Encana Oil & Gas (USA) Inc., a subsidiary of Encana Corp., Calgary, (Toronto: ECA; NYSE: ECA) has completed a benchmark upstream joint-venture development agreement with Northwest Natural Gas Co. (NYSE: NWN), a Portland, Oregon-based natural gas distributor. The Public Utility Commission of Oregon recently approved the agreement that will see Northwest Natural invest about US$250 million during the next five years to earn a working interest in certain sections of Encana's Jonah field in Wyoming. The arrangement provides NW Natural with secure, reliable and economic supplies of natural gas for ...