Exploratory Costs (Tables)

6 Months Ended

Jun. 30, 2018

Schedule of Capitalized Exploratory Wells

The following table sets forth capitalized exploratory well costs and includes additions pending determination of proved reserves, reclassifications to proved reserves and costs charged to expense:



	Three months ended June 30,						Six months ended June 30,
(in thousands)	2018			2017			2018			2017
Capitalized exploratory well costs at beginning of period	$	142,007		$	168,265		$	132,200		$	164,996
Additions pending determination of proved reserves	207,288			170,737			376,041			335,703
Reclassifications due to determination of proved reserves	(221,061		)	(197,601		)	(380,007		)	(359,298		)
Capitalized exploratory well costs at end of period	$	128,234		$	141,401		$	128,234		$	141,401

The following table sets forth capitalized exploratory well costs:



(in thousands)	June 30, 2018		December 31, 2017
Exploratory wells in progress (drilling rig not released)	$	31,743	$	10,879
Capitalized exploratory well costs capitalized for a period of one year or less	96,491		121,321
Total capitalized exploratory well costs	$	128,234	$	132,200