Black gold prices are proving a very slippery slope. The cost of oil dropped below $50 a barrel today to $48.68 — a new six-year low. OPEC could’ve eased up on production to stabilize prices, but members decided in November to continue pumping 30 million barrels a day. Now the world is facing a possible surplus, just as Europe and Asia face economic woes that hurt demand. Analysts are beginning to think the slide will continue throughout much of 2015. Will we see $40 barrels this year?