Brent crude oil headed up towards 2015 highs above $68 a barrel on Thursday after official data showed the first drawdown in U.S. crude inventories since January, evidence the market there is balancing after months of heavy oversupply. U.S. crude stocks fell 3.9 million barrels last week, the first drop in four months, the Energy Information Administration said on Wednesday. Stronger-than-expected demand growth and a slowdown in U.S. crude supply has boosted oil prices by 50 percent from a six-year low hit in January, despite ample supply.