Royal Dutch Shell has agreed to sell most of its Canadian oil sands assets for $7.25 billion to Canadian Natural, the company said on Thursday. The deal also includes a joint acquisition by Shell and Canadian Natural of Marathon Oil Canada Corporation, a subsidiary of Marathon Oil, for $1.25 billion each to be paid in cash, Shell said. Shell will sell its existing and undeveloped Canadian oil sands interests and reduce its share in the Athabasca Oil Sands Project (AOSP) to 10 percent, but it will remain as operator of the AOSP Scotford upgrader and the Quest carbon capture and storage project. (Reporting by Karolin Schaps; editing by Jason Neely)