
	2023		2022

	(In millions)
Exploration and Production
Unproved properties	$	103	$	149
Proved properties	2,660		2,660
Wells, equipment and related facilities	29,159		25,182
	31,922		27,991
Midstream	4,819		4,571
Corporate and Other	30		30
Total — at cost	36,771		32,592
Less: Reserves for depreciation, depletion, amortization and lease impairment	19,339		17,494
Property, Plant and Equipment — Net	$	17,432	$	15,098

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:


	2023		2022		2021

	(In millions)
Balance at January 1	$	886	$	681	$	459
Additions to capitalized exploratory well costs pending the determination of proved reserves	257		298		222
Reclassifications to wells, facilities and equipment based on the determination of proved reserves	(133)		(93)		—
Capitalized exploratory well costs charged to expense	(58)		—		—

Balance at December 31	$	952	$	886	$	681
Number of Wells at December 31	43		43		35

During the three years ended December 31, 2023, additions to capitalized exploratory well costs primarily related to drilling at the Stabroek Block (Hess 30%), offshore Guyana. At December 31, 2023, 36 exploration and appraisal wells on the Stabroek Block, with a total cost of $841 million, were capitalized pending determination of proved reserves. Other additions to capitalized exploratory well costs in 2023 include the Pickerel-1 exploration well (Hess 100%) in the Gulf of Mexico on Mississippi Canyon Block 727.

Other additions to capitalized exploratory wells costs in 2022 include the Huron-1 well (Hess 40%) in the Gulf of Mexico, and the Zanderij-1 well on Block 42 (Hess 33%), offshore Suriname.

Reclassifications to wells, facilities and equipment based on the determination of proved reserves in 2023 resulted from the sanction of the Uaru Field development, the fifth sanctioned project on the Stabroek Block, and the Pickerel-1 exploration well in the Gulf of Mexico. In 2022, reclassifications to wells, facilities and equipment resulted from the sanction of the Yellowtail Field development, the fourth sanctioned project on the Stabroek Block.

Capitalized exploratory well costs charged to expense in 2023 of $58 million primarily relate to the Huron-1 well in the Gulf of Mexico. In the fourth quarter of 2023, we, along with our partners, decided not to appraise the discovery given other available opportunities and the limited time remaining on the leases. The preceding table excludes well costs incurred and expensed during 2023 of $89 million (2022: $56 million; 2021: $11 million).

Exploratory well costs capitalized for greater than one year following completion of drilling were $728 million at December 31, 2023, separated by year of completion as follows (in millions):

Guyana: 87% of the capitalized well costs in excess of one year relate to successful exploration and appraisal wells where hydrocarbons were encountered on the Stabroek Block (Hess 30%). In October 2023, the operator submitted a plan for the Whiptail development project, the sixth development project on the Stabroek Block, to the Government of Guyana for approval. The operator also plans further appraisal drilling on the block and is conducting pre-development planning for additional phases of development.

Suriname.: 6% of the capitalized well costs in excess of one year relates to the Zanderij-1 well on Block 42 (Hess 33%). Exploration and appraisal activities are ongoing.

JDA: 5% of the capitalized well costs in excess of one year relates to the JDA (Hess 50%) 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 has submitted a development plan concept to the regulator to facilitate ongoing commercial negotiations for an extension of the existing gas sales contract to include development of the western part of the block.

Malaysia: 2% of the capitalized well costs in excess of one year relates to North Malay Basin (Hess 50%), offshore Peninsular Malaysia, where hydrocarbons were encountered in two successful exploration wells. Pre-development studies are ongoing.