Antero Resources (NYSE: AR) has announced that proved reserves at December 31, 2014 were 12.7 Tcfe, a 66% increase compared to proved reserves at December 31, 2013, in each case assuming ethane rejection. Proved, probable and possible (3P) reserves at year-end 2014 totaled 40.7 Tcfe, which represents a 16% increase compared to the previous year, also assuming ethane rejection. Antero's December 31, 2014 proved and 3P reserves exclude 615 and 1,535 million barrels of ethane, respectively, due to the relationship between ethane and natural gas futures pricing which indicates that ethane will be rejected. Additionally, the company's reserves exclude any reserves attributable to Antero's Utica dry gas resource in West Virginia and Pennsylvania.

The Marcellus Shale accounted for 94% of proved reserves and the Utica Shale accounted for the remaining 6%. Excluding 2014 production, 5.0 Tcfe of the 5.4 Tcfe of proved reserves added during 2014 were attributed to the Marcellus Shale. Total proved NGLs and oil reserves increased by 193 million barrels and 18 million barrels, respectively. Positive performance revisions of 361 Bcfe were primarily due to improved Marcellus well performance from shorter stage length (SSL) completions. Negative revisions of 1.4 Tcfe were due to the reclassification of 191 dry gas locations to the probable category in order to comply with the SEC five-year development rule.

Proved developed reserves increased by 88% from year-end 2013 to over 3.8 Tcfe at December 31, 2014. The company added 135 Marcellus and 45 Utica wells to proved developed reserves in 2014. The percentage of proved reserves classified as proved developed increased to 30% at December 31, 2014 as compared to 27% at year-end 2013. Proved undeveloped reserves increased by 58% as a result of the successful execution of Antero's Marcellus and Utica shale development drilling plans resulting in the addition of 182 gross proved undeveloped drilling locations.

Antero's estimate of drilling and development costs incurred during 2014, including drilling and completion of $2.5 billion and leasehold costs of $840 million, is approximately $3.3 billion.

Antero is based in Denver.