Sable Island - the Offshore Energy Industry

(September 2002,  Revised March 2004)

The Venture location, in May 1999, seen from the eastern tip of Sable Island. 

In spring and autumn large numbers of Common and Arctic terns roost on the

beach at the east and west ends of the island.

Presently three platforms can be seen from Sable Island.  The Thebaud platform (10 km SW of the island, in a water depth of 27 m) does preliminary processing of natural gas from the Thebaud wells and from the satellite platforms North Triumph (40 km S of the island, water depth 76 m) and Venture (5 km E of the island, water depth 22 m).  From Thebaud, the gas is sent to the mainland by pipeline.  All three platforms are operated by ExxonMobil.

Archive:  The Thebaud Flare  (September 2002)

In the sky southwest of Sable Island, a heavy black smudge has been visible, almost daily, since 1999 - it is a plume of exhaust from the flare stack on the Thebaud platform.

The flare stack on gas and oil platforms normally serves two functions:

• Safety.  If, in the event of an accident or leak, operators need to depressurize the facility, natural gas is sent into the flare stack and burned off.

• Environmental.  Under normal operating conditions, the flare serves to control and reduce emissions.   Numerous pressure relief valves on pressure vessels would occasionally vent natural gas, but instead of being released to the environment, vented material goes up the flare stack and is burned producing carbon dioxide.   Flares are typically 80-98% efficient at converting hydrocarbons to CO2.

Normally a small portion of gas is sent up to the flare head and burned to serve as a pilot light.  Should an incident occur, any increase in amount of natural gas shunted into the stack would be ignited immediately at the flare head.   In high winds it is sometimes necessary to increase the amount of pilot gas.  So, a continuous flame at the top of the flare stack is normal.

However, the large amount of black smoke produced by the Thebaud flare is not normal, and such emissions would usually be seen only in "upset conditions".   In this regard, Thebaud is not operating efficiently - a situation which has persisted for several years.

Depending on atmospheric conditions the pollutants billow up into the sky and hang like a storm cloud above Thebaud, or spread out in a long dark smear over the horizon.  

The Thebaud platform, as seen from Sable Island...

Click on thumbnails for more information

Archive:  The Thebaud Flare update  (October 2003)

Since autumn 2002, ExxonMobil engineers have been working to reduce or eliminate the smoke emitted from the flare stack at the Thebaud platform.  During much of summer 2003 low visibility in fog prevented observation of the platform from Sable Island. Later in the season, when Thebaud was more often visible, there were some days when the flare stack was producing a clean flame, however, on most days a plume - ranging from a moderate trail of smoke to a heavy black pall in the air above the platform - was present.  

At this time there are no regulations regarding atmospheric emissions by the offshore energy industry in this region. However, the Canada - Nova Scotia Offshore Petroleum Board (CNSOPB) is now developing air quality standards.  CNSOPB is responsible for environmental protection during all phases of offshore petroleum activities, from initial exploration to abandonment. CNSOPB is an independent joint agency of the Governments of Canada and Nova Scotia, and is empowered to act in all matters relating to the petroleum resources in Nova Scotia's offshore area.

The Board is comprised of five members who are appointed for fixed terms of office. The Government of Canada and the Government of Nova Scotia each appoint two members, and the chairman is jointly appointed by both governments.  The Chief Executive Officer reports to the Board and is responsible for the day to day operations of the Board and a staff of about twenty professional and support personnel. CNSOPB has five management groups: environment, resources and rights; administration and industrial benefits; health and safety; and legal.

CNSOPB's environmental assessment (EA) process begins at the Calls for Bids stage with a broad assessment which identifies ("red-flags") environmental concerns. These issues may be addressed by the Board deciding to not accept bids on a particular area, or, if bids are accepted, through subsequent project-specific EAs.  All projects, including seismic programs and exploratory wells, must undergo an EA prior to approval by CNSOPB.  The Board is assisted by its Fisheries and Environmental Advisory Committee (FEAC).  CNSOPB participates in initiatives led by the Department of Fisheries and Oceans (DFO) related to marine protected areas and management under the Oceans Act. The Board has signed memorandums of understanding with both DFO and Environment Canada, and annual work plan projects are developed with each department and implemented under these memorandums.  CNSOPB has the power to conduct a public review of any matter within its mandate where it is in the public interest to do so.

Regarding the Thebaud flare, on September 10, 2003, Andy Parker of CNSOPB provided the following update:

The Canada - Nova Scotia Offshore Petroleum Board (CNSOPB) continues to monitor and audit the flare operation at the Thebaud production platform. At the present time, there are no formal standards for air emissions related to offshore oil and gas developments in regulation and limited reference in the Offshore Waste Treatment Guidelines. The CNSOPB has, however, recognized the smoke from the Thebaud platform flare as an issue and has addressed the matter through the following:

• Late 2002/early 2003 - Review of the Development Plan Application and Environmental Impact Statement to confirm operator commitments related to the Thebaud flare. No commitments related to flare emissions that can be referred to as a condition of authorization;

• January 14, 2003 - CNSOPB letter to ExxonMobil requesting that assessments for pre and post modification scenarios be submitted, including fuel streams directed to the Thebaud flare, combustion efficiency of the flare, dispersion of flared gases, and acceptability of risk(s) posed to the environment;

• February 26, 2003 - CNSOPB and ExxonMobil staff met to discuss CNSOPB expectations related to the flaring modification scenarios;

• April 2003 - CNSOPB approved a yearly flaring rate for the offshore facilities (0.5% of raw gas produced);

• April 7, 2003 - ExxonMobil letter to the CNSOPB outlining their assessment plans for the Thebaud platform flare.  The CNSOPB expects to receive results of the assessment of the Thebaud platform flare in the fall of 2003. Additional action by the CNSOPB or ExxonMobil will be addressed after this assessment.

• In addition, an Environmental Studies Research Fund (ESRF) study examining air quality standards for oil and gas activities in other jurisdictions is currently underway. The results of the study are expected to be complete in 2003 and will be reviewed by the CNSOPB. It is expected that these will form the basis for inclusion of air emission standards in the Offshore Waste Treatment Guidelines.

Sable Island horses on the south beach in August 2003. 

The Thebaud platform - with no sign of smoky emissions - is in the distance.

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