6. Property, Plant and Equipment

Assets Held For Sale: At June 30, 2018, assets classified as “held for sale”, which comprised primarily of net property, plant and equipment, totaled $421 million and related to our joint venture interests in the Utica shale play in eastern Ohio ($365 million) and non-core acreage in North Dakota ($56 million). In addition, liabilities associated with the Utica shale play, which amounted to $2 million, were reported in Accrued liabilities in the Consolidated Balance Sheet.

Capitalized Exploratory Well Costs: The following table discloses the net changes in capitalized exploratory well costs pending determination of proved reserves during the six months ended June 30, 2018 (in millions):

Balance at January 1, 2018	$	304
Additions to capitalized exploratory well costs pending the determination of proved reserves		127
Balance at June 30, 2018	$	431

We expensed $13 million of exploratory wells costs incurred during 2018 that are not reflected in the table above. These costs relate to the Sorubim-1 well on the Stabroek Block, offshore Guyana and the Bunga Teruntum-1 well in the North Malay Basin, where commercial quantities of hydrocarbons were not encountered. Capitalized exploratory well costs capitalized for greater than one year following completion of drilling were $239 million at June 30, 2018 and primarily related to:

Gulf of Mexico: Approximately 50% of the capitalized well costs in excess of one year relates to the appraisal of 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 conducting appraisal activities on adjacent acreage and is evaluating plans for development of the northern portion of the Shenzi Field.

Guyana: Approximately 30% of the capitalized well costs in excess of one year primarily relates to the Liza-4 and Payara-1 wells on the Stabroek Block, offshore Guyana (Hess 30% participating interest), where hydrocarbons were encountered. The operator plans to integrate the Liza-4 discovery into the second phase of development, which is expected to be sanctioned in 2018. The operator plans to integrate the Payara-1 discovery into the third phase of development, which is expected to be sanctioned in 2019.

JDA: Approximately 20% of the capitalized well costs in excess of one year relates to the JDA in the Gulf of Thailand (Hess 50%) where hydrocarbons were encountered in three successful exploration wells drilled in the western part of Block A-18. The operator is currently conducting subsurface evaluations and pre-development planning to facilitate commercial negotiations with the regulator for an extension of the existing gas sales contract to include development of the western part of the Block.