(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 year ended December 31, 2012, 2011 and 2010 (in thousands except for number of projects):


	2012			2011			2010
Balance at beginning of period	$	93,388		$	23,908		$	19,052
Additions to capitalized exploratory well costs pending the determination of proved reserves		153,250			86,996			28,897
Reclassifications to wells, facilities and equipment based on determination of proved reserves		(184,298	)		(17,516	)		(24,041	)
Divested wells		(4,980	)		—			—
Capitalized exploratory well costs charged to expense		—			—			—

Balance at end of period		57,360			93,388			23,908
Less exploratory well costs that have been capitalized for a period of one year or less		(45,965	)		(83,860	)		(13,181	)

Capitalized exploratory well costs that have been capitalized for a period greater than one year	$	11,395		$	9,528		$	10,727

Number of projects that have exploratory well costs that have been capitalized for a period greater than one year		5			3			4

As of December 31, 2012, the $11.4 million of capitalized exploratory well costs that have been capitalized for more than one year is comprised of two wells waiting on pipelines and three wells not operated by us. Four of the five wells are in our Marcellus Shale area. The following table provides an aging of capitalized exploratory well costs that have been suspended for more than one year as of December 31, 2012 (in thousands):


	Total		2012		2011		2010		2009		2008
Capitalized exploratory well costs that have been capitalized for more than one year	$	11,395	$	970	$	5,946	$	72	$	2,884	$	1,523