September 2011
Oil and Gas Commission Fact Sheet
www.bcogc.ca
Overview: Flaring & Venting at Facilities
The BC Oil and Gas Commission recognizes that flaring and incineration at petroleum industry facilities is a concern to British
Columbians. The Commission recently developed new flaring guidelines aimed at minimizing flared gas volumes resulting from
upstream petroleum industry activities, and continues to work with operators and members of the public in an effort to eliminate
or reduce flaring.
Facilities include wellsite facilities, oil batteries, compressor stations and gas processing plants. Flaring and venting sources at
facilities:
Continuous sources such as:
Intermittent sources such as:
• Sweetening systems
• Instrumentation
• Dehydrators
• Maintenance
• Production tanks
• Process upsets and emergencies
• Solution gas
• Purge and pilot gas
Sweetening Systems
Flaring of acid gas can be reduced or eliminated through the
Sweetening is a process used to remove hydrogen sulphide (H2S)
use of sulphur recovery or underground injection. Injection of
and carbon dioxide from raw natural gas. Collectively, carbon
sulphur scavengers at the well is being used increasingly to
dioxide and hydrogen sulphide are referred to as ‘acid gas’ due
remove low levels of hydrogen sulphide. The spent scavenger
to their corrosive nature when mixed with water. Sweetening
can then be removed by liquid separation at a facility.
occurs at a natural gas processing plant and involves the use of
a liquid contactor called an amine unit to absorb the acid gases.
Dehydrators
When the amine solution is regenerated, a concentrated stream
Dehydration is a process that removes water vapour from
of acid gas is produced.
natural gas. Dehydration may occur at a processing plant or at
a wellsite or compressor station. Dehydration is accomplished
Depending on the location and the quantity and composition
by one of two methods: adsorption of water on the surface of
of the acid gas stream, elemental sulphur may be recovered
solid dessicant beads or absorption in a glycol solution. Gycol is
by means of the Claus process, alternatively the acid gas may
a liquid that has a strong affinity for water.
be disposed of to a suitable underground formation such as a
depleted oil or gas reservoir or a saline reservoir, transported to
When glycol is used for dehydration, gas and liquid gycol are
another plant for further processing or flared and released to
brought into contact in a ‘glycol contactor’. Dry gas exits the
the atmosphere. Flaring is the least desirable option due to the
top of the contactor and wet glycol exits the bottom of the
resulting sulphur emissions.
contactor. The wet glycol is sent to a reboiler, which heats the
glycol and boils off the water, allowing the glycol to be reused.
igniters use sparks or heated elements to ensure ignition of any
Off gas from the reboiler includes water vapour and a small
gas that is released.
amount of methane and other hydrocarbons such as benzene.
Depending on the site, the off gas may be vented or flared.
Instrumentation
At small sites where compressed air is not available, natural gas
There are several strategies to reduce emissions from glycol
may be used to power pneumatic pumps and instrumentation.
dehydrators. Off gas may be flared instead of vented to reduce
The gas is then vented to atmosphere. The US EPA has reported
emissions of harmful hydrocarbons, operation of the dehydrator
that instrumentation is collectively one of the largest sources of
can be optimized to minimize the carryover of hydrocarbons
methane emissions is the natural gas industry.
from the contactor or a condenser may be used to condense the
water vapour and allow the residual methane to be recycled into
A variety of technologies have been developed in recent years to
the dehydrator inlet.
replace the use of natural gas in instrumentation. These include:
‘low bleed’ pneumatic devices that vent less gas and conversion
Production Tanks
to air powered instrumentation. Air powered instrumentation
Production tanks are used to store liquids such as crude oil,
requires a compressed air source. At smaller sites, solar power,
condensate (a low density, liquid hydrocarbon that is usually
thermoelectric generators or a turbines in the natural gas
produced with natural gas) and water. During storage, gas is
flowline may be used to power a compressor.
released from these tanks and may be vented, flared or recovered.
Maintenance
Methods to reduce flaring and venting from production tanks
Flaring during maintenance operations at facilities occurs any
include the use of pressurized tanks to reduce the release of
time equipment has to be depressured. Maintenance flaring is also
gas, flaring of the gas in place of venting or the use of a vapour
required to purge gas from vessels and piping so that they can be
recovery unit to capture and recycle the gas. Gas from production
worked on safely and to remove air and other contaminants prior
tanks is often contains heavier hydrocarbons ‘rich gas’ that are
to startup. As maintenance flaring is intermittent, opportunities
hard to combust. Incinerators usually are superior to flares for the
for reduction are limited.
combustion of rich gas streams.
Process Upsets and Emergencies
Purge and Pilot Gas
Process upsets occur when a process or equipment fails to
Purge gas is a continuous low flow of gas in a flare system that is
function as designed. At a processing plant, a process upset may
used to ensure that oxygen does not enter the flare system and
occur when a sweetening system fails to remove enough sulphur,
create an explosion hazard and to keep condensation out of the
creating ‘off-spec’ gas that cannot be sent to sales because it
flare system so that the flare lines are unobstructed in the event
contains too much sulphur. The ‘off-spec’ gas must be flared until
of an emergency. A facility can often be optimized to reduce the
the problem is fixed.
volume of purge gas. As purge gas is an important safety feature,
it cannot be completely eliminated.
Flaring resulting from process upsets can be reduced by
restricting or ceasing operations until the upset condition
Pilot gas is gas used to maintain a small flame at the top of a
has been resolved. Where process upsets become frequent,
flare stack. The pilot flame ensures that, in the event of a process
equipment or operational changes may be required.
upset, any gas released to the flare stack is combusted. This is an
important safety precaution that is used at sour gas facilities to
Energencies occur when there is a major failure such as a fire,
ensure that hydrogen sulphide is not released. Pilot gas can be
explosion or gas leak at a facility. In emergency situations, the
reduced by using flare pilot designs that use less pilot gas. Where
facility may be shut down and depressured to flare to ensure
safety allows, flare pilots can be replaced by auto-igniters. Auto-
safety. Emergency flares at facilities are uncommon and short in
duration.
Regulations
an effort to eliminate or reduce flaring. As a result, numerous
In 2008, the Commission released the Flaring, Incinerating
further incorporation of flaring and venting reduction options.
and Venting Reduction Guideline for British Columbia (Flaring
Guideline). With natural gas conservation a key objective,
the Guideline provides regulatory requirements for flaring,
engineering technologies and other provisions have allowed for
Where conservation is possible, the Commission’s ultimate goal
is to approve applications that conserve gas.
regulated under the Petroleum and Natural Gas Act and
Notifying Residents Prior to Flaring
or Incinerating
Pipeline Act in British Columbia. Guideline requirements
Prior to planned flaring or incineration (not including flaring
include:
as a result of an emergency), operators are required to provide
incinerating, and venting at any well site, facility and pipeline
24 hours’ advance notice to the Commission. All residents and
• Increased scrutiny of flare applications
• Economic assessments of associated (solution) gas flares
• Improvements to existing facilities
• Greater emphasis on design of new facilities to reduce
flaring
• Policy changes (e.g. temporary pipelines, flowlines to
unproven wells etc.)
In the year since the Guideline was brought into effect, the
Commission has worked with operators on production facility
administrators of incorporated centres must be notified when
flaring exceeds four hours duration or the gas rate exceeds a
set volume (30,000 m3/day). The notification radius is: 1 km for
sites where H2S is less than 1 per cent; 1.5 km for sites with H2S
is between 1 and 5 per cent; and 3 km for sites with H2S greater
than 5 per cent.
The Commission expects operators to provide an information
package to the public prior to planned flaring or incineration.
designs, ensuring all reasonable options are considered in
Complaints
Concerns raised by the public prior to flaring should be addressed by the operator. However, if outstanding concerns remain, the
operator or the public may request the Commission’s assistance. In situations where a flaring approval is not required and public
concerns have not been addressed by the operator, the public may make a complaint directly to the Commission. Commission staff
will respond to the complaint according to established procedures.
In cases where a member of the public has concerns about a specific flaring operation that is underway such as odours or excessive
noise, they should contact the Commission by calling the toll free incident reporting number at 1-800-663-3456.
Report a Concern/Learn More:
Tel: 1-250-794-5200 (24 hours a day)
24 Hour Main Switchboard:
To report concerns
regarding noise, smell or spill,
or for general information
24 Hour Emergency Response for
Industry Clients:
Fax: 1-250-794-5378
Web: www.bcogc.ca
Mail: PO Box 9331 Stn. Prov. Gov’t, Victoria, BC V8W 9N3
Toll free: 1-800-663-3456 (24 hours a day)