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ASSET RETIREMENT OBLIGATIONS
3 Months Ended
Mar. 31, 2013
ASSET RETIREMENT OBLIGATIONS  
ASSET RETIREMENT OBLIGATIONS
7.           ASSET RETIREMENT OBLIGATIONS

We estimate the fair values of AROs based on historical experience of plug and abandonment costs by field and, assumptions and judgments regarding such factors as the existence of a legal obligation for an ARO; estimated probabilities, amounts and timing of settlements; the credit-adjusted risk-free rate to be used and inflation rates.  The following table sets forth the composition of asset retirement obligations rollforward:

Beginning January 1, 2013 liability
  $ 11,029,206  
Accretion expense
    122,638  
Liabilities incurred
    2,667  
Liabilities settled
    (179,601 )
Revisions
     
Ending March 31, 2013 liability
  $ 10,974,910