The use of technologies and operational practices to directly reduce emissions from oil and natural gas systems.

A facility that is actively processing or handling oil or natural gas fluid streams

The population of emitting equipment. For example, activity factor could refer to the mileage of natural gas pipeline, the count of thief hatches on a facility or the mechanical power of gas turbines.

The entity responsible for running a voluntary emissions reduction initiative and managing participation.

see: Alberta Energy Regulator (AER)

See: activity factor (AF)

Emissions data that has been collected from multiple sources and summarized, usually for the purpose of reporting or statistical analysis.

The regulatory body that oversees the development of oil, natural gas, oil sands, and coal resources in the province of Alberta, Canada.

see: Alternative Fugitive Emissions Management Program (alt-FEMP)

Innovative and science-based alternatives to fugitive emissions management programs (FEMPs). Alternative programs may incorporate the use of various LDAR technologies such as, unmanned aerial vehicles, vehicle-mounted sensors, and continuous monitoring devices to detect, track, repair, and report fugitive emissions. This term is used in Western Canada; in the U.S. and elsewhere, the term 'Alternative LDAR' is often used.

A discernible increase of a measured atmospheric gas over a baseline in which both the discernible increase and baseline are pre-defined. An anomaly occurs when the atmospheric concentration of a gas becomes larger than the minimum atmospheric concentration of that gas a technology can discern above noise. Not to be confused with detection.

Of, relating to, or resulting from the influence of human beings on nature. Source

Sweet or sour natural gas that is associated with the production of crude oil or crude bitumen. Often referred to as "solution gas", this gas evolves or "breaks out solution" from crude oil or crude bitumen under specific reservoir or production conditions.

A storage tank in which product is stored at ambient pressure. Atmospheric tanks are designed to operate at pressures less than 0.5 psig.

A remote emissions measurement technique. Downwind mixing ratios of a pollutant, geospatial data (e.g., source height and location), and environmental data (e.g., wind speed and direction) are used to infer the location and/or mass or volumetric flux of a source. Many approaches exist.

Audio, visual, and olfactory (AVO) is a methane detection survey performed using human senses. Regulations often have some form of AVO requirement that is equipment or site specific.

The verification of an organization's emissions data, practices, or performance by a third party.

Designed to enable verification of a organization's progress towards a goal or adherence to a voluntary initiative or regulation.

see: Audio, visual, and olfactory (AVO)

A voluntary initiative that incorporates compliance measures.

The release of gas from processing equipment or pipelines to the atmosphere in order to relieve pressure so that maintenance, testing or other activities can take place.

A list of emission sources by category and quantity. Often refers to an aggregate emission rate estimate achieved by multiplying activity factors (counts of components, equipment, or throughput) by emission factors (estimates of gas-loss rates per unit of activity). Most bottom-up inventories use emission factors derived from industry averages rather than measurements specific to the company. Bottom-up inventory emission rate estimates are consistently lower than site-level and regional emissions measurements in academic research.

Documentation of facility specific details, such as facility process operations, production, and emissions calculations used during a reporting period.

A measurement that occurs at a granular scale (e.g., component) that is used to estimate emissions more broadly. Bottom-up measurements are often averaged into emissions factors and combined with activity factors to build a bottom-up inventory.

The governing body that oversees oil and gas activities within the province of British Columbia, Canada.

The ratio of carbon emissions to some measure of productivity, such as natural gas production or energy content of oil.

A greenhouse gas trading system that enables monetisation of emissions reductions and/or strong performance relative to other market participants. Participants may buy or sell units of GHG emissions in order to operate within the limits outlined by the agreement governing a particular market.

A unit of greenhouse gas emissions reduced by one actor that can be traded to compensate for emissions by another actor.

A voluntary initiative that holds participants to binding standards that may include emissions reduction performance targets, use of specific technologies, and adoption of methodologies. Certifications entail an explicit declaration of achievement from the administering organization to the participant.

see: Comprehensive Monitoring Program

The chemical reaction where a hydrocarbon reacts with oxygen to create carbon dioxide, water, and heat. Energy is obtained from fossil fuels through combustion of the fuel. Source

How efficeintly a piece of equipment is burning a fuel. Combustion efficiency is an important consideration when estimating emissions, since combustion of natural gas destroys methane and creates carbon dioxide, which has a lower greenhouse potential. Higher combustion efficiencies will result in a higher degree of methane destruction and lower overall carbon intensity.

A voluntary initiative requiring participants to pledge efforts towards a goal that is decided upon by a governing body or collectively by participants within a group. Commitments are typically auditable, binding, and focus on achieving future goals.

The work incorporating the steps taken to transform a drilled well into a producing one. These steps include, but are not limited to: casing the well, cementing the casing, perforating the casing, installing down hole flow control or isolation equipment, hydraulic fracturing, and installing a well head with a production tree.

In emissions attribution, a component is the smallest scale of oil and gas infrastructure. Examples include valves, flanges, and threaded connections. Multiple components comprise equipment (e.g., tanks, separators) and a site may have multiple pieces of equipment or equipment groups.

A methane monitoring program that combines screening methods with close-range methods, to diagnose and precisely pinpoint leaking components.

Methane detection technology installed at a facility to provide repeated emissions measurements at high temporal resolution. Typical continuous measurement technologies may acquire measurements multiple times per second or multiple times per day.

Intentional releases of methane at a known location and rate used to test the performance of methane detection and quantification technology. Colorado State University's METEC facility is a well-known testing facility.

Emissions associated with a piece of equipment or facility under normal operations (operating at design conditions). Includes vented emissions and emissions from incomplete combustion.

A determination that a source may be present. Typically requires on analysis of one or a series of measured anomalies. Detections can be defined in terms of magnitude and/or duration of elevated mixing ratio or emission rate. For example, a detection event could be defined as an anomaly that reaches an estimated mass emission rate of 5 standard deviations above a 24-hour baseline Unlike an anomoly, a detection is intended to lead to a further action, e.g., follow-up and/or root-cause analysis.

The process of differentiating a product (typically natural gas) on the basis of some characteristic (typically a measure of carbon intensity or ESG performance).

The act of releasing private information to a target audience.

A measure of disclosure for voluntary initiatives introduced in Highwood's Voluntary Initiatives report.

Mathematicaly simulations that predict how a pollutant will move through the atmosphere.

The transportation of refined petroleum products from distribution hubs to the end users of these products.

The final stage in the oil and gas value chain. Activities include distribution, retail, marketing, product development, and consumption by the end user.

A representative value that attempts to relate the quantity of a pollutant released to the atmosphere with an activity associated with the release of that pollutant. These factors are usually expressed as the weight of a pollutant, divided by a unit weight, volume, distance, or duration of the activity emitting the pollutant (e.g., kilograms of particulate emitted per megagram of coal burned). Such factors facilitate an estimation of emissions from various sources of air pollution. In most cases, these factors are simply averages of all available data of acceptable quality, and are(...)

A measure of how quickly a pollutant is being introduced to the atmosphere. Typically expressed in either mass per unit time (e.g., kg/hr) or volume per unit time (e.g., SCF/hr). Many units exist and are used. To easily convert among them, try out Highwood's conversion tool, How Much Gas is That?!

Market-based instruments that create incentives to reduce emissions where these are most cost-effective. In most regulatory trading systems, the government sets an emissions cap in one or more sectors, and the entities that are covered are allowed to trade emissions permits. Rapid growth of voluntary ETSs is also underway. Source

A list of an organziation's emissions sources and their magnitude, which may be estimated using emissions factors, engineering estimates, measurement, or a combination.

A solution to a problem or difficult situation that relies on the application of math and science

A United States government agency whose work it is to improve society’s understanding of climate change and its impacts on human health and the environment. The data, tools, and resources that EPA develops can also be used by other agencies, organizations, states, tribes, and communities to help tackle the climate crisis effectively, equitably, and sustainably. Source

see: Environmental Protection Agency (EPA)

In emissions attribution, equipment is the second most granular piece of oil and gas infrastructure. Examples include tanks and separators. See definition of component for more details.

The concept that two LDAR programs mitigate equal amounts of emissions. In the context of LDAR programs, alternative work practices and technologies are required to demonstrate that they meet or exceed mitigated emissions under regulatory frameworks and voluntary initiatives (e.g., MiQ).

see: Environmental, Social, and Governance

see: emission trading system (ETS)

A permanently installed emissions monitoring system. See continuous measurement.

An intentional, controlled burning of natural gas that takes place during production and processing. Gas is ignited at the top of a flare stack, creating a characteristic flame. Source

Venting that occurs in a storage tank when the pressure of liquid with entrained gas drops and lighter compounds dissolved in the liquid are released/vented off.

An inspection to confirm or deny potential leaks detected during screening. Typically, a screening technology will identify a potential leak at the site or equipment-scale. Follow-up surveys diagnose leaks at the component scale, typically with handheld detection methods.  

The unintentional release of hydrocarbons to the atmosphere. Often referred to as leaks. Source

A program that is intended to complement a duty holder’s overall emissions reduction strategy by establishing a plan and supporting systems to systematically detect and manage fugitive emissions. This plan includes the systematic detection and repair of leaks, malfunctioning equipment, and surface casing vent flows. Detection of these leaks relies on regular surveys or screenings of sites for fugitive emissions. The term FEMP is characteristic of Western Canada. In the U.S. and elsewhere, the term 'LDAR Program' is often used. Source  | Source 2

The collection of petroleum products from their extraction point (wells), and their transport to a processing facility. A typical gathering system is highly branched, and consists of small-medium diameter pipelines with medium operating pressures.

The most commonly used dispersion model (see dispersion modeling). The Gaussian plume model is a relatively simple model (conceptually and computationally) that assumes the plume follows a normal (Gaussian) distribution in 3 dimensions.

see: greenhouse gas (GHG)

An emissions quantification framework that is widely used by businesses, industry associations, NGOs, and other organizations. Some initiatives use the GHG Protocol for their emissions quantification requirements. GHG protocol has published several standards but is recognized for these two emission quantification guidelines: (1) Corporate Standard – for scope 1, 2, and energy-related scope 3, and (2) Corporate Value Chain (Scope 3) Standard – for life-cycle emissions, both upstream and downstream

GWP was developed to allow comparisons of the global warming impacts of different gases. Specifically, it is a measure of how much energy the emissions of 1 ton of a gas will absorb over a given period of time, relative to the emissions of 1 ton of carbon dioxide (CO2). The larger the GWP, the more that a given gas warms the Earth compared to CO2 over that time period. The time period typically used for GWPs is 100 years. GWPs provide a common unit of measure, which allows analysts to add up emissions estimates of different gases (e.g., to compile a national GHG inventory), and allows(...)

see: Global Methane Initiative

A gas that traps heat in the atmosphere, such as carbon dioxide, methane, nitrous oxide, and fluorinated gases. Source

A set of frameworks, standards, principles, and/or tools designed to assist participants in meeting their goals and reporting on their progress

see: global warming potential (GWP)

A small, portable methane detection instrument that is often used to detect and diagnose leaks at the component scale. Examples include optical gas imaging (OGI) cameras and handheld organic vapour analyzers (OVAs).

A highly skewed probability distribution. Most emissions distributions are heavy-tailed, with a small number of super-emitters accounting for the majority of emissions.

The ability to safely tie into a pressurized system (e.g., pipeline, process piping, pressure vessels, etc.) by drilling or cutting into it while it is on stream and under pressure

A naturally occurring organic compound comprising hydrogen and carbon. Hydrocarbons can be as simple as methane [CH4], but many are highly complex molecules, and can occur as gases, liquids or solids. The molecules can have the shape of chains, branching chains, rings or other structures. Petroleum is a complex mixture of hydrocarbons. The most common hydrocarbons are natural gas, oil and coal. Source

Natural gas fuel not combusted by an engine or flare. Incomplete combustion increases carbon intensity because methane has a higher GWP than carbon dioxide.

Air that is used to supply pneumatic devices.

Natural gas that is used to supply pneumatic devices.

see: lifecycle analysis

see: leak detection and repair (LDAR) program

The combination of an LDAQ technology, a work practice, and analytics for use in an LDAR program. An LDAQ method must clearly state any mandatory actions to be performed as part of the work practice, along with suitable operating conditions for the technology. These can include environmental conditions, limitations on facility types, technology configurations, and survey procedure. Source

The systematic implementation of one or more LDAQ methods across a collection of assets. The program describes the method, or combination of methods, to be used for each facility, along with survey frequency, repair response, and reporting standards. Ultimately, it is the LDAR program that results in emissions mitigation, not the technologies or methods in isolation.  Source

 An open-source modeling framework for exploring the effectiveness of methane leak detection programs. The purpose of LDAR-Sim is to enable transparent, collaborative, flexible, and intuitive investigation of emerging LDAR technologies, methods, work practices, regulations, and deployment strategies. Learn more here.

A gas sensing instrument, optionally configured with a deployment platform and/or  ancillary  instruments  (e.g.  anemometers, positioning),  that  can  be  used  to  gather  data  on emissions.  Source

The unintentional release of hydrocarbons to the atmosphere. Often referred to as fugitive emissions. Source

Leak Detection and Repair is a work practice designed to identify leaking equipment so that emissions can be reduced through repairs. A component that is subject to LDAR requirements must be monitored at specified, regular intervals to determine whether or not it is leaking. Any leaking component must then be repaired or replaced within a specified time frame. Source

A distribution of leak rates for a group of sources. Leak-size distributions are often heavy-tailed, with a small number of large sources accounting for most emissions.

A technique for assessing the environmental aspects associated with a product over its life cycle. Source

Natural gas that has been cooled down to liquid form for ease and safety of non-pressurized storage or transport

see: liquified natural gas

Identifying the physical location of a leak source. Localization can be done at different scales (site-level, equipment-level and component-level).

Acquiring emissions data directly from the environment at a specific place and time.

A colourless, odourless gas that occurs abundantly in nature and as a product of certain human activities. Methane is the simplest member of the paraffin series of hydrocarbons and is among the most potent of the greenhouse gases. Its chemical formula is CH4. Source

Uncombusted fuel that passes through an engine.

A term referring to a stage in the oil and gas value chain following production and preceding distribution. Activities include processing, pipeline transportation, refining and storage.

The smallest atmospheric concentration or emission rate that a measurement method capable of discerning above background. Probability of detection is a preferred concept because the minimum is context dependent.

The amount that emissions are reduced below a baseline.

At its eighth session, the Conference of the Parties (COP), the decision-making body responsible for monitoring and reviewing the implementation of the United Nations Framework Convention on Climate Change, requested the secretariat to publish on its website the annual inventory submissions consisting of the national inventory report (NIR) and common reporting format (CRF) of all Parties included in Annex I to the Convention. The NIRs contain detailed descriptive and numerical information and the CRF tables contain all greenhouse gas (GHG) emissions and removals, implied emission(...)

Natural gas is a naturally occurring and flammable hydrocarbon gas that is used for fuel. Its primary component is methane, but it can also contain ethane, propane, butane, and pentanes. Often, impurities including oxygen, hydrogen sulfide (H2S), nitrogen, water, and carbon dioxide (CO2) are also present.

Achieving a state where either (1) no greenhouse gases are emitted, or (2) remaining emissions are offset through other actions or technologies that remove carbon from the atmosphere.

Upset, emergency, or intermittent venting of hydrocarbon emissions. This could include emergency process evacuation events.

A CEO-led initiative that aims to accelerate the industry response to climate change. OGCI member companies explicitly support the Paris Agreement and its aims. Source

A Climate and Clean Air Coalition initiative led by the UN Environment Programme, in partnership with the European Commission, the UK Government, the Environmental Defense Fund, and leading oil and gas companies. Source

A common leak detection approach that uses thermal infrared cameras to visualize methane and various other organic gases. Common OGI cameras create images of a narrow range of the mid-IR spectrum (3.2− 3.4 μm wavelength) which methane and other light hydrocarbons actively absorb.

EPA OTM 33A uses fast response instruments mounted on ground-based vehicles for the geospatial measurement of air pollution (GMAP) near the driving route. Typically, the vehicle remains stationary for an extended period of time as the methane plume washes over it. Location and source emission rate are estimated. Source

A quantifiable metric describing an LDAR method's performance. Ideally, performance metrics are constrained with independent, single-blind controlled release testing. The most important performance metric is probability of detection which is commonly expressed as a probability curve or surface. Many other performance metrics exist, including localization and quantification uncertainty, false positive rate, and more.

A body of one fluid (natural gas/methane) moving through another (ambient air).

Pneumatic controllers are a type of pneumatic instrument used on oil and gas sites. They control conditions such as temperature, pressure, and fluid levels. Source

Oilfield equipment powered through pressurized gas (either air or natural gas). They are frequently used when there is no electricity available on a site, and are a known source of methane emissions. Pneumatic instruments are often designed to vent gas with every cycle of their operation, referred to as "bleeding". Source

Pneumatic pumps are a type of pneumatic instrument. They are used to inject chemicals (such as methanol) into wells and pipelines, or circulate fluids. Source

A pressure relief valve (PRV) is a safety mechanism used to help regulate the pressure in a system. Pressure relief valves are a leading cause of emissions from hydrocarbon storage tanks. As the pressure in these tanks rises, the valve may open, releasing pressure, and in turn, releasing natural gas into the atmosphere. In this sense, PRVs are a source of venting.

see: pressure relief valve

The probability that a given emission source will be detected by an LDAR method. Probability of detection is often depicted as a sigmoid curve or surface, where it is the function of emission rate and other relevant variables (e.g., wind speed).

A general term for characterizing emissions numerically. Can be with emission factor bottom-up inventories or based on measurement. With measurement it often refers to emission rate estimation, but atmospheric mixing ratios may also be quantified.

Combines optical gas imaging (OGI) camera technology with cross-section pixel absorption algorithms to quantify emissions. The brightness of each pixel seen through the OGI camera is proportional to the amount of infrared radiation incident on the camera along the corresponding line of sight through the plume. The brightness is converted to a concentration and combined with estimated velocities to obtain mass fluxes. Source

Greenhouse gas emissions can be estimated using emissions factors, measurements, or engineering equations at various spatial and temporal scales. Reconciliation explores whether and why different estimation approaches vary. In some cases, reconciliation can be defined as a methodology for combining multiple different estimates into a single stronger estimate.

The process by which soil contaminants are managed and removed, and the site is readied for reclamation. In Alberta, this is done following AER and AEP requirements. Contaminated soil may be hauled to a landfill and then replaced with clean soil, or may be treated onsite until it meets AEP guidelines. Source

Routine venting refers to the intentional release of natural gas into the atmosphere from oil and natural gas equipment. This equipment includes (but is not limited to) pneumatic devices, glycol dehydrators, compressor seals, casing vents, and atmospheric tanks. Source

Scope 1 or direct emissions are those emissions arising from sources owned or controlled by an organization within a defined boundary. Scope 2 emissions are indirect emissions from the generation of purchased energy, from a utility provider. Scope 3 emissions are all indirect emissions – not included in scope 2 – that occur in the value chain of the reporting company, including both upstream and downstream emissions.

LDAR screening methods are used to rapidly flag high-emitting sites to direct close-range follow-up source diagnosis and root cause analysis. An example of a common screening method is an aerial monitoring campaign.

see: surface casing vent flow (SCVF)

Vessel used for separating a well stream into gaseous and liquid components

An uncharacteristically large point source of methane. Given that most methane emissions distributions are heavily skewed, a small number of super-emitters can account for the majority of aggregate emissions across the supply chain. Emissions distributions vary widely by basin and production type, so there is some debate over what constitutes a super-emitter. Highwood defines a super-emitter as any emission even with mass flux rate that exceeds 10 kg/h methane and an ultra-emitter as any source above 100 kg/h .

A condition where fluid or gas is flowing from the surface casing vent assembly. This term is typically used in conjunction with land wells. Source

The Technology Innovation and Emissions Reduction Regulation requires regulated facilities to reduce greenhouse gas emissions. The regulation applies to facilities which emit more than 100,000 tonnes of carbon dioxide. Facilities which emit less than the threshold may opt-in to the regulation, and conventional oil and gas facilities under the same ownership may be combined into a single aggregate facility. The regulation sets out high-performance benchmarks or enables the director to set facility-specific product benchmarks. To meet the emissions reduction requirement, facilities can(...)

The United Nations body for assessing the science related to climate change. It was created to provide policymakers with regular scientific assessments on climate change, its implications and potential future risks, as well as to put forward adaptation and mitigation options. Source

An aperture in a tank or vessel that may be open or closed. They are typically used on low pressure tanks. Thief hatches that have been left open can be a significant source of fugitive emissions. Source

see: Technology Innovation and Emissions Reduction Regulation

An emissions measurement that aggregates multiple potential sources into a single estimate. Top-down measurements may be equipment scale (consisting of multiple components), site level (consisting of all equipment groups on site), or regional (consisting of all sites in a measurement area). See bottom-up measurement.

The transportation of petroleum products from processing facilities to distribution hubs. Transmission systems consist of large-diameter, high-pressure pipelines that transport high volumes of petroleum products across large distances.

The degree to which an initiative or producer discloses their internal operations and standards and allows for accessibility of information regarding an initiative.

The TROPOspheric Monitoring Instrument (TROPOMI) is the gas-sensing instrument on the Copernicus Sentinel-5 Precursor satellite developed by the European Space Agency. TROPOMI has been used to identify methane ultra-emitters around the world.

see: unmanned aerial vehicle

 A large super-emitter that emits at least 100 kg/h methane.

Unconventional resources are hydrocarbon-bearing units where the permeability and porosity are so low that the resource cannot be extracted economically through a vertical well bore and instead required a horizontal well bore followed by multistage hydraulic fracturing to achieve economic production. Source

A term that refers to the exploration and production processes within the oil and gas value chain. Activities include drilling, infrastructure development and production.

A system composed of a scrubber, a compressor, and a switch. Its main purpose is to recover vapors formed inside completely sealed crude oil or condensate tanks. The switch detects pressure variations inside the tanks and turns the compressor on and off. The vapors are sucked through a scrubber, where the liquid trapped is returned to the liquid pipeline system or to the tanks, and the vapor recovered is pumped into gas lines. Source

The controlled release of unburned gases into the atmosphere, such as natural gas or other hydrocarbon vapours, water vapour, or other gases. Source

A coordinated effort managed by an administering organization that enables participants to take standardized voluntary steps towards targeting, achieving, and/or taking credit for emissions reductions.