Oil prices fell on Friday and ended the week 3 percent lower on lingering doubts over the extent of OPEC cuts, with sentiment worsened by concerns over the economic health of the world’s second-largest oil consumer, China, after it reported the steepest falls in overall exports since 2009. Record Chinese crude imports of 8.6 million barrels per day in December helped to buoy prices somewhat, traders said, but they could not hide underlying fears over the overall health of the world’s second-biggest economy.