Oil prices decreased on Wednesday after OPEC's output rose to 31.6 million barrels a day and Greece defaulted on its 1.54 billion euros' payment to the IMF. New York-traded crude oil declined 1.3% to $58.74 a barrel, while the UK-traded Brent crude oil traded 0.8% lower to $63.64 a barrel by 10:00 AM GMT. In addition, last week US crude oil inventories soared by 1.9 million barrels.