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ASSET RETIREMENT OBLIGATIONS (Details)
$ in Thousands
6 Months Ended
Jun. 30, 2018
USD ($)
Activity related to ARO liability  
Liability for asset retirement obligations at the beginning of the period $ 4,368
Liabilities settled and divested (110)
Additions 544
Acquisitions 2,333
Accretion expense 131
Revisions in estimated cash flows (720)
Liability for asset retirement obligations at the end of the period $ 6,546