Onshore oil and gas sector guidance

8. Flares at onshore oil and gas sites

Permitting of flares at onshore oil and gas sites, EU emissions trading system (ETS) and flares, and best available techniques (BAT) to design and operate the flaring system.

8.1 The purpose of your flare

Flares on onshore oil and gas sites must be regulated. For permitting, flares are classed as one of the following:

  • a waste incinerator – if you burn gas as a waste at any time
  • safety device – if you only use it as a safety flare during emergencies or maintenance work

Follow these guidelines to work out the purpose of your flare.

Flares used to burn gas as waste

If you are using a flare as part of well testing or workovers (for either oil or gas) and you intend to discard the gas, the flare’s purpose is classed as waste incineration.

Flares used for maintenance or safety

If you are capturing oil or gas as a commodity, and you only use flaring for maintenance or safety, the flare’s purpose is classed as a safety device.

Examples of using flares for safety purposes include:

  • in emergencies
  • over-pressure flaring
  • for maintenance - both scheduled and unscheduled maintenance of your primary gas management technique

You do not need to comply with emissions limits or controls on using the safety flare as the Environment Agency considers the health and safety of the workforce as paramount.

However, you will need to comply with conditions on monitoring and reporting on the use of your safety flare. These conditions will be in your permit and will include notifying the Environment Agency:

  • in advance if you plan to use the safety flare, giving the reasons for use
  • as soon as reasonably practical of any unplanned uses of the safety flare and reasons for use

You will also need to report on volume of gas burnt in the flare – calculated for each flaring event and on an annual basis.

You may need to keep CCTV records of the flare when it is in use.

Flares with a dual purpose

If you are using your flare to burn waste gas (because oil is the primary commodity) and act as safety device, it will be classed as a waste incinerator.

8.2 Permits for flares classified as waste incinerators

If the total capacity of all waste incineration flares on your site is more than 10 tonnes per day, you will need an installations permit to comply with the Industrial Emissions Directive (IED). This threshold is based on the rated capacity of the flare, regardless of the actual or expected amount of gas incinerated.

Below this threshold you need a mining waste permit to comply with the Mining Waste Directive.

In both cases, you will need to follow the BAT guidance on flaring systems.

8.3 Permits for flares classified as safety devices

The Environment Agency will regulate flares performing a safety role in these ways.

If your site already includes an IED installation, then safety flares will usually be regulated as a directly associated activity to the installation activity covered by your permit. For example, it could be associated to a refining activity or to the handling of crude oil.

Or the Environment Agency may decide to regulate the flare by incorporating a specific operating technique within the permit.

If your site does not include an IED activity, the Environment Agency will regulate your flare under the general management condition of your mining waste permit.

8.4 EU ETS

You may also need to apply for an EU ETS permit if the total of all combustion units on your site exceeds 20 megawatt thermal (MWth) or approximately 1.5 million standard cubic feet per day input.

For EU ETS, no distinction is made between the production and exploration phase because all flares (over the relevant thresholds) are captured by the EU ETS.

When initially calculating the total for your site, combustion units below 3 MWth input are not included. However, once you have exceeded the 20 MWth input limit, all combustion units regardless of rating will need to be included in the EU ETS permit.

Read the guidance on EU ETS permits.

8.5 Flaring systems BAT

You are expected to use BAT to prevent waste gas arising from your processes, or if this is not practicable, to reduce your emissions and impact on the environment. To determine BAT for your site, and demonstrate that you have considered all available options, you should use the methodology in the report Waste gas management at onshore oil and gas sites: framework for technique selection or an equivalent approach. This may result in using a combination of techniques, one of which may be a flaring system to combust any remaining gases.

The report shows that if flaring is assessed as the appropriate technology for treating any residual waste gases, indicative BAT is to flare the gas using an enclosed flare system. This generally provides the best environmental performance for incinerating waste gases.

An enclosed flare is characterised by the following features:

  • the burners are designed to operate within an enclosure
  • the enclosure is thermally insulated
  • there is a mechanism to control the combustion air feed rate to optimise combustion

We will consider other types of flaring system if you can provide a robust justification for using them based on the methodology in the report.

8.6 Designing the flaring system

You must describe the design of your flaring system in your permit application or as part of your pre-application submission of information.

Waste gas flow rate

Your flare design must show that it operates efficiently across the range of expected waste gas flow rates. Enclosed flares have a poor turndown efficiency, which means a large flare is inefficient when operated at low flow. For a wide flow range you may need to install either:

  • 2 flares, for high and low flow
  • a multiple burner flare, where the burners can be operated independently

Other design considerations

Your flare design must also consider:

  • stack height - to make sure exhaust gases are dispersed adequately
  • minimising noise, vibration and visual impact - especially for flares with a high flow rate
  • smoke - there must be no visible smoke from the flare, if smoking is likely you must include a smoke suppression system
  • duration of flaring
  • how you will manage sour gas and control odour
  • the ability to monitor combustion emissions

8.7 Operating the flaring system

In your permit application, you will need to provide information about how you will operate your flaring system. This must include information about the technically competent personnel you will employ to operate the flare. You will also need to provide descriptions of how you will:

  • manage the flare and waste gases if the flow rate exceeds or falls below the design flow range
  • extract the gas from the well - for example, by flow due to pressure within the well or by pumping
  • maintain the flare system

You must provide details of your proposals for continuous flame monitoring, including:

  • the ability to monitor combustion temperature
  • the ability to monitor feed gas flow continuously
  • main flame detection and auto-ignition
  • telemetry to alarm if the flare goes out

You should describe your monitoring protocol, which should include monitoring of the:

  • gas entering the flare
  • temperature of the flare

The Environment Agency may ask you to monitor combustion products. Though there may be instances when they do not require this. For example, due to the very short-term duration of flaring and the conditions at a particular site.