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Oil and natural gas properties (Tables)
 12 Months Ended
Dec. 31, 2016
Extractive Industries [Abstract]  
Schedule of oil and natural gas properties
Oil and natural gas properties are comprised of the following:
 
 
 December 31,
 
2016
 
2015
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
)
Oil and natural gas properties, net
$
621,343

 
$
759,091