BP has agreed to invest $2.5bn in the Sunrise oil sands project in Alberta, Canada, its first major investment since the Gulf of Mexico spillage.The UK firm, which owns 50% of the project in northern Alberta, said it was "a significant milestone" for the company and represented a "40-year secure and stable source of production for North America".BP's partner in the project, Husky Energy, predicts that Sunrise will produce 60,000 barrels of oil per day from 2014.Sunrise will use thermal technology to release the oil. Steam will pumped into the ground to liquefy bitumen trapped in sand to bring it to the surface to be treated.Environmental groups are vehemently opposed to the project, describing it as one of the most inefficent and damaging ways of producing oil.BP estimates Sunrise has over 3bn barrels of reserves, with the potential to produce more than 200,000 barrels a day.