Oil prices rose for a second session today, moving further away from 12-year lows seen earlier this week. This comes on account of cold U.S. and European weather lifting demand for heating oil, as well as the bouncing back of many financial markets. International benchmark Brent is up at 29.50 dollar per barrel, off a 12-year low of 27.10 dollar.But the analysts caution the price rally is unsustainable given the soaring inventories amid persistent overproduction. Further, the meteorological data shows that the current cold snaps is likely to be short-lived. Thus the weaker demand for oil may again follow soon.