Asset Impairments

Pre-tax (non-cash) asset impairment charges were as follows:



	Year Ended December 31,
	2012		2011		2010
(millions)
Piceance (Onshore US)	$	39	$	487	$	—
South Raton (Deepwater Gulf of Mexico)	34		—		—
Mari-B, Noa, Pinnacles (Offshore Israel)	31		—		—
East Texas (Onshore US)	—		128		—
Tri-State (Onshore US)	—		121		—
Iron Horse (Onshore US)	—		15		89
Other Onshore US Properties	—		6		—
New Albany Shale (Onshore US)	—		—		19
Noa/Noa South (Offshore Israel)	—		—		25
Raton (Deepwater Gulf of Mexico)	—		—		6
Main Pass (Gulf of Mexico Shelf)	—		—		5
Total	$	104	$	757	$	144

2012 Asset Impairments Due to recent declines in realized natural gas prices associated with our Piceance development, onshore US, and recent declines in near-term crude oil prices associated with our South Raton development in the deepwater Gulf of Mexico, we determined that their carrying amounts were not recoverable from future cash flows and, therefore, were impaired. In addition, due to end-of-field life declines in production of our Mari-B, Noa and Pinnacles fields, offshore Israel, we determined that the carrying amount was not recoverable from future cash flows and, therefore, was impaired. The assets were written down to their estimated fair values, which were determined using discounted cash flow models. The discounted cash flow models included management’s estimates of future oil and gas production, commodity prices based on forward commodity price curves or contract prices as of the date of the estimate, operating and development costs, and discount rates.

2011 Asset Impairments Due to a significant decline in spot and five-year forward natural gas prices, specifically during the fourth quarter of 2011, as well as field performance, we determined that the carrying amounts of certain of our onshore US developments were not recoverable from future cash flows and, therefore, were impaired. The assets were written down to their estimated fair values, which were determined using discounted cash flow models, as described above.

2010 Asset Impairments Due to declines in natural gas prices and recent drilling results, we determined that the carrying amount of our onshore US development at Iron Horse was not recoverable from future cash flows and, therefore, was impaired. We also recorded impairments of our non-core, New Albany Shale assets which had been reclassified to held-for-sale; our deepwater Gulf of Mexico development at Raton, primarily due to declines in natural gas prices; a Gulf of Mexico shelf asset; and our investment in the Noa/Noa South development, offshore Israel. At December 31, 2010, we believed that it was less likely that Noa would be pursued for development due to near-term capability at the Mari-B field and the longer-term outlook from our discoveries at Tamar and Leviathan. During 2011, due to unexpected natural gas supply disruptions into Israel, we decided to develop Noa/Noa South. The Iron Horse, Raton and Gulf of Mexico shelf assets were written down to their estimated fair values, which were determined using discounted cash flow models, as described above. The New Albany shale assets were written down to anticipated sales proceeds less costs to sell.

See also Note 15. Fair Value Measurements and Disclosures.