2 minute read Birds fly over storage tanks on a Continental Resources oil production site near Williston, North Dakota January 23, 2015. REUTERS/Andrew Cullen Shale oil producer Continental Resources (CLR.N) on Thursday said it will ramp up activity in North Dakota's Bakken shale field this year as it shifts more of its production operations to crude oil from natural gas. The company said roughly 70% of its well completions in the second half of the year will be focused on the Bakken versus about 50% of completions at the start of the year. The shift comes as the company is re-orienting its production portfolio to focus more heavily on oil, Chief Executive Officer Bill Berry told investors during an earnings call.