A sour gas leak that resulted in the evacuation of 600 people from their homes will be thoroughly investigated to prevent any risk of a similar occurrence in the future, says the Alberta Energy and Utilities Board (EUB).
But some critics say all oil and gas operations near populated areas need a safety review.
"We'll take it from step one and look at the story of the well and all aspects that could have led to this situation," said EUB spokesman Darin Barter.
Acclaim Energy Trust's Acheson well west of Edmonton was undergoing a routine workover last week when an uncontrolled release of sour gas, containing poisonous hydrogen sulphide (H2S), occurred.
"It was a suspended (dormant) well," said Acclaim spokesman Kerk Hilton.
"We were trying to understand why and figure out its future performance."
Calgary-based Acclaim purchased the former Chevron Canada Resources property as part of a larger $1.089-billion deal that saw Chevron exit Western Canada's conventional oil and gas business in June 2004.
The H2S level in the well at the time of release was 0.037 per cent or 370 parts per million (PPM), classified by the Alberta Energy and Utilities Board as low sour content.
But even at 100 PPM, H2S exposure can result in the loss of sense of smell in two to 15 minutes and may burn the throat or cause headaches. At 700 PPM there is immediate unconsciousness, say Alberta workplace health and safety regulations.
Following the release of gas at 8 a.m. on Dec. 12, Acclaim Energy Inc., the operating subsidiary of Acclaim Energy Trust, activated its emergency response plan.
Area residents, including members of the nearby Enoch reserve, were relocated to hotels at Acclaim's expense.
By mid-week, the afflicted area had shrunk to a one-kilometre radius of the well, and many - but not all - families were being allowed back into their homes.
"Our first priority remains the safety and comfort of the public, our employees and contractors. We are working with well service and control specialist Safety Boss to stop the uncontrolled flow of gas," Paul Charron, president and CEO of Acclaim Energy Trust, said in a statement.
Five air-monitoring stations were set up, but Acclaim subsequently increased the number of air monitors within a one-kilometre radius of the wellhead to 14. By mid-week, levels of H2S within the zone ranged from zero to 23 PPM.
While workers struggled to cap the well, hindered by water coming up and surrounding the casing, an unexpected ignition took place Monday evening, sending flames into the sky. Two workers near the well at the time were treated for minor injuries.
Safety Boss, the Red Deer-based company with international firefighting expertise, extinguished the blaze with a dry chemical agent after first using water to cool the fire.
However, the company later decided to deliberately re-ignite the fire to eliminate odours and further H2S emissions.
"A controlled fire will burn off the H2S, rather than have it accumulating in low-lying areas at the wellsite where it has the potential to spark and reignite unexpectedly," said Acclaim Energy Trust's chief operating officer Brent DeFosse.
The company said the decision to re-ignite the well was made after consultation with Alberta Environment, Capital Health, the City of Edmonton and the EUB. The process may take as long as two weeks to bring the well fully under control, the company said, and will include drilling relief wells to reduce the pressure of the original well.
The Acheson incident, however, has raised the profile of well safety issues. Provincial NDP energy critic David Eggen called for a thorough public review of oil and gas well safety near populated areas.
Eggen said there are at least 113,000 dormant gas wells in Alberta - and that people and sour gas don't mix.
"My understanding is that there are more than 300 sour gas wells in the Greater Capital Region. This is going to be an emerging issue for years to come," said Eggen.
"Increasingly, as the population of Alberta increases, there's less and less areas to drill in that aren't in close proximity to populated areas. Of course, oil and gas are the foundation of our economy and we want to encourage it. Let's just make it a tenable situation so that there are controls in place that we can be proud of and rely on."
The chief of the Enoch First Nation is also calling for the 52-year-old well to be permanently abandoned once it is under control.
"I definitely think it should be closed. It is an old well," said Chief Ron Morin.
"I'm hoping the province will have some kind of review or discussion for some of these old wells, especially when you are close to major urban centres."
Meanwhile, previously-announced changes related to dealing with sour gas are already being put in place, said Greg Gilbertson, senior advisor to the EUB's public safety and sour gas initiative.
Eighty-seven recommendations are in the process of being implemented, all of which arose out of an EUB report from an advisory committee that travelled across Alberta during the year 2000.
To date, 50 recommendations have now been enacted and Gilbertson expects the remaining 37 to be adopted over the next year or two.
"Those 87 recommendations encompassed widely divergent topics such as planning, health effects, information, technical requirements, emergency response and ways to improve communications with the public and First Nations," said Gilbertson.
The EUB has worked closely with Alberta Health and Wellness, said Gilbertson.
"One of the things they did was to put together a technical review regarding the health effects associated with short-term exposure to low levels of hydrogen sulphide.
"We had also found, in speaking with people around the province, including a lot of medical professionals, that there didn't seem to be a common treatment criteria. Alberta Health and Wellness, in conjunction with the Alberta Medical Association (AMA), contracted a physician who has put together a set of clinical practice guidelines."
The guidelines are now being reviewed by the AMA and Health and Wellness, and are expected to be made available in the near future to all the regional health authorities, he added.
Gilbertson said the EUB is also keeping an eye on ongoing medical research into the effects of sour gas and is looking forward to the information that will eventually emerge out of a human exposure study now under way at Rutgers University in the U.S.
Recent figures show that about one-third of all the gas produced in Alberta comes from sour gas wells. In 2002, Alberta produced 136 billion cubic metres of gas. Of that, 42 billion cubic metres were originally from sour gas fields - enough gas to heat 7.5 million houses for one year.
- With files from CP (Laura Severs can be reached at laura@businessedge.ca)
