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Oil and natural gas properties - Schedule of Oil and Natural Gas Properties (Details) - USD ($)
Dec. 31, 2016
Dec. 31, 2015
Extractive Industries [Abstract]    
Proved property $ 9,695,367 $ 9,940,660
Unproved property 1,375,940 1,375,940
Total oil and natural gas properties, at cost 11,071,307 11,316,600
Less: accumulated impairment (8,283,321) (8,283,321)
Oil and natural gas properties, net of impairment 2,787,986 3,033,279
Less: accumulated depletion (2,166,643) (2,274,188)
Total oil and gas properties, net $ 621,343 $ 759,091