What is Flaring?
Flaring is the burning of natural gas that cannot be processed or sold. Flaring
disposes of the gas while releasing emissions into the atmosphere. Most flaring
performed in Western Canada involves "sweet gas" which is natural gas
containing little or no Hydrogen Sulphide (H2S).
Flaring is also used to dispose
of sour gas containing H2S and waste gas containing contaminants such as H2S and
Carbon Dioxide (CO2). It is a very important safety measure at natural gas
facilities as it safely disposes of gas during emergencies, power failures, equipment
failures or other "upsets" in the processing. Regulators have established
guidelines for flaring reduction. Flare reduction increases the amount of marketable
product being recovered and sold while also reducing emissions to the atmosphere.
Where does Flaring take Place?
Flares are used in various types of operations at thousands of locations throughout
British Columbia, Alberta and Saskatchewan. These operation types include:
1) Solution Gas Flaring
Natural gas contained in crude oil is called "solution gas". Flaring
is used to dispose of natural gas produced along with crude oil and bitumen.
If at all possible, this gas is recovered and pipelined to a processing facility.
When oil is underground, the pressure of the reservoir holds gas in the oil
and the pressure is reduced when the oil comes to the surface. This occurs at
facilities called "batteries" where production from one or more wells
is produced and stored.
2) Gas Plant Flaring
Gas processing plants remove the water, H2S, CO2 and
natural gas liquids from the raw natural gas to produce the market-ready natural
gas. Flares are used to dispose of the unmarketable gases. All gas plants have
flares to burn off gas safely during emergencies or "upset" conditions
that interrupt the normal day-to-day operations. Many of the small plants are
licensed to flare H2S rich gas after it has been removed.
3) Well Test Flaring
Well test flaring occurs during drilling and testing of all oil and gas wells.
This is a standard practice used to determine the types of fluids the well can
produce, the pressure and flow rates of fluids and other characteristics of
the underground reservoir. If there are pipelines nearby, operators may be able
to direct the test gas to a processing plant and this process is called "in-line
testing". This is not a practice that is feasible for some exploratory
wells as there may not be any pipelines and processing plants nearby. The pressure,
flow and composition of the gas has to be determined before it can be safely
handled by the pipelines and processing plants. This information determines
the economic value of the well and what type of production facilities will be
installed. Also, additional flaring during "under balanced drilling"
operations is performed to dispose of the gas that comes to the surface. This
process speeds up drilling and reduces the damage to producing formations by
the drilling fluids. Some well test flaring may be necessary after certain well
servicing operations. The average flaring duration is 2.5 days.
4) Natural Gas Battery and Pipeline Flaring
This type of flaring can occur at producing field facilities such as wells,
dehydrators, compressors and gathering pipelines. Flares burn off gas during
emergencies, maintenance shutdowns, equipment failures and other upset conditions.
Why do Natural Gas Facilities have Flare Stacks?
Flare stacks are primarily a safety measure to prevent the accumulation of
gases that could pose a hazard. They are particularly important at sour gas
facilities because H2S is flammable, toxic and slightly heavier than air. Combustion
converts H2S into Sulphur Dioxide (SO2) which can be toxic but it is lifted
by the hot plume of gases and dispersed into the atmosphere. The amount of SO2
which is released into the atmosphere is regulated under provincial air quality
What is Emitted from the Flares?
It has been assumed that flares burn at 99% efficiency. However,1% of incomplete
combustion can produce Carbon Monoxide (CO), unburned hydrocarbons, particulate
matter (soot and ash), volatile organic compounds (Benzene, Toluene, Xylene),
other organic compounds known as Polycyclic aromatic hydrocarbons and small
quantities of Sulphur compounds such as Carbon Disulphide (CS2) and Carbonyl
Sulphide (COS). Benzene is known as a cancer causing compound and Carbon Disulphide
is also classified as a poison affecting the central nervous system. The effects
of these depend on the magnitude, duration and frequency of exposure. Many of
these compounds are not unique to flaring and are common products of incomplete
combustion in emissions from automobiles, forest fires, stubble burning, barbecues
1) Greenhouse Gases
CO2 is a greenhouse gas that may affect the global climate.
Methane (CH4), the main component of natural gas, is more than 20 times
as potent per kilogram as CO2. Flaring methane produces fewer net greenhouse
gas emissions than would result from just releasing the natural gas. Some Nitrogen
Oxides are potent greenhouse gases.
2) Acid Disposition
Nitrogen and Sulphur Oxides may combine with water in the atmosphere to form
acids. These are eventually deposited on the earth's surface. Flaring
and incineration account for the majority of upstream Sulphur Oxide emissions
and a significant portion of the Nitrogen Oxides. Emissions may fall rapidly
or be carried for many kilometers before being deposited. The amount of acid
disposition to any given area depends on the height of the flare or incinerator
stack, the wind and its direction and the precipitation patterns. In most sour
gas producing areas, soils are resistant to acidification because they contain
a lot of fine particles (mainly, clay and silt). In Alberta, the dry climate
and the amount of alkaline dust in the air also moderates the impact of SO2
This material was obtained from AER and Petroleum Communication Foundation