Oil collapsed by almost 40 percent this year to strike 11-year lows on chronic oversupply, demand fears and China’s slowdown, in a global commodities rout that sent metals tumbling.Europe’s benchmark oil contract, Brent North Sea crude, nosedived on December 22 to just $35.98 per barrel- the lowest level since early July 2004.And US benchmark West Texas Intermediate (WTI) oil tanked on December 21 to $33.98 a barrel- which was a point last seen in mid-February 2009.OPEC has continued to pursue its strategy to maintain its collective oil output despite abundant supplies of crude that have ravaged revenues.Crude futures have dived from more than $100 a barrel in July 2014 on the strong dollar and the stubborn worldwide oil supply glut.However, in both June and December, the Organization of the Petroleum Exporting Countries- which pumps 40 percent of the world`s oil- refused to slash output.The Saudi-backed policy is aimed at pushing oil prices lower in order to squeeze less-competitive players, including US shale producers, out of the market.The cartel- whose biggest player is Saudi Arabia- is currently producing an estimated 32 million barrels per day, above the group`s 30-million-barrel target.Added to the picture, the United States- the world`s biggest consumer of crude- revealed Wednesday that oil inventories swelled by 2.6 million barrels to 487.4 million barrels last week.That confounded expectations for a 2.5-million-barrel drop, and came alongside news of rising US production.Traders also weighed Saudi Arabia`s 2016 austerity budget, which suggested that the key crude exporter was planning for oil prices to stay low for the foreseeable future.The market is also fearful of surging oil supplies from Iran next year, once sanctions are lifted."With US production growing for the last few weeks and global inventories being near storage limits this is yet another reminder that the supply glut could take a long time to clear which may mean even lower oil prices in the near term," warned Gain Capital analyst Fawad Razaqzada."In fact, Saudi Arabia is already planning for lower oil prices next year. To make matters worse, Iran is ready to pump at least 500 million barrels per day more as soon as Western sanctions on its oil are lifted, possibly in early 2016."