Asset Retirement Obligations

12 Months Ended

Dec. 31, 2016

Asset Retirement Obligations

Asset Retirement Obligations

(8) Asset Retirement Obligations

The following is a reconciliation of the Company’s asset retirement obligations for the years ended December 31, 2015 and 2016 (in thousands).

	2015		2016
Asset retirement obligations—beginning of year	$	16,614		30,612
Obligations incurred for wells drilled and producing properties acquired		9,213		4,487
Revisions to prior estimates		3,130		(4,836)
Accretion expense		1,655		2,473
Asset retirement obligations—end of year	$	30,612		32,736

Revisions to prior estimates in 2016 are primarily due to a decrease in the estimated costs to plug and abandon the Company’s horizontal wells.  Revisions to prior estimates in 2015 are primarily due to a decrease in the estimated economic lives of the Company’s wells as a result of the decrease in commodity prices during 2015.  Asset retirement obligations are included in other liabilities on the consolidated balance sheets.