The following table discloses the net changes in capitalized exploratory well costs pending determination of proved reserves during the three months ended March 31, 2019 (in millions):

Balance at January 1, 2019	$	418
Additions to capitalized exploratory well costs pending the determination of proved reserves		48
Balance at March 31, 2019	$	466

Capitalized exploratory well costs capitalized for greater than one year following completion of drilling were $309 million at March 31, 2019 and primarily related to:

Guyana: Approximately 45% of the capitalized well costs in excess of one year relates to the Liza-4, Pacora-1, Payara-1, Payara-2, Ranger-1 and Snoek-1 wells on the Stabroek Block, offshore Guyana (Hess 30%), where hydrocarbons were encountered. The operator plans to integrate the Liza-4 discovery into the second phase of development, which is expected to commence production by mid-2022. The operator plans to integrate the Pacora-1, Payara-1 and Payara-2 discoveries into the third phase of development, which is expected to commence production as early as 2023. The Snoek discovery is expected to produce into the Liza Phase 1 floating, production storage and offloading (FPSO) vessel under a subsequent phase of development, and the operator is planning further drilling at the Ranger discovery.

Gulf of Mexico: Approximately 40% of the capitalized well costs in excess of one year relates to the appraisal of the northern portion of the Shenzi Field (Hess 28%) in the Gulf of Mexico, where hydrocarbons were encountered in the fourth quarter of 2015. Following exploration and appraisal drilling activities completed by the operator in prior years on adjacent blocks to the north of our Shenzi blocks, the operator is planning to acquire 3D seismic in 2019 for use in development planning of the northern portion of the Shenzi Field.

JDA: Approximately 10% 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 has submitted a development plan concept to the regulator to facilitate commercial negotiations for an extension of the existing gas sales contract to include development of the western part of the Block.

Malaysia: Approximately 5% of the capitalized well costs in excess of one year relates to the North Malay Basin, offshore Peninsular Malaysia (Hess 50%), where hydrocarbons were encountered in one successful exploration well drilled in the fourth quarter of 2015. In 2018, we completed four exploration wells and are conducting subsurface evaluations for consideration in future phases of field development.