Now that multinational energy producers have sold their stakes in Canada’s oil sands, local companies are hatching plans to make some real changes.  Cenovus Energy Inc. and Canadian Natural Resources Ltd. are betting they can exploit new technologies and their deeper understanding of Canadian-specific issues, such as environmental rules and relations with native communities, to profit from one of the world’s biggest hydrocarbon reserves without their former partners.  “The oil sands require a focus on environmental issues like carbon pricing, indigenous issues, things like that, that are very specific kinds of skills that companies need to have for Alberta, for Canada,” said Harrie Vredenburg, a professor at the University of Calgary’s Haskayne School of Business. “Some of the multinationals are not necessarily particularly suited to that. In all those things, it does favor the Canadian firms.”