ — Carbon dioxide
  • CT — Coiled tubing
  • CWI — Certified welding inspector (often facilities)

D

  • D&C — Drilling & completions
  • DC — Drill collar
  • DLS — Dogleg severity
  • DM — Drilling mud (context)
  • DP — Drillpipe; differential pressure (context)
  • DPO — Daily progress (ops reporting)

E

  • ECD — Equivalent circulating density
  • EDP — Emergency disconnect package
  • EIA — Energy Information Administration
  • EOR — Enhanced oil recovery
  • ESP — Electrical submersible pump
  • ET — Environmental testing / elapsed time (context)

F

  • FAC — Flow assurance (context)
  • FCP — Final circulating pressure
  • FIT — Formation integrity test
  • FPSO — Floating production storage and offloading
  • FR — Field representative
  • FT — Flow test / formation tester (context)

G

  • GC — Gas chromatograph
  • GIIP — Gas initially in place
  • GL — Gas lift
  • GOR — Gas-oil ratio
  • GR — Gamma ray
  • GWD — Gas-water contact (sometimes GWC)

H

  • HAZID — Hazard identification
  • HAZOP — Hazard and operability study
  • H₂S — Hydrogen sulfide
  • HCl — Hydrochloric acid (acidizing)
  • HMI — Human-machine interface
  • HPHT — High pressure high temperature
  • HSE / HSEQ — Health, safety, environment (and quality)
  • HPU — Hydraulic power unit
  • HWDP — Heavy weight drillpipe

I

  • IA — Inhibitive additive (mud context)
  • IADC — International Association of Drilling Contractors
  • ID — Inside diameter
  • IFR — Incident frequency rate
  • IP — Initial production
  • IWCF — International Well Control Forum

J

  • JHA / JSA — Job hazard analysis / job safety analysis
  • JIP — Joint industry project

K

  • KB — Kelly bushing (reference elevation)
  • KOP — Kickoff point
  • KPI — Key performance indicator
  • KTB — Kick tolerance (sometimes KT)

L

  • LACT — Lease automatic custody transfer
  • LCM — Lost circulation material
  • LNG / LPG — Liquefied natural gas / liquefied petroleum gas
  • LOT — Leak-off test
  • LWD — Logging while drilling
  • LMRP — Lower marine riser package

M

  • MAASP — Maximum allowable annular surface pressure
  • MASP — Maximum allowable surface pressure
  • MD / TVD — Measured depth / true vertical depth
  • MIA — Material inventory accounting (facilities context)
  • MMSCFD — Million standard cubic feet per day
  • MSE — Mechanical specific energy
  • MW — Mud weight; molecular weight (context)
  • MWD — Measurement while drilling

N

  • NAF — Non-aqueous fluid
  • NPT — Non-productive time
  • NORM — Naturally occurring radioactive material

O

  • OB / O/B — Overburden
  • OBM — Oil-based muds
  • OCS — Outer continental shelf
  • OH — Open hole
  • OPEX / CAPEX — Operating / capital expenditures
  • OWC — Oil-water contact

P

  • P&A — Plug and abandon
  • PDC — Polycrystalline diamond compact (bit)
  • PFD / P&ID — Process flow diagram / piping & instrumentation diagram
  • PIT — Pit volume totalizer (mud system)
  • POOH / RIH — Pull out of hole / run in hole
  • PP — Pore pressure
  • PTW — Permit to work
  • PVT — Pressure-volume-temperature

Q

  • QA/QC — Quality assurance / quality control
  • QHSE — Quality, health, safety, environment

R

  • RFT / MDT — Repeat formation test / modular formation dynamics tester (formation pressure sampling tools; naming varies)
  • RKB — Rotary kelly bushing (elevation reference)
  • ROP — Rate of penetration
  • RSS — Rotary steerable system

S

  • SBM — Synthetic-based mud
  • SCADA — Supervisory control and data acquisition
  • SICP / SIDPP — Shut-in casing / drillpipe pressure
  • SPE — Society of Petroleum Engineers
  • SPWLA — Society of Petrophysicists and Well Log Analysts
  • SPF — Shots per foot (perforation density)
  • SPP — Standpipe pressure
  • SRP — Sucker rod pump
  • SSSV — Subsurface safety valve
  • STOIIP — Stock tank oil initially in place
  • SW — Water saturation (often Sw)

T

  • TD — Total depth
  • TDS — Total dissolved solids
  • THP / WHP — Tubinghead pressure / wellhead pressure
  • TOC — Top of cement
  • TRIR / LTIR — Total recordable / lost time incident rate
  • TVDSS — True vertical depth subsea

U

  • UWI — Unique well identifier
  • UV — Ultraviolet (fluorescence work)

V

  • VDL — Variable density log (cement evaluation context)
  • VSP — Vertical seismic profile

W

  • WBM — Water-based mud
  • WHP — Wellhead pressure
  • WOC — Wait on cement
  • WOB — Weight on bit
  • WOV — Workover
  • WT — Well test

X / Y / Z

  • XMT / XT — Christmas tree
  • YP — Yield point

If you want the “actually complete” version

If your goal is a true master reference (thousands of terms + thousands of acronyms), the best workflow is:

  1. Use the SLB Energy Glossary as the primary term dictionary (breadth + maintained).
  • Use IADC’s drilling acronym appendices for drilling-heavy abbreviations.
  • Use SPE/OnePetro E&P Glossary for upstream engineering + reservoir vocabulary.

If you tell me whether you want the deliverable as (a) a printable PDF, (b) an Excel/CSV, or (c) a web-page style glossary, I’ll format it accordingly and expand this into a much larger A–Z set (including log curve mnemonics, drilling report shorthand, mudlogger gas units conventions, and facilities/process acronyms).