(6)	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 years ended December 31, 2015, 2014 and 2013 (in thousands, except for number of projects):

	2015		2014			2013
Balance at beginning of period	$	2,996	$	6,964		$	57,360
Additions to capitalized exploratory well costs pending the determination of proved reserves		1,165		18,747			39,832
Reclassifications to wells, facilities and equipment based on determination of proved reserves		¾		(15,735	)		(84,840	)
Capitalized exploratory well costs charged to expense		¾		(6,980	)		(5,388	)
Balance at end of period		4,161		2,996			6,964
Less exploratory well costs that have been capitalized for a period of one year or less		(1,165)		(2,996	)		¾
Capitalized exploratory well costs that have been capitalized for a period greater than one year	$	2,996	$	¾		$	6,964
Number of projects that have exploratory well costs that have been capitalized for a period greater than one year		1		¾			1

As of December 31, 2015, the $3.0 million of capitalized exploratory well costs that have been capitalized for more than one year is comprised of one well in our Marcellus Shale area which is currently in the completion phase. The following table provides an aging of capitalized exploratory well costs that have been suspended for more than one year as of December 31, 2015 (in thousands):

	Total			2015				2014
Capitalized exploratory well costs that have been suspended for more than one year	$	2,996		$	¾			$	2,996