Note 7. Capitalized Exploratory Well Costs

We capitalize exploratory well costs until a determination is made that the well has found proved reserves or is deemed noncommercial. If a well is deemed to be noncommercial, the well costs are immediately charged to exploration expense.

Changes in capitalized exploratory well costs are as follows and exclude amounts that were capitalized and subsequently expensed in the same period:

	Year Ended December 31,
	2011			2010			2009
(millions)
Capitalized Exploratory Well Costs, Beginning of Period	$	466		$	463		$	522
Additions to Capitalized Exploratory Well Costs Pending Determination of Proved Reserves		322			161			153
Reclassified to Proved Oil and Gas Properties Based on Determination of Proved Reserves		(55	)		(155	)		(205	)
Capitalized Exploratory Well Costs Charged to Expense		(37	)		(3	)		(7	)
Capitalized Exploratory Well Costs, End of Period	$	696		$	466		$	463

The following table provides an aging of capitalized exploratory well costs (suspended well costs) based on the date that drilling commenced and the number of projects for which exploratory well costs have been capitalized for a period greater than one year since the commencement of drilling:

	December 31,
	2011		2010		2009
(millions)
Exploratory Well Costs Capitalized for a Period of One Year or Less	$	318	$	166	$	175
Exploratory Well Costs Capitalized for a Period Greater Than One Year Since Commencement of Drilling		378		300		288
Balance at End of Period	$	696	$	466	$	463
Number of Projects with Exploratory Well Costs That Have Been Capitalized for a Period Greater Than One Year Since Commencement of Drilling		9		9		5

The following table provides a further aging of those exploratory well costs that have been capitalized for a period greater than one year since the commencement of drilling as of December 31, 2011:

			Suspended Since
	Total		2010		2009		2008 & Prior
(millions)
Country/Project
Offshore Equatorial Guinea
Blocks O and I	$	112	$	6	$	19	$	87
Offshore Cameroon
YoYo		40		2		2		36
Offshore Israel
Leviathan		41		41		-		-
Dalit		22		1		21		-
Deepwater Gulf of Mexico
Gunflint		59		3		6		50
Deep Blue		73		54		19		-
North Sea
Selkirk		23		1		1		21
Other
2 projects of $10 million or less each		8		8		-		-
Total	$	378	$	116	$	68	$	194

Blocks O and I Blocks O and I are crude oil, natural gas and natural gas condensate discoveries. During the second quarter of 2011, we drilled the successful Diega appraisal well which encountered both crude oil and natural gas. We have drilled two sidetracks, each of which encountered hydrocarbons. We are currently finalizing our appraisal of Diega and are evaluating regional development scenarios.

YoYo YoYo is a 2007 natural gas and condensate discovery. During 2011 we acquired and processed additional 3-D seismic information and are evaluating for future drilling potential.

Leviathan Leviathan is a 2010 natural gas discovery. We are continuing to evaluate the discovery with the successful drilling of the Leviathan-3 appraisal well. In January 2012, we resumed drilling at the Leviathan-1 well in order to evaluate two additional intervals for the existence of crude oil. Results from these deeper tests are expected during the first half 2012. We will require an additional one or two appraisal wells to further define Leviathan's boundaries in order to determine the best development option including subsea tieback to existing shallow water platform, semi-submersible platform, FPSO, or floating LNG.

Dalit Dalit is a 2009 natural gas discovery. We are currently working with our partners on a cost-effective development plan.

Gunflint Gunflint (Mississippi Canyon Block 948) is a 2008 crude oil discovery. Our plans to drill two or three appraisal wells in 2011 were delayed by the post-Deepwater Moratorium permitting process. In October 2011, we received a drilling permit and in December 2011 we resumed drilling at Gunflint. We currently anticipate drilling up to three appraisal wells to fully evaluate the extent of the reservoir. We are also reviewing host platform options including: subsea tieback to an existing third-party host and construction of a new facility. If we are able to connect to an existing third-party host, the project could have an accelerated completion schedule, thereby potentially absorbing time lost due to the drilling delay caused by the Deepwater Moratorium and permit-related delay.

Deep Blue Deep Blue (Green Canyon Block 723) was a significant test well, which began drilling during 2009. When the Deepwater Moratorium was announced in May 2010, we were required to suspend side track drilling activities at the Deep Blue prospect. In November 2011 we announced that we have finished the well and found additional hydrocarbons in high quality reservoirs. During first quarter of 2012, we will be completing additional analysis of the data from the side track well.

Selkirk The Selkirk project is located in the UK sector of the North Sea. Capitalized costs to date primarily consist of the cost of drilling an exploratory well. We are currently working with our partners on a cost-effective development plan, including selection of a host facility.