Oil & Gas Industry Terms & Definitions

The oil and gas industry is filled with technical terminology, standards, and acronyms that can be confusing to those outside the field. Whether you’re an engineer, safety manager, or procurement officer, understanding this jargon is critical for compliance, safety, and efficient operations.

This glossary defines the most essential terms in the oil and gas industry, from workplace safety agencies to engineering specifications, providing a clear, professional resource for industry professionals.

Why These Terms Are Important

A

Acidizing: A well stimulation technique where acid is injected into the reservoir rock to dissolve minerals, increase permeability, and improve hydrocarbon flow.

ADA (Americans with Disabilities Act): A U.S. civil rights law that prohibits discrimination based on disability, including provisions that affect the design of industrial and commercial buildings to accommodate individuals with disabilities.

AHJ / LAHJ (Authority Having Jurisdiction / Local Authority Having Jurisdiction): The organization, office, or individual with legal authority to enforce building, safety, electrical, or environmental codes. Responsibilities vary by location and type of facility.

American Petroleum Institute (API): A U.S. trade association that sets technical and safety standards for the oil and natural gas industry. API standards are widely referenced in regulations and industry practice.

Anchorage System: Structural components used to secure a building or module to its foundation or supporting surface so that it can resist the required loads and movement.

API RP 752: An American Petroleum Institute recommended practice addressing management of hazards associated with the location of permanent buildings in process plants.

API RP 753: An American Petroleum Institute recommended practice addressing management of hazards associated with the location of portable buildings in process plants.

API RP 756: An American Petroleum Institute recommended practice addressing management of hazards associated with the location of tents in process plants.

ASCE (American Society of Civil Engineers): A professional body that develops civil engineering standards, including those relevant to building response levels for hazardous areas.

B

Barrel of Oil Equivalent (BOE): A unit of energy used to combine oil and gas volumes into a common measure. One BOE represents the energy released by burning one barrel of crude oil.

Blast / Blast Event: Refers to an explosion at a petrochemical, refining, or industrial facility, which causes overpressure and potential structural, human, and asset damage.

Blast Overpressure: Pressure above normal atmospheric pressure created by a blast wave. Peak overpressure and the duration of the pressure loading are important considerations in blast-resistant design.

Blast-Resistant Module (BRM): A structure engineered to mitigate the effects of explosions and protect occupants. BRMs are used in industrial, military, or high-risk environments. Hunter Onsite offers single modules, multi-unit complexes, and specialty units. Also often referred to as blast-resistant buildings (BRBs).

Blowout Preventer (BOP): A high-pressure safety device installed on the wellhead during drilling. It is used to seal, control, and monitor well pressure to prevent uncontrolled release of oil or gas (“blowouts”).

Bottom-Hole Pressure (BHP): The pressure at the bottom of the wellbore, often in the reservoir. Critical for evaluating reservoir behavior and well design.

Building Siting Evaluation: An assessment of whether occupied structures are appropriately located in relation to potential explosion, fire, and toxic-release hazards.

Bunker: In industry jargon, either a reinforced shelter or a large container for storing fuel. Often used in contexts of safety or logistics.

C

Casing: Steel pipe installed in a drilled well, then cemented in place to stabilize the wellbore, protect freshwater zones, and isolate different pressure formations.

Cat Cracker (FCCU – Fluid Catalytic Cracking Unit): Refinery equipment that breaks down heavy hydrocarbon molecules into more valuable, lighter products like LPG and gasoline. Also relevant in facility siting due to risks and required protection.

CEC (Canadian Electrical Code): A standard developed by CSA that governs the installation and maintenance of electrical equipment in Canada.

Class I, Division 1: A hazardous location where ignitable concentrations of flammable gases or vapors may exist during normal operations, may occur frequently during maintenance or leakage, or may be released by equipment failure.

Class I, Division 2: A hazardous location where flammable liquids, gases, or vapors are normally confined within closed systems but may be released because of accidental rupture, equipment failure, or abnormal operation.

Classified Area: A location in an industrial facility where hazard levels involving fire or explosion require special electrical, equipment, design, or material standards.

Completion: The process of preparing a well after drilling so that production of oil and/or gas can begin. Includes installation of permanently placed equipment.

Condensate: Hydrocarbon liquids, or light oils, recovered from natural gas when it cools and pressure is reduced. Often called natural gasoline or distillate.

Consequence-Based Approach: A facility-siting method that evaluates the potential effects of credible explosion, fire, or toxic-release scenarios without assigning a probability to each event.

Crude Oil: Unrefined petroleum extracted from the earth. Composed of hydrocarbons, which are refined into fuels, chemicals, and other end products.

CSA (Canadian Standards Association): A standards organization in Canada that develops and certifies technical, safety, and environmental standards. Widely used in oil & gas, building, and electrical codes.

D

Downstream: The segment of the oil and gas industry involving refining, processing, distribution, marketing, and sale of petroleum products to end users.

Dry Hole: A drilled well that does not produce oil or gas in economically viable quantities.

E

EOR (Enhanced Oil Recovery): Techniques used to extract more oil from a field after primary and secondary recovery. Methods include gas injection, thermal heating, chemical flooding, etc.

EPA (Environmental Protection Agency): A U.S. federal agency focused on protecting human health and the environment via regulation, research, and enforcement involving air, water, land, and chemicals.

F

FEA (Finite Element Analysis): A computational method used in engineering to simulate how structures, components, or systems respond to forces, stresses, heat, or other physical effects. Useful in designing blast-resistant buildings or modules to optimize structural integrity.

FRP (Fiberglass Reinforced Panel): A composite material consisting of a polymer matrix reinforced with fiberglass. It is used in environments demanding durability, corrosion resistance, and easy cleaning, often in wall panels and facades.

FSS (Facility Siting Study): An analysis, often consequence-based, evaluating potential fire, explosion, or toxic-release impacts for a facility. It helps determine safe distances, building ratings, and mitigation strategies.

G

Gas Lift: A method of artificially lifting fluids in a well by injecting gas into the tubing. This reduces hydrostatic pressure so fluids can be produced more easily.

GOR (Gas-Oil Ratio): The ratio of the volume of gas produced relative to oil from a production stream. High GORs can affect production economics and processing requirements.

H

HAZOP (Hazard and Operability Study): A structured review used to identify potential process hazards and operating problems by examining deviations from intended design or operation.

Horizontal Drilling: A drilling technique where the well is deviated from vertical into a horizontal segment within the reservoir to increase contact with the producing formation. Widely used in unconventional plays.

Hydraulic Fracturing (“Fracking”): A stimulation process involving the high-pressure injection of fluid and proppant into rock to create fractures and increase permeability. Critical for many shale and tight formations.

I

IBC (International Building Code): A model building code used widely in the U.S., developed by the International Code Council, defining minimum design and construction standards for structures, including safety, fire protection, and egress.

Impulse: A measure of blast loading that accounts for both pressure and the time over which that pressure acts. Pressure and impulse together help define a blast load.

Injection Well: A well used to inject fluid, such as water, gas, or steam, into a reservoir to maintain pressure or dispose of produced water.

Intumescent Coating: A coating that swells when exposed to high heat, providing fire resistance by forming an insulating char layer that protects structural elements.

ISO 9001: An international standard defining requirements for a quality management system (QMS). Demonstrates an organization’s ability to consistently provide products or services that meet customer and regulatory requirements.

J

Jet Fire: A type of flame resulting from the combustion of pressurized fuel, often in the form of a directed jet. Highly dangerous due to its impingement and radiant heat effects.

L

Leasing / Leasehold: Legal agreements granting rights to explore for, drill, or produce oil and gas on land or offshore for a defined period and under specified conditions. Includes primary and secondary lease terms.

LEL (Lower Explosive Limit): The lowest concentration of vapor or gas capable of igniting in the presence of an ignition source. Many hazardous-area standards use LEL to determine safety zones.

M

MCC (Motor Control Center): A centralized location where control and protection of multiple electric motors is managed via starters, panels, and controllers. Critical in ensuring safe power distribution.

Midstream: The segment of the oil and gas industry involving transportation, including pipelines and shipping, storage, and wholesale marketing of crude or processed resources between upstream production and downstream refining and distribution.

MSA (Master Service Agreement): A contract between parties outlining the terms, conditions, and standards under which future services or transactions will be performed. Reduces negotiation time per job.

MSDS / SDS (Material Safety Data Sheet / Safety Data Sheet): Documents providing information about hazards, handling, storage, and emergency protocols for chemical substances or products used in operations.

N

NDE / NDT (Non-Destructive Examination / Testing): Methods for testing materials or components without damaging them, such as ultrasound, X-ray, or magnetic particle testing. Used for quality assurance and safety inspections.

NEC (National Electrical Code): The U.S. standard for safe electrical design, installation, and inspection; analogous to Canada’s CEC. It is critical for electrical equipment sizing, wiring, and conduit in hazardous or classified areas.

O

Occupied Building: A building in which personnel are present for work, meetings, breaks, control activities, or other functions. Occupancy is an important consideration in process-plant facility siting.

OSHA (Occupational Safety and Health Administration): The U.S. agency responsible for ensuring safe and healthy working conditions through enforcement of safety standards, inspections, training, and workplace regulation.

P

Passive Fire Protection: Building components such as walls, doors, and floors, or materials designed to contain or slow fire spread without active systems such as alarms or sprinklers. Often required in classified or hazardous areas.

PFD (Process Flow Diagram): A schematic showing the general flow of plant processes, indicating major equipment and flow paths. Helps explain process sequences without full instrumentation detail.

P&ID (Piping & Instrumentation Diagram): A detailed diagram of piping, valves, instrumentation, control systems, and safety interlocks in a process plant. More detailed than a PFD.

PHA (Process Hazard Analysis): A systematic assessment used to identify, evaluate, and control hazards associated with industrial processes involving hazardous chemicals.

Pool Fire: A fire where fuel, as a liquid, pools on a surface or layer and burns, often producing intense heat. Important in hazard assessments and facility siting.

Porosity: The measure of empty spaces in rock, expressed as a percentage, that can store hydrocarbons. High porosity is essential for good reservoir performance.

Portable Building: A building designed so that it can be transported and repositioned. In process plants, its location and occupancy may need to be evaluated against explosion, fire, and toxic-release hazards.

Positive-Pressure Ventilation: A ventilation arrangement that maintains interior air pressure above the surrounding atmosphere to help limit infiltration of hazardous gases or vapors.

Process Safety Management (PSM): A systematic approach to managing hazards associated with processes involving highly hazardous chemicals.

Production Logging: Monitoring and measuring fluid production involving oil, gas, and water within the wellbore to assess performance and diagnose issues.

PSI (Pounds per Square Inch): A unit of pressure measuring force per square inch. Used in many oil and gas applications, including pipeline pressure, blast doors, and well-control systems.

Q

QRA (Quantitative Risk Analysis): A structured risk-based approach to identifying, quantifying, and ranking risks involving fire, explosion, and toxic release. It often includes or overlaps with a facility siting study.

R

Redundant System: A setup in which components are duplicated so that if one fails, another continues. Used in safety and mission-critical systems.

Reservoir: A subsurface, porous, and permeable rock formation that contains recoverable quantities of oil and/or natural gas.

Response Level: A measure of the expected damage and rescue or repair requirements after a blast event. Buildings with low response levels are preferred in hazardous zones.

Risk-Based Approach: A decision-making method that considers both the probability of a hazardous event and its potential consequences.

RP (Recommended Practice): A guideline document published by organizations, such as API RP 752/753, that describes best practices and procedures and is often referenced by regulators and facility designers.

S

Safe Haven: A location or structure designed to provide protection during disaster or explosion events. Often reinforced or shelter-like.

Separation (Oil-Gas-Water Separator): A facility or device that separates produced fluids into oil, gas, and water streams for further processing, treatment, or disposal.

Shelter in Place: A safety strategy in which people remain in their current location during an emergency rather than evacuating. The building must meet the protective requirements established for the applicable hazard.

Single Degree of Freedom (SDOF): A simplified analytical model used to estimate how a structural component responds over time to dynamic loading, including blast pressure and impulse.

Standoff Distance: The distance between a building or other protected asset and a potential explosion source. Blast effects generally decrease as standoff distance increases.

T

TA (Turnaround): A scheduled shutdown of production or operations, typically in a refinery or petrochemical plant, to perform maintenance, inspection, or upgrade work.

TDLR (Texas Department of Licensing and Regulation): A Texas state government agency overseeing licensing and regulation of occupations, facilities, and equipment, including building and safety codes.

Toxic Shelter: An occupied building or designated protective space intended to limit occupant exposure to an accidental toxic-material release through siting, sealing, ventilation controls, or other protective measures.

U

Upstream: The segment of the oil and gas industry involving exploration, drilling, development, and production of crude oil and natural gas.

V

VCE (Vapor Cloud Explosion): An explosion arising when a large cloud of flammable vapor, gas, or mist ignites, producing overpressure capable of causing structural damage.

W

Wellhead: The surface termination of a wellbore that provides pressure control, access for production, and connection to flow equipment. Includes valves and fittings to regulate flow and ensure safety.

Workover: Operations performed on a producing well to restore or increase production. May include cleaning, repair, stimulation, or recompleting the reservoir.

Z

Zone (Hazardous Area Classification): A method used to classify areas by explosion risk based on the presence and duration of flammable vapor or gas. Common in marine, petrochemical, and refinery settings.