In the quest to produce as much of pushing it along the horizontal well. In
Alberta’s bitumen as efficiently as possible, order to get the process going, steam is
steam injection may not be the only road injected to preheat the reservoir and
to success. It has yet to be proven soften the bitumen.
commercial, but one company believes air
injection and the resulting in situ “We need to get some drainage before we
combustion could be the answer. initiate combustion,” Bloomer explains.
“Combustion reactions are like a Air is taken straight from the atmosphere
sledgehammer, much more aggressive and is compressed, then injected. Ignition
than steam,” says John Wright, president occurs and a combustion front develops,
and CEO of Petrobank Energy and intended to sweep across the reservoir
Resources. Petrobank subsidiary from the horizontal well’s toe to its heel at
Whitesands Insitu is piloting a new about 20 centimetres per day. The
combustion technique in Alberta’s oil company says in the THAI context, the term
sands, and Wright says it is a “step change” “combustion” refers to a high temperature
technology. “All the advances the oil and oxidization of the heavier part of the
gas industry has managed to achieve over bitumen, also known as coke, which is left
the last 80 years have been step changes. behind as the process proceeds.
They have been major changes to existing
techniques.” “This oxidation does not produce flames,
but rather is like charcoal burning in a
Patented in Canada, the United States and barbeque. With low air flux, the coals turn
Venezuela, the process is called toe-to-heel grey and burn slowly, whereas when one
air injection ( THAI). Whitesands president blows on the coals they burn more rapidly
and CEO Chris Bloomer says the and glow red.”
technology was “discovered” in 1993 by
University of Bath improved oil recovery
chair Dr. Malcolm Greaves and Petroleum
Recovery Institute (now Alberta Research
Bloomer explains that what is left behind is basically metals in sand, and that allows for “THAI is a huge leap
efficient production of the resource.
Council) researcher Dr. Alex Turta.
for the effectiveness
“You get a very permeable, porous
of combustion
“They were looking for new processes and reservoir left behind.”
technologies for heavy oil recovery and oil
recovery in general,” Bloomer says. After oil production stabilizes, constant air processes,”
“Combustion is the best way to get heat injection is maintained to ensure a
into the reservoir.” relatively constant flow through the
horizontal well. In lab testing using five
He uses the term discovered rather than litres of oil in sand within three-dimensional
invented to describe the evolution of THAI cells at the University of Bath, the THAI
because in situ combustion is not a new process typically recovered over 80 per
concept to the oil and gas industry around cent of the original oil in place, as well as
the world. increasing its API gravity by as much as
eight degrees. That means THAI-produced
“The combustion aspect is not the big oil would require much less upgrading
issue, it’s the effectiveness of it,” he says, than other in situ recovery processes in
adding that ultimately has to do with well order to become a more valuable and
configuration. “They discovered this coveted product.
particular well orientation was the most
effective way of using in situ combustion.” “We recovered a very high percentage of
the oil. When we took that and started the
Bloomer explains
The well configuration goes like this: numerical simulations in a field reservoir
similar to steam assisted gravity drainage, setting, we saw the same thing,” Bloomer
production comes from a pair of wells. says. “We had very effective heat
However, instead of employing two parallel generation and very effective sweep across
horizontal wells, a THAI pair is a set of one the reservoir. It reinforced what we saw in
vertical well and one horizontal well. The the lab.”
horizontal well, placed near the base of the
reservoir serves as the production path, The project proponents say in situ
while the vertical well, placed high in the combustion for oil and gas production
reservoir is used to inject air. Like a human could be said to date as far back as 1888,
foot, the horizontal well has a toe and a when it was suggested the in situ
heel—where it bends is its heel and where conversion of coal into combustible gases
it ends is its toe. The idea is to effectively might be possible. In the 1920s and 1930s,
melt the bitumen through combustion, it is said there were a number of field tests
