Oil-sands companies are poised to crank up billions' worth of new production just when the market doesn't need it, deepening a supply glut even as profit margins in the high-cost sector shrivel. Major producers, such as Suncor Energy Inc., ConocoPhillips Co., Husky Energy Inc. and others, are pressing ahead with expansions that could add roughly 800,000 barrels per day of fresh capacity in northern Alberta by 2018, according to new data compiled by ARC Financial Corp. Oil prices fell to near four-month lows on Monday after a steep drop in Chinese stock markets and on more evidence of a global oil supply glut that has halved prices over the past year.