Canada's oil and gas industry is committed to responsible water use and we have made significant progress in reducing our use of fresh water.
In situ, or underground, production technologies have been used in the oil sands for decades to extract bitumen that’s too deep to mine – a full 80 per cent of the resource in Northern Alberta lies deep below the surface.
Other in situ production processes, such as steam assisted gravity drainage (SAGD) use natural gas to heat water into steam which is pumped through a horizontal well underground to heat and loosen the bitumen. The bitumen drains into a second horizontal well and is pumped to the surface. While some water is lost in the process, most of it is recycled. The steam generation and water recycling facilities make up the majority of the capital equipment and operating costs of a SAGD project.
Petrobank Energy and Resources has spent the last three years field-testing a new process for in situ production that doesn’t require much water or natural gas. The company’s patented THAI™ technology (Toe to Heel Air Injection) is a unique in situ combustion process that has shown to produce more of the resource, while significantly limiting the environmental footprint. While it uses some water for the intitial steaming, that water and more is returned to the surface, treated and returned to the environment.
After being proven at Petrobank’s Whitesands pilot project south of Fort McMurray, the technology is poised for commercialization in other oil sands and heavy oil reserves in western Canada and around the world.
The THAI™ process combines controlled combustion with vertical and horizontal wells. The simple equation is: air in, upgraded heavy oil out.
To begin the process, bitumen around the “toe” of the horizontal well is heated with steam. Once this approximately three-month heating cycle in a bitumen reservoir is complete, the steam is shut off and air is injected into the vertical well to create a combustion reaction in the reservoir.
Through the controlled injection of air, an estimated two metre thick combustion front begins to move along the horizontal well at about 10 inches (25 centimetres) a day toward the “heel” of the horizontal well. As it heats up, the bitumen drains into the horizontal production well and brought to the surface through natural pressure.
Because the combustion front heats the bitumen to 400 degrees, the oil is also partially upgraded underground. The heat causes a portion of the asphaltine content of the oil to be left behind as coke that is the fuel for the continued combustion.
“It’s an ideal technical solution,” says Chris Bloomer Petrobank’s Chief Operating Officer for Heavy Oil. “Not only does THAI™ allow for a higher recovery of the resource – from 70 to 80 per cent – greenhouse gas emissions are cut by half and there is negligible fresh water use.” Another environmental benefit is a smaller surface footprint and easier reclamation.
THAI™ also reduces capital and operating costs because it requires only one horizontal well and does not need the large steam and water handling facilities associated with SAGD.