4. Property, Plant and Equipment

Property, plant and equipment at December 31 were as follows:

	2016		2015
	(In millions)
Exploration and Production
Unproved properties	$	710	$	958
Proved properties		4,258		4,202
Wells, equipment and related facilities		38,821		38,738
		43,789		43,898
Bakken Midstream		3,018		2,757
Corporate and Other		100		171
Total — at cost		46,907		46,826
Less: Reserves for depreciation, depletion, amortization and lease impairment		23,312		20,474
Property, Plant and Equipment — Net	$	23,595	$	26,352

Capitalized Exploratory Well Costs: The following table discloses the amount of capitalized exploratory well costs pending determination of proved reserves at December 31, and the changes therein during the respective years:

	2016			2015			2014
	(In millions)
Balance at January 1	$	1,415		$	1,416		$	2,045
Additions to capitalized exploratory well costs pending the determination of proved reserves		79			424			292
Reclassifications to wells, facilities and equipment based on the determination of proved reserves		—			(72	)		(629	)
Capitalized exploratory well costs charged to expense		(897	)		(356	)		(235	)
Dispositions and other		—			3			(57	)
Balance at December 31	$	597		$	1,415		$	1,416
Number of Wells at December 31		17			35			37

Additions to capitalized exploratory well costs primarily related to drilling activity at the Stabroek license offshore Guyana and in the Gulf of Mexico in 2016 and 2015. In 2014, additions related to the Deepwater Tano/Cape Three Points license offshore Ghana and in Kurdistan. Reclassifications to wells, facilities and equipment based on the determination of proved reserves primarily related to Equatorial Guinea in 2015, and the Stampede development project in the Gulf of Mexico in 2014.

Capitalized exploratory well costs charged to expense include the following:

2016: At the Hess-operated Equus natural gas project, offshore the North West Shelf of Australia in the fourth quarter of 2016, we terminated a joint front-end engineering study with a third party natural gas liquefaction joint venture and notified the Australian government of our intent to defer the project. As a result, we expensed all well costs associated with the project, including an exploration well completed in the second quarter of 2016, totaling $830 million. In the second quarter, we expensed costs associated with two exploration wells at the non-operated Sicily project in the Gulf of Mexico where hydrocarbons were encountered but we decided not to pursue the project due to the current price environment and the limited time remaining on the leases. We also expensed the cost of an unsuccessful exploration well at the non-operated Melmar project in the Gulf of Mexico, where noncommercial quantities of hydrocarbons were encountered.

2015: At the Dinarta Block in the Kurdistan Region of Iraq, we expensed an exploration well resulting from our and our partners’ decision to cease further drilling and relinquish the block. At the Deepwater/Tano Cape Three Points block, offshore Ghana, we expensed well costs primarily related to natural gas discoveries where we were unable to sufficiently progress appraisal negotiations with the regulator, and we expensed three wells with discovered resources offshore Australia that we determined would not be included in the development concept for the Equus project.

2014: At Green Canyon Block 469 in the Gulf of Mexico, we expensed a previously capitalized exploration well where it was determined no further development activities were planned.

The preceding table excludes exploratory dry hole costs of $167 million (2015: $54 million; 2014: $66 million), which were incurred and subsequently expensed in the same year.

Exploratory well costs capitalized for greater than one year following completion of drilling were $511 million at December 31, 2016, separated by year of completion as follows (in millions):

2015	$	238
2014		80
2013		48
2012		145
	$	511

Ghana: Approximately 55% of the capitalized well costs in excess of one year relates to our Deepwater Tano/Cape Three Points license (Hess 50% license interest), offshore Ghana. In 2014 we drilled three successful appraisal wells. Well results continue to be evaluated and development planning is progressing. The government of Côte d’Ivoire has challenged the maritime border between it and the country of Ghana, which includes a portion of our Deepwater Tano/Cape Three Points license. We are unable to proceed with development of this license until there is a resolution of this matter, which may also impact our ability to develop the license. The International Tribunal for Law of the Sea is expected to render a final ruling on the maritime border dispute in 2017. Under terms of our license and subject to resolution of the border dispute, we declared commerciality for four discoveries, including the Pecan Field which would be the primary development hub for the block in March 2016. We are continuing to work with the government on how best to progress work on the block given the maritime border dispute.

Guyana: Approximately 20% of the capitalized well costs in excess of one year relates to the Stabroek Block, offshore Guyana (Hess 30% participating interest), where the operator, Esso Exploration and Production Guyana Limited, announced a significant oil discovery at the Liza-1 well in the second quarter of 2015. During 2016, the operator completed a 17,000 square kilometer 3D seismic acquisition on the Stabroek Block and drilled the Liza-2 and Liza-3 wells, both of which encountered hydrocarbons. Pre-development planning is underway and we expect to be in a position to sanction the first phase of the Liza development in 2017.

Gulf of Mexico: Approximately 20% of the capitalized well costs in excess of one year relates to an appraisal well in the northern portion of the Shenzi Field (Hess 28% participating interest) in the Gulf of Mexico, where hydrocarbons were encountered in the fourth quarter of 2015. The operator is evaluating plans for developing this area of the field.

JDA: Approximately 5% of the capitalized well costs in excess of one year relates to the JDA in the Gulf of Thailand where hydrocarbons were encountered in three successful exploration wells drilled in the western part of Block A-18. The operator is currently evaluating well results and formulating future drilling plans in the area.