Weakening economic outlook and US production surge, today, overshadowed expected supply cuts by OPEC in the international market. Brent crude futures were down by 0.4%, at $66.55 a barrel. US WTI crude futures lowered 0.2%, to $57.07 a barrel. US crude oil production has seen an almost 25% rise this year, with drillers pumping a record 11.7 million barrels per day.