Like other oil sands producers, Cenovus Energy Inc. uses water to create steam for in situ (in place) operations to soften thick underground bitumen for recovery. Getting more out of every barrel of water to minimize environmental impact is constantly top of mind.
So, when a number of years ago the company looked for new ways to substantially ramp up its water recycling rate, they challenged conventional thinking. The vast majority of the water Cenovus uses to make steam is unfit for human consumption or agriculture and is recycled over and over again.
In the past, it’s been the norm for companies to expect steam boilers to convert about 80 per cent of the water they use into steam. The remaining 20 per cent (called blowdown water) has usually been disposed of or treated with chemicals because it contains salts and other impurities. Cenovus decided to rethink this approach and came up with an idea to use blowdown water directly without treatment.
“Our engineers challenged the belief that lower quality water could not be used without treatment to generate steam safely and economically,” says Susan Sun, a water treatment engineer at Cenovus. At the time, it was believed that impurities in the water could hurt efficiency or even cause boiler damage.
After some investigation of their own, Cenovus’ technical team proposed developing a new process to run blowdown water through a second boiler. This innovative approach would re-boil leftover water from the first boiler without treating it. The second boiler (the blowdown boiler) would then convert most of this water into steam. The result, they predicted, would improve water use efficiency with less leftover water and minimal environmental impact.
To prove this idea, the team carried out a small field pilot in 2007. From this trial, they gained valuable learnings that helped refine the boiler design. In late 2010, they installed a commercial-sized blowdown boiler at the company’s Foster Creek operation. In early 2011, the boiler was examined. The blowdown equipment showed no sign of significant scaling, despite handling large volumes of untreated water. The demonstration was a success!
Since 2015, Cenovus has expanded the technology to four units at Foster Creek and two at its Christina Lake oil sands facility. Thanks to this technology, the company has the ability to convert more than 90 per cent of every barrel of water to steam, a big step change. It can recycle more water, cutting water disposal by half, and using fewer chemicals to treat the water that remains. In addition, by decreasing the need to treat water for steam production, operating costs can also be reduced.
Sun says the technology is now part of the company’s commercial operations has been shared widely with other COSIA members. Today, this success is inspiring the company to explore new technologies that improve environmental performance elsewhere.
“The learnings have been huge. It’s triggered lots of ideas, encouraging us to go even further in other areas of operations,” says Sun.
Interested in other stories on water treatment? Check out these COSIA blogs.
• Sunlight drives novel process to clean up water
• Changing our world: clean steam
• World Water Day is on March 22
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Innovators, can you help us with our current water challenge? COSIA is looking for new research or potential technologies to passively treat dissolved organic compounds present in Oil Sands Process Water (OSPW). You can help make a difference to environmental performance in the mineable oil sands industry.
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