Carbon dioxide that is being injected into a rock reservoir for storage as part of a Saskatchewan oil field operation is being held safely deep underground and is not leaking to the surface, according to a study.
The report, commissioned by Calgary-based Cenovus Energy Inc. after concerns were raised that its carbon-sequestration initiative in Weyburn, Sask., where greenhouse gases are buried instead of being sent into the atmosphere, was responsible for a series of unusual environmental events on a nearby property.
"The results, which have been peer-reviewed, should provide complete assurance to landowners and the public, that the carbon dioxide that we are injecting is staying put and that our Weyburn operation is safe," Cenovus vice-president Brad Small told reporters on Tuesday.
Carbon capture and storage has been touted as a solution for the coal-fired power sector as well as the oil sands. But there are questions about safety, and complaints about possible problems at Weyburn, a 215-square kilometre oil field in southeastern Saskatchewan, fuelled fears.
Since 2004, nearby landowners, Jane and Cameron Kerr, had reported odd algae blooms, fizzy water and dead animals, which prompted them to suspect that CO2 was bubbling up. The couple hired Petro-Find Geochem Ltd. to conduct a soil analysis, which reported high levels of carbon dioxide in soil gas, and blamed activities at the Weyburn storage operation.
However, scientists with the Regina-based Petroleum Technology Research Centre, which has been conducting a long-term study of the Weyburn project for the International Energy Agency, disputed those findings.
Cenovus told the Saskatchewan government last February it would hire an independent company to test the soil, as well as ground and surface water, and check the integrity of its infrastructure. The petroleum research centre found the Cenovus study to be scientifically "appropriate and robust" and agreed with its conclusion.
Court Sandau, the lead scientist behind the Cenovus assessment, said carbon fingerprinting determined that gas didn't come from the company's Weyburn project. Although one sample location did show abnormally elevated levels of gas – up to 90 times greater than other sites – the CO2 presence was natural in origin and posed "no risk," he added.
Paul Lafleur, who conducted the original study that pointed the finger at Cenovus, said he hasn't looked at the latest report and referred questions to Ecojustice, an environmental group that has worked with the Kerrs.
Ecojustice lawyer Barry Robinson is still reviewing the Cenovus report, but said the high levels of CO2 detected near the Kerr property is disconcerting. The Kerrs have since moved because of their environmental concerns, but still want to get to the bottom of the strange occurrences.
Another independent body, the University of Regina's International Performance Assessment Centre for Geologic Storage of CO2, has also been examining the Weyburn operation; its findings are to be released Dec. 12.