6. Capitalized Exploratory Well Costs

The following table discloses the net changes in capitalized exploratory well costs pending determination of proved reserves for the nine months ended September 30, 2011 (in millions):


Balance at January 1	$	1,783
Additions to capitalized exploratory well costs pending the determination of proved reserves		534
Reclassification to wells, facilities, and equipment based on the determination of proved reserves		(168	)
Capitalized exploratory well costs charged to expense		(70	)
Dispositions		(12	)

Balance at end of period	$	2,067

Capitalized exploratory well costs charged to expense in the preceding table excludes $132 million of exploratory well costs which were incurred and subsequently expensed in 2011. Capitalized exploratory well costs greater than one year old after completion of drilling were $1,320 million at September 30, 2011. Approximately 38% of the capitalized well costs in excess of one year relates to the Pony project in the deepwater Gulf of Mexico, where development planning is progressing with sanction targeted for 2012. Approximately 30% relates to Block WA-390-P, offshore Western Australia, where further drilling and other appraisal and commercial activities are ongoing. Approximately 20% relates to Area 54, offshore Libya, where force majeure has been declared following the civil unrest in Libya. The remainder of the capitalized well costs in excess of one year relates to projects where further drilling is planned or development planning and other assessment activities are ongoing to determine the economic and operating viability of the projects.