900 Oil and Gas Safety Management

Glossary

A

Abandoning Wells. The controlled process of safely decommissioning an oil or gas well that is no longer productive or economically viable. This involves isolating the well with cement plugs, removing equipment, and sealing the borehole to prevent fluid migration or contamination of groundwater. Proper abandonment minimizes environmental impact and aligns with regulatory standards to ensure site safety.
Acute Toxicity. Refers to the harmful effects that manifest after a short-term exposure to a substance, typically within 24 hours or a few days. Acute toxicity often involves immediate, severe health effects such as organ failure, respiratory distress, or even death.
American Petroleum Institute (API). The primary trade organization for the oil and gas industry in the United States. API develops standards, guidelines, and certifications for equipment, operational safety, and environmental protection, ensuring industry-wide consistency and reliability. API’s standards are widely used worldwide to promote safety and efficiency across drilling, production, and refining activities.
Appearance (physical state, color, etc.). Describes the physical characteristics of a chemical, such as its state (solid, liquid, gas) and its color, which can be indicators of the purity or condition of the substance. This information helps users recognize the material and detect any changes that may indicate contamination or deterioration.
Auto-ignition Temperature. The lowest temperature at which a substance will spontaneously ignite without the presence of an ignition source. This property is critical for assessing fire risk during the storage and handling of chemicals. Substances with low auto-ignition temperatures may require special precautions to prevent accidental fires.

B

Bioaccumulation. The process by which a chemical substance increases in concentration in the tissues of living organisms over time, often because it is absorbed faster than it is metabolized or excreted. Bioaccumulative substances can pose long-term environmental and health risks.
Blowout Preventer (BOP). A vital mechanical device installed on top of oil and gas wells, primarily designed to control the well's pressure and prevent blowouts, which are uncontrolled releases of oil, gas, or drilling fluids. BOP systems consist of various components, including annular and ram preventers, which can seal the well in the event of a sudden pressure surge. These systems are mandatory on all high-pressure drilling rigs, both onshore and offshore, to protect workers, prevent environmental spills, and safeguard equipment. Proper maintenance, regular testing, and specialized training on BOP operation are essential for ensuring readiness and reliability in emergency situations.
Coiled Tubing Unit. A mobile piece of equipment that uses a continuous, flexible steel tubing coiled on a reel, which can be inserted into wells for interventions without requiring the well to be shut down. Common applications include well cleanouts, acidizing, fracturing, and chemical treatments. Coiled tubing units are widely used because they reduce downtime and allow for quick entry and exit of the tubing, enhancing well servicing efficiency.
Boiling Point. The temperature at which a liquid turns into vapor. The boiling point of a substance is important for determining its volatility and handling conditions. Substances with lower boiling points may evaporate quickly and require special storage or containment.

C

Carcinogenicity. The ability or tendency of a substance to cause cancer. Carcinogens may induce cancer by causing mutations in DNA or by disrupting cellular processes such as growth regulation and cell division.
CAS Number (Chemical Abstracts Service Number). A unique numerical identifier assigned to every chemical substance described in open scientific literature. CAS numbers are used globally to provide a consistent and unambiguous way to reference a specific chemical.
Caught-Between Accident. A hazardous incident that occurs when a worker is trapped between two objects, such as machinery parts, equipment, or structural elements. This type of accident often results in severe crushing injuries. To prevent these incidents, it is crucial to have adequate spacing around equipment, maintain clear communication, and follow lockout/tagout procedures when maintaining or repairing equipment.
Caught-In Accident. An accident in which a worker becomes entangled in moving machinery or equipment, leading to serious injuries, such as amputations or fractures. Prevention measures include the use of protective guards on machinery, adherence to lockout/tagout practices, and worker training on equipment handling.
Choke Manifold. A system of adjustable valves, chokes, and gauges that control well pressure and flow during drilling or well testing operations. The choke manifold allows operators to release or control the flow of fluids from the wellbore to maintain balance, stabilize pressure, and avoid blowouts. It is particularly important during drilling in high-pressure formations where controlled flow is essential for safety.
Chronic Toxicity. Refers to the adverse health effects that develop after long-term or repeated exposure to a hazardous substance, often over months or years. Chronic toxicity is typically associated with low-level, continuous exposure to chemicals that may accumulate in the body or cause damage over time.
Classification. The systematic process of identifying and categorizing chemicals based on their potential hazards, as defined by criteria set forth in the GHS. This classification process considers various hazards, including health hazards, physical hazards, and environmental hazards.
Confined Space. A work area not intended for continuous occupancy with restricted access and potential hazards. Examples in the oil and gas industry include storage tanks, silos, process vessels, and underground vaults. Confined spaces can have hazardous atmospheres due to toxic gases, limited oxygen, or combustible dust, posing significant risks.
Contractor Coordination. The process of managing and organizing contractors working on an oil or gas site to ensure alignment with safety protocols, work schedules, and responsibilities. Effective contractor coordination involves pre-job meetings, hazard communication, and continuous oversight to prevent conflicts and ensure that all contractors follow regulatory and operational standards.
Control of Hazardous Energy (Lockout/Tagout). OSHA regulations aimed at preventing accidental release of hazardous energy—such as electrical, hydraulic, or pneumatic power—during servicing or maintenance of equipment. Lockout/Tagout (LOTO) requires locking equipment switches in the “off” position and tagging them with a visible warning to prevent activation until maintenance is complete. In oil and gas operations, LOTO is critical for equipment like pumps, compressors, and drilling machinery, where unexpected start-ups could cause injuries or fatalities. Properly implementing LOTO also involves training personnel, inspecting equipment, and maintaining clear procedures to protect workers in proximity to energized equipment.
Crush Accident. A serious incident in which a worker is crushed by equipment, vehicles, or structural elements, often resulting in severe injuries or fatalities. Crush accidents are common in environments where heavy machinery is operated. Preventative measures include situational awareness training, machine guarding, and strict adherence to equipment operation guidelines.

D

Deck. A horizontal working area, typically on offshore platforms, where equipment, personnel, and transport operations are managed. Decks are built to withstand significant loads and are often equipped with non-slip surfaces, guardrails, and designated zones to prevent accidents and ensure worker safety.
Decomposition Temperature. The temperature at which a chemical substance breaks down into simpler substances or releases gases, often with the potential for hazardous reactions. This property is critical for assessing safety in situations where chemicals are exposed to high temperatures.
Degasser. A device that removes entrained gases, such as hydrogen sulfide (H₂S) or methane, from drilling mud. This equipment prevents potentially hazardous gas buildup in the drilling fluid, reducing the risk of blowouts and maintaining fluid density. Degassers are essential for safety in drilling operations, particularly in areas where gas "kicks" are common.
Dermal Exposure. Contact between a chemical substance and the skin, which may lead to absorption into the body. Dermal exposure can result in localized effects like irritation or burns, or systemic effects if the substance is absorbed into the bloodstream.
Derrick. The tall, load-bearing structure on an oil or gas drilling rig that supports the hoisting and rotating systems necessary for drilling deep wells. Derricks are built to support heavy equipment, including drill pipes and drill strings, and to allow for the safe lifting and lowering of these components. Modern derricks are designed to endure high wind loads and harsh conditions, especially on offshore rigs.
Drill Bit. The cutting tool attached to the end of the drill string that physically breaks rock formations to create the wellbore. Drill bits come in various types, such as roller-cone, polycrystalline diamond compact (PDC), and fixed-cutter bits, each suited for specific rock types and drilling speeds. Choosing the correct drill bit type is crucial for efficient drilling, cost management, and minimizing wear on equipment.
Drilling Fluid (Mud). A specially engineered fluid that plays a key role in drilling operations, serving to cool and lubricate the drill bit, lift cuttings to the surface, stabilize the borehole, and maintain well pressure. There are several types of drilling fluids, including water-based, oil-based, and synthetic-based mud, each selected based on specific subsurface conditions. In addition to enhancing drilling performance, these fluids help manage formation pressures, preventing blowouts. The environmental impact of drilling muds, particularly those used offshore, is a concern, so formulations are often designed for minimal toxicity, and disposal is strictly regulated.
Drill Pipe. A heavy-duty, hollow steel pipe used to transmit rotary torque and drilling fluids from the surface to the drill bit. Drill pipes are essential for creating deep wellbores, as they withstand high pressures, axial loads, and abrasive environments. Drill pipe is manufactured in multiple lengths and diameters to accommodate the depth and conditions of each drilling project.

E

Electric Submersible Pump (ESP). A downhole pump installed inside the well casing to lift oil to the surface when reservoir pressure is too low for natural flow. ESPs consist of a multi-stage centrifugal pump, an electric motor, and a power cable. They are highly efficient in lifting large volumes of fluids from deep wells, making them ideal for artificial lift in mature or low-pressure wells.
Frac Pump. A high-powered pump used to inject hydraulic fracturing fluids at extremely high pressures into a wellbore to create fractures in the surrounding rock formation. These fractures allow oil or gas to flow more freely to the wellbore. Frac pumps are engineered to withstand high stress and are often operated in fleets during large-scale hydraulic fracturing operations.
Emergency Response Plan (ERP). A structured plan outlining procedures to manage various emergency situations, such as fires, hazardous chemical spills, explosions, and natural disasters. In the oil and gas industry, ERP includes detailed steps for evacuation, spill containment, medical emergencies, and communications. OSHA mandates that ERPs are customized to address site-specific risks, are accessible to all employees, and involve regular training and drills to ensure workers are prepared.
Emergency Shutdown (ESD). A critical safety system designed to stop operations immediately in the event of an emergency, such as a fire, gas leak, or equipment failure. ESDs are equipped with triggers and sensors to automatically halt processes to protect workers and the environment. Regular testing and maintenance of ESD systems are essential to ensure they function effectively when needed.
Engineering Controls. Safety measures that eliminate or reduce hazards through the design of equipment, processes, or systems. Examples include using guards on rotating machinery, installing ventilation systems to control hazardous vapors, and adding sensors to monitor gas leaks. Engineering controls are prioritized in the hierarchy of controls as they do not rely on worker behavior.
Evaporation Rate. The rate at which a substance transitions from a liquid to a vapor at room temperature. It is typically compared to the evaporation rate of a reference substance such as ethyl ether. The evaporation rate helps assess how quickly a substance can become airborne, which is important for understanding fire hazards and exposure risks.
Explosive. Refers to a chemical that can undergo a violent reaction when exposed to certain conditions, such as heat, pressure, friction, or a spark, leading to the release of gas and heat, which may cause significant damage.

F

Fall-from-Above Accident. An incident in which a worker falls from an elevated area, such as scaffolding, ladders, or elevated platforms. Prevention methods include the use of personal fall arrest systems (PFAS), guardrails, and safe ladder practices. Regular safety inspections and training on fall prevention are critical to reducing these types of accidents.
Fall-to-Surface Accident. An accident in which a worker falls onto a ground-level surface, often resulting from slips, trips, or loss of balance. Prevention strategies include wearing appropriate footwear, using anti-slip floor coatings, and ensuring walkways are clear of hazards. Training on fall prevention is also essential for reducing these incidents.
Flammable Range. The range of concentrations of a gas or vapor in air between the lower flammability limit (LFL) and upper flammability limit (UFL) in which an explosion can occur if an ignition source is present. Outside this range, the gas or vapor will not ignite.
Flammability (solid, gas). The ability of a solid or gas to ignite and burn under specific conditions. Flammable solids or gases can pose serious fire hazards in industrial or laboratory settings and are classified based on how easily they ignite.
Flash Point. The lowest temperature at which a liquid gives off enough vapor to form an ignitable mixture with air. It is a critical indicator of a liquid's flammability risk. Substances with lower flash points ignite more easily, requiring careful handling to avoid accidental fires.
Flowline. A pipeline that transports produced fluids (oil, gas, or water) from the wellhead to processing facilities or storage tanks. Flowlines are designed to handle high pressures and harsh environmental conditions. They are an integral part of the production process, connecting various pieces of equipment, such as separators, treaters, and storage tanks.

G

Gap Analysis. A structured process used to identify the differences between current practices or performance and desired standards or outcomes. In oil and gas, gap analyses are used to improve safety protocols, identify training needs, and update operational procedures to meet regulatory requirements and industry best practices.
GHS (Globally Harmonized System). A worldwide standard for classifying and labeling hazardous chemicals. The GHS system aims to improve safety by providing consistent criteria for identifying hazards, labeling products, and communicating risks through Safety Data Sheets (SDS).
Gas. A state of matter in which a substance has neither a definite shape nor volume and can expand to fill any space. Gases may pose inhalation hazards, and some are flammable or reactive, requiring careful handling and containment.

H

Hazard Communication (HAZCOM). An OSHA standard that requires employers to communicate information about hazardous chemicals used in the workplace. This involves labeling chemicals, providing Safety Data Sheets (SDS), and ensuring that workers are trained on the risks, proper handling, and emergency response for each chemical. In the oil and gas industry, HAZCOM is essential due to the routine handling of potentially dangerous substances like drilling fluids, acids, solvents, and gases.
Hazardous Chemical. Any chemical that poses a risk to health, safety, or the environment. This includes chemicals that are toxic, corrosive, flammable, explosive, or reactive, as well as those that pose environmental hazards such as aquatic toxicity.
Hazard Statement. A phrase that describes the nature and degree of the hazard posed by a chemical, as standardized by the GHS. Hazard statements are included on chemical labels and in Safety Data Sheets (SDS) to ensure that users understand the risks associated with handling a substance.
Hierarchy of Controls. A framework used to prioritize safety interventions and reduce or eliminate workplace hazards. The hierarchy is organized as follows: Elimination (removing the hazard entirely), Substitution (replacing the hazard with a safer alternative), Engineering Controls (design changes to isolate people from the hazard), Administrative Controls (modifying work practices), and Personal Protective Equipment (PPE) as the last line of defense. This hierarchy helps guide safety decisions and minimizes reliance on worker behavior alone for safety.

I

Inhalation. The process of breathing in gases, vapors, dust, or fumes, which can lead to exposure to harmful chemicals. Inhalation is one of the primary routes of exposure to hazardous substances, and depending on the chemical, it can cause immediate or long-term health effects.
Initial Boiling Point & Boiling Range. The temperature at which a liquid first begins to boil (initial boiling point) and the range of temperatures over which the liquid continues to boil. These properties are important for understanding the volatility of a substance and its potential to become airborne or cause pressure buildup in containers.
Interim Measures. Temporary safety measures or modifications used to manage a hazard until a permanent solution is implemented. These may include installing temporary barriers, restricting access, or issuing additional PPE. Interim measures ensure continued safety during the process of addressing or mitigating identified hazards.
Isolation. The practice of segregating hazards or energy sources to prevent unauthorized access and ensure worker safety. Common isolation techniques include Lockout/Tagout (LOTO) for machinery and physical barriers for areas containing hazardous materials. Isolation is a fundamental step in reducing accident risks during maintenance and repair activities.

J

Job Safety Analysis (JSA). Also known as Job Hazard Analysis (JHA), JSA is a structured process used to identify and mitigate potential hazards associated with specific job tasks. During JSA, each step of a job is evaluated for potential risks, and control measures are implemented to reduce those risks. In the oil and gas industry, JSAs are commonly used for high-risk activities such as rigging, lifting, and drilling.
Joule (J). The SI unit of energy, often used to describe the energy released or absorbed during chemical reactions. Understanding the energy involved in a reaction can help assess its potential hazards, such as explosive or exothermic reactions.

K

Kelly. A square or hexagonal-shaped, rotating section of the drill string that connects to the rotary table, allowing it to transfer rotary motion to the drill bit. The Kelly is a key part of rotary drilling rigs and provides continuous torque, enabling the bit to penetrate rock. It is designed to withstand substantial pressure and weight during drilling operations.
Kinematic Viscosity. The measure of a fluid's resistance to flow under the influence of gravity, typically expressed in units of centistokes (cSt). Kinematic viscosity is crucial for determining how fluids behave in various systems, such as pipelines or engines.

L

Labeling. The process of attaching or printing a label on a chemical container to communicate hazards and instructions for safe use, in compliance with the GHS system. Labels must include hazard symbols, signal words, and hazard and precautionary statements.
LD50 (Lethal Dose 50). The dose of a substance that causes the death of 50% of a test population, typically animals, in toxicology studies. LD50 is an important measure of acute toxicity and helps classify chemicals under the GHS.
Lower Explosive Limit (LEL). The lowest concentration of a gas or vapor in air that can produce an explosion if an ignition source is present. Below this concentration, the mixture is too lean to ignite.

M

Manlift. A powered platform used to lift workers to elevated areas for tasks such as inspection, repair, or construction. Manlifts are commonly found on oil rigs, refineries, and drilling sites. Safety features include harness attachment points, emergency stop controls, and guardrails. Operators must receive specific training to operate manlifts safely.
Melting/Freezing Point. The temperature at which a solid substance melts to become a liquid (melting point) or a liquid solidifies to become a solid (freezing point). Knowing these points is essential for determining how a substance will behave under various temperature conditions, particularly in storage or transport.
Mud Pump. A heavy-duty, high-pressure pump used to circulate drilling mud through the drill string and back up the annulus. Mud pumps help maintain hydrostatic pressure in the well, preventing blowouts and stabilizing the wellbore. Mud pumps are essential for safe and efficient drilling operations, particularly in deep wells.
Mutagenicity. The property of a chemical substance that causes genetic mutations, which are permanent changes in the DNA of an organism. Mutagens can damage genes and increase the risk of diseases such as cancer or genetic disorders.

N

Needs Assessment. A systematic approach to identifying the specific safety and operational requirements of a project or site. Needs assessments are essential in oil and gas operations to determine resources, training, equipment, and policies necessary to achieve safe and effective operations. This process aligns with risk management and regulatory compliance goals.
NFPA Rating (National Fire Protection Association Rating). A standardized system for identifying the hazards of materials during emergency situations, particularly fires. The NFPA rating system uses a diamond-shaped label with four color-coded sections to rate the health hazard, flammability, reactivity, and special hazards of a substance.

O

Odor. The characteristic smell of a chemical, which can serve as an initial indicator of the presence of certain hazardous chemicals. Odor can sometimes signal a gas leak or dangerous vapor release, but not all hazardous substances produce a noticeable odor.
Odor Threshold. The lowest concentration of a chemical at which its odor becomes detectable. This value is important for identifying substances in the air, but caution is required as some chemicals can be harmful even at concentrations below their odor threshold.
Oil and Gas Extraction. The series of processes used to locate, drill, and recover oil and natural gas from beneath the earth's surface. This phase includes seismic surveys, exploratory drilling, and production. Extraction processes involve heavy machinery, high-pressure systems, and require adherence to strict safety and environmental protocols.
Oil and Gas Servicing. The suite of activities performed on a well after it has been drilled, including well workovers, equipment maintenance, and performance enhancement techniques. Servicing improves efficiency, maintains safety standards, and ensures equipment integrity. Specialized equipment and trained personnel are required for servicing activities to ensure safety and reliability.
Operating Procedures. Detailed, documented instructions outlining the steps necessary to complete tasks safely and effectively. In oil and gas, operating procedures cover activities such as drilling, well servicing, and emergency response, ensuring that tasks are conducted consistently and in compliance with safety standards.

P

Partition Coefficient: n-octanol/water. A measure of a substance's tendency to partition between a hydrophobic solvent (like octanol) and water. It indicates how soluble a substance is in fats compared to water, which can be useful for predicting how the substance will distribute in the environment or in biological systems.
Perforating Gun. A device loaded with explosive charges, used to create openings in the well casing or liner during well completion. These openings allow oil or gas to flow from the reservoir into the wellbore. Perforating guns can be deployed on wireline or coiled tubing, and they are engineered to produce consistent, high-precision perforations.
Personal Protective Equipment (PPE). Equipment worn by workers to protect against specific hazards. In the oil and gas industry, PPE commonly includes hard hats, safety goggles, flame-resistant clothing, gloves, and respiratory protection. The selection of PPE is based on a hazard assessment to address risks such as chemical exposure, falls, or high temperatures. Employers are responsible for providing PPE and training workers in its use and maintenance.
pH. A measure of the acidity or basicity of a solution, with values ranging from 0 to 14. A pH of 7 is neutral, values below 7 are acidic, and values above 7 are basic. The pH of a substance is critical for understanding its potential to cause skin or eye irritation, corrosion, or reactions with other materials.
Pictogram. A graphical symbol used in the GHS system to visually communicate specific types of hazards associated with chemicals. These pictograms are printed on labels and Safety Data Sheets (SDS) and are recognized globally.
Platform. A large, stable structure, often used offshore, that houses equipment, drilling rigs, and accommodations for workers. Platforms are designed to endure harsh marine environments and support significant operational loads. Common types include fixed, floating, and tension-leg platforms.
Plugging Wells. The process of permanently sealing a well that is no longer active to prevent fluid migration or contamination. This involves setting cement plugs along the wellbore to isolate zones and stabilize the site. Proper plugging protects groundwater, surface ecosystems, and ensures regulatory compliance.
Precautionary Statement. A phrase included on GHS labels and Safety Data Sheets (SDS) that describes measures to take to prevent or minimize exposure to hazardous chemicals. These statements may relate to prevention, response, storage, or disposal of hazardous chemicals.
Process Safety Management (PSM). An OSHA regulatory framework that aims to prevent accidents involving hazardous chemicals by implementing rigorous safety protocols. PSM requires employers to develop and follow management systems covering process design, equipment integrity, operating procedures, and emergency preparedness. In the oil and gas industry, PSM is essential in areas with high potential for chemical releases, such as refineries, processing plants, and storage facilities.
Production Tubing. A string of pipe placed inside a completed well to facilitate the controlled flow of hydrocarbons from the reservoir to the surface. Production tubing is designed for easy removal, enabling routine maintenance and interventions. It protects the well casing from produced fluids and ensures efficient resource extraction.

Q

Quenching. A process used to stop or slow down a chemical reaction, often by cooling or adding a reactive substance that neutralizes the active species. Quenching is important in controlling reactions that might otherwise become hazardous.

R

Reactivity. Describes the tendency of a chemical to undergo a chemical reaction with other substances or conditions, such as heat, pressure, or exposure to water or air. Highly reactive substances can explode, emit toxic gases, or catch fire under certain conditions.
Relative Density. The ratio of the density of a substance compared to the density of water. It helps determine whether a liquid will float or sink in water, which is essential for understanding its behavior in spills or environmental releases.
Rigging. The practice of preparing heavy loads for lifting and moving, often using slings, chains, ropes, and specialized lifting devices. Rigging is critical in drilling operations for tasks such as transporting pipes, equipment, and materials. Proper rigging techniques prevent accidents by ensuring that loads are balanced, supported, and moved safely. OSHA regulations for rigging include guidelines for equipment inspection, load weight limits, and worker qualifications, as improper rigging can lead to serious injuries, property damage, or fatalities.
Risk Assessment (RA). A systematic evaluation of potential hazards associated with specific activities or equipment. In oil and gas, RAs identify risks related to pressure systems, chemicals, and machinery. RAs guide decisions about control measures, PPE, and operational adjustments to reduce incident likelihood.
Rotary Table. A rotating platform located on the drill floor that provides torque to the drill string through the kelly. The rotary table turns the drill bit, allowing it to penetrate rock. It is a key component of traditional drilling rigs and provides continuous and controlled rotation to the drill pipe.

S

Safety Data Sheet (SDS). A document required for any chemical considered hazardous, providing information about the substance’s properties, health hazards, safe handling, and emergency measures. SDSs are a key component of OSHA's HAZCOM standard, and every worker must have access to them. In the oil and gas industry, SDSs are used for chemicals like drilling mud additives, cleaning agents, and lubricants. An SDS outlines first aid measures, firefighting instructions, and environmental precautions, helping workers make informed decisions about safe chemical use and response in case of spills or exposure.
Separator. A large, pressure-resistant vessel that separates produced fluids into oil, gas, and water streams. Separators are critical for initial processing, as they prevent excess water or gas from entering pipelines and enable further refining of hydrocarbons. They are configured to handle high volumes and pressures, often at both onshore and offshore facilities.
Shale Shaker. A vibrating screening device used in the initial phase of solids control, which separates cuttings and large particles from drilling mud. Shale shakers ensure that drilling fluids can be recycled by removing solids before re-circulation, increasing drilling efficiency and reducing waste.
Signal Word. A word used on GHS labels to indicate the relative severity of a chemical's hazard. The two signal words are "Danger" for more severe hazards and "Warning" for less severe hazards.
Site Preparation. Preliminary work done to ready a location for drilling or production, including soil stabilization, land clearing, and setting up essential infrastructure. Site preparation minimizes environmental disruption and enhances worker safety. Proper planning ensures efficient and environmentally compliant operations.
Snubbing Unit. A specialized hydraulic rig that allows for the insertion or removal of pipe from a well under pressure, without having to kill (stop) the well. Snubbing units are essential for high-pressure wells, as they enable safe well interventions and workover operations without interrupting production.
Solubility(ies). Refers to the ability of a substance to dissolve in a solvent, typically water. The solubility of a chemical can influence how it behaves in the environment, how it is handled, and how it can be safely disposed of. Substances that are highly soluble in water may pose greater risks of contamination in aquatic environments.
STOT (Specific Target Organ Toxicity). Refers to chemicals that have toxic effects on specific organs or systems in the body after either a single exposure (STOT-SE) or repeated exposure (STOT-RE). These substances can cause damage to organs such as the liver, kidneys, lungs, or central nervous system.
Struck-By Accident. An incident in which a worker is hit by moving vehicles, falling objects, or other moving equipment. Preventive measures include using barricades, wearing hard hats, and ensuring controlled equipment operation. Struck-by accidents are a leading cause of injuries on oil and gas sites.
Struck-Against Accident. An accident in which a worker accidentally collides with equipment, machinery, or structural elements, often resulting in bruising or fractures. Prevention includes clear signage, adequate lighting, and safe placement of equipment to reduce collision risks.
Substitution. A method within the hierarchy of controls where a hazardous substance or process is replaced with a less hazardous alternative. In oil and gas, substitution can mean using less volatile chemicals or switching to safer equipment, minimizing exposure risks.
Supplier Identification. Information that identifies the manufacturer, importer, or distributor of a chemical product. Supplier identification typically includes the company name, address, and contact details. This information is required on both the chemical label and the Safety Data Sheet (SDS) to ensure that users can contact the supplier if more information is needed or in case of emergency.
Swivel. A mechanical device that connects the hook to the drill string, allowing the drill pipe to rotate while maintaining fluid connections. The swivel prevents twisting of the drill string and reduces stress on the equipment, making it a crucial component for smooth and efficient drilling operations.

T

Teratogenicity. The ability of a chemical substance to cause developmental malformations or defects in an embryo or fetus when a pregnant woman is exposed to it. Teratogens can interfere with the normal development of an embryo, potentially leading to birth defects or pregnancy complications.
Top Drive. A motor-driven device mounted on the drilling mast, used to rotate the drill string from above. Top drives replace the rotary table and Kelly, providing greater control and efficiency. They enable continuous drilling, reduce manual handling of heavy equipment, and increase safety by minimizing exposure to moving parts.

U

UN Number (United Nations Number). A four-digit identification code assigned by the United Nations Committee of Experts on the Transport of Dangerous Goods to identify hazardous substances or articles. UN numbers are used internationally in shipping and handling to ensure that hazardous materials are properly classified, labeled, and transported.
Upper/Lower Flammability or Explosive Limits. The range of concentrations of a vapor or gas in air that will ignite or explode if exposed to an ignition source. The lower explosive limit (LEL) is the minimum concentration required to support combustion, while the upper explosive limit (UEL) is the maximum concentration above which combustion cannot occur due to insufficient oxygen.

V

Vapor Density. The density of a vapor in relation to the density of air. Vapor density helps predict how a vapor will behave in the air, whether it will rise or settle. Vapors denser than air tend to settle near the ground, increasing the risk of exposure or fire in confined spaces.
Vapor Pressure. The pressure exerted by the vapor of a liquid or solid at a given temperature when the substance is in equilibrium with its vapor phase. High vapor pressure indicates a substance will readily evaporate into the air, potentially posing an inhalation hazard.
Viscosity. A measure of a fluid's resistance to flow. Substances with high viscosity, like honey, flow more slowly than those with low viscosity, like water. Viscosity is important for understanding how a substance behaves in pipes, machinery, or during application processes.

W

Warnings. Signals or notices, such as alarms, signs, and labels, used to alert workers of potential hazards. Warnings are part of administrative controls and are essential for informing workers of risks and necessary precautions in high-risk areas.
Water Reactivity. The tendency of a substance to react with water, often releasing hazardous gases or heat. Water-reactive chemicals, such as sodium or calcium carbide, require special storage and handling to prevent accidental contact with water.
Well Completion. The process of making a drilled well ready for production by installing casing, tubing, and other necessary components. Completion may involve well stimulation techniques, such as hydraulic fracturing or acidizing, to increase flow. Proper completion ensures well integrity and maximizes resource extraction.
Well Control. Techniques and equipment used to maintain control of well pressure to prevent the unintended release of oil, gas, or fluids. Core well control measures include using drilling fluids to balance formation pressure, implementing blowout preventers (BOPs), and monitoring for pressure anomalies. In oil and gas, well control is paramount to prevent blowouts and ensure safety. Training in well control includes emergency shutdown procedures and is critical for all personnel involved in drilling, completion, and well intervention operations.
Wellhead. The assembly of components at the surface of the well that provides the structural and pressure-containing interface for drilling and production equipment. A wellhead includes casings, tubing hangers, valves, and chokes, which allow for control over the well and containment of high pressures during extraction. Wellheads are designed for durability and to withstand harsh environmental conditions.
Wireline. A steel cable used to lower and retrieve tools into the wellbore for logging, perforating, or well intervention activities. Wireline operations are crucial for gathering data, such as formation pressures, temperature, and fluid samples, to assess the well’s condition and enhance production. Wirelines are also used to deploy specialized tools for maintenance and repairs.
Work Practices. The methods and procedures workers follow to perform tasks safely, including correct lifting techniques, proper PPE usage, and adherence to safety protocols. Work practices are part of administrative controls and are critical to minimizing risks in hazardous environments.
Workover Operations. Maintenance and repair procedures conducted on an existing well to restore or enhance its production. Common workover activities include replacing damaged tubing, clearing blockages, and performing recompletion or hydraulic fracturing. Workover operations are complex and involve heavy equipment, chemical handling, and pressure control, requiring specialized safety protocols. OSHA mandates safety measures for workover operations to mitigate risks associated with confined spaces, high-pressure systems, and chemical exposures, making worker training and safety planning essential.
Workplace Exposure Limit (WEL). The maximum allowable concentration of a hazardous substance in the workplace air for a specified period. WELs are designed to protect workers from the harmful effects of long-term exposure to chemicals.

X

Xylene. A common solvent derived from petroleum, used in the manufacture of paints, varnishes, and other industrial products. Xylene is flammable and can pose health risks if inhaled or ingested in large amounts, requiring proper ventilation and protective equipment.

Y

Yield Stress. The amount of stress required to cause a material to deform permanently. Yield stress is important in understanding the mechanical properties of materials and their ability to withstand stress without breaking.

Z

Zero VOC (Volatile Organic Compound). Refers to products or materials that contain no or very low amounts of volatile organic compounds, which are chemicals that can easily evaporate into the air and contribute to air pollution and health issues.
Zone Isolation. The technique of sealing off different sections (zones) within a wellbore to prevent fluids from one zone from mixing with others. In oil and gas, zone isolation is achieved using barriers like cement, casing, or mechanical packers to contain fluids and avoid cross-contamination, which can impact reservoir integrity and production. This process is essential in well completion, production, and abandonment stages to prevent unintentional releases, safeguard the environment, and ensure the structural integrity of the well.