Interesting story from the Globe and Mail about new techniques being used to exploit Alberta’s oil sands which offer a “potential sea change in how Canadian companies wring energy from the ground.”
Most companies have traditionally pumped steam into their reservoirs to move the putty-like oil deposits, a process called steam-assisted gravity drainage, but this consumes a lot of costly natural gas.
Calgary-based Petrobank has taken a different route at Whitesands, injecting hot air into the ground to force the bitumen – the heavy crude produced from the oil sands – to the wells. “This is what all our work is for,” says Dave Reddecliff, operations manager at the plant. “It might look simple, but it’s also really exciting. To me, this is the answer for the oil sands.”
The method, Toe-to-Heel Air Injection or THAI, is based on techniques that have been around since the 1920s. It is used in countries such as India, Kazakhstan and Romania. Hot air is injected down one vertical well, creating a combustion front that forces the crude toward a second vertical well, where it is extracted.
The process has historically been inefficient, as the air has a tendency to break into the second well, ending production. To overcome those problems, Petrobank has added a twist to the system. THAI uses a horizontal extraction well, employing gravity to increase the proportion of crude recovered.
However, the company believes the combustion process could increase recovery rates in heavy crude oil reservoirs to between 70 per cent and 80 per cent, a step up from the 40 per cent typically seen using the alternative method.
Chris Bloomer, Petrobank’s vice-president of heavy oil argues “This is a game-changing project; we proved it in the laboratory, but we needed to prove it in the field. We’ve done that; now we just have to optimize and enhance it.”