(7) SUSPENDED EXPLORATORY WELL COSTS

We capitalize exploratory well costs until a determination is made that the well has either found proved reserves or that it is impaired. Capitalized exploratory well costs are presented in natural gas and oil properties in the accompanying consolidated balance sheets. If an exploratory well is determined to be impaired, the well costs are charged to exploration expense in the accompanying consolidated statements of operations. The following table reflects the changes in capitalized exploratory well costs for the six months ended June 30, 2013 and the year ended December 31, 2012 (in thousands except for number of projects):

	June 30, 2013			December 31, 2012
Balance at beginning of period	$	57,360		$	93,388
Additions to capitalized exploratory well costs pending the determination of proved reserves		41,405			153,250
Reclassifications to wells, facilities and equipment based on determination of proved reserves		(66,221	)		(184,298	)
Divested wells		—			(4,980	)
Balance at end of period		32,544			57,360
Less exploratory well costs that have been capitalized for a period of one year or less		(12,025	)		(45,965	)
Capitalized exploratory well costs that have been capitalized for a period greater than one year	$	20,519		$	11,395
Number of projects that have exploratory well costs that have been capitalized for a period greater than one year		8			5

As of June 30, 2013, $20.5 million of capitalized exploratory well costs have been capitalized for more than one year with five of the wells waiting on pipelines and three of the wells currently in the completion stage. Four of the wells are not operated by us and seven of the wells are in Pennsylvania. In first six months 2012, we sold a seventy-five percent interest in an East Texas exploratory well. Refer to Note 4 for additional information. The following table provides an aging of capitalized exploratory well costs that have been suspended for more than one year as of June 30, 2013 (in thousands):

	Total					2013									2012									2011									2010									2009									2008
Capitalized exploratory well costs that have been capitalized for more than one year	$		20,519			$		3,828					$				6,965					$				5,247					$				72					$				2,884					$				1,523