4. Capitalized Exploratory Well Costs

The following table discloses the net changes in capitalized exploratory well costs pending determination of proved reserves for the six months ended June 30, 2015 (in millions):

Balance at January 1	$	1,416
Additions to capitalized exploratory well costs pending the determination of proved reserves		281
Reclassifications to wells, facilities and equipment based on the determination of proved reserves		(72	)
Capitalized exploratory well costs charged to expense		(120	)
Balance at June 30, 2015	$	1,505

Capitalized exploratory well costs charged to expense in the preceding table primarily relate to the Dinarta Block in the Kurdistan Region of Iraq following the decision of the Corporation and its partner in March 2015 to cease further drilling activity in the region. In addition, the Corporation expensed $56 million of exploratory well costs incurred during 2015 that are not reflected in the preceding table.

Capitalized exploratory well costs greater than one year old after completion of drilling were $1,247 million at June 30, 2015. Approximately 70% of the capitalized well costs in excess of one year relates to Block WA-390-P, offshore Western Australia, where development planning and commercial activities for the Corporation’s natural gas discoveries are ongoing. In December 2014, the Corporation executed a non-binding letter of intent with the North West Shelf (NWS), a third party joint venture with existing natural gas processing and liquefaction facilities. Successful execution of binding agreements with NWS is necessary before the Corporation can execute a gas sales agreement and sanction development of the project. Approximately 30% of the capitalized well costs in excess of one year relates to offshore Ghana, where the Corporation has drilled seven successful exploration wells. Appraisal plans for the seven wells on the block were submitted to the Ghanaian government in June 2013 for approval. Four of the plans were approved and discussions continue with the government on the three remaining appraisal plans. In 2014, the Corporation completed a three well appraisal program in Ghana. Well results continue to be evaluated and development planning is progressing.