Asset Retirement Obligations

12 Months Ended

Dec. 31, 2018

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, 2017 and 2018 (in thousands):

	2017		2018
Asset retirement obligations—beginning of year	$	32,736		34,610
Obligations settled		(22)		—
Obligations incurred		4,044		9,981
Revisions to prior estimates		(4,758)		11,569
Accretion expense		2,610		2,819
Asset retirement obligations—end of year	$	34,610		58,979

Revisions to prior estimates in 2018 are primarily due to an increase in estimated abandonment costs for vertical wells. Revisions to prior estimates in 2017 are primarily due to an increase in the estimated economic lives of our wells as a result of increases in commodity prices in 2017 and improved well performance.  Asset retirement obligations are included in other liabilities on the Company’s consolidated balance sheets.