Note 5. Asset Impairments

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



	Year Ended December 31,
(millions)	2015		2014		2013
Onshore US	$	—	$	42	$	39
Deepwater Gulf of Mexico	158		350		—
Equatorial Guinea	339		—		—
Eastern Mediterranean	36		14		47
North Sea	—		94		—
Total	$	533	$	500	$	86

2015 Asset Impairments During 2015, certain deepwater Gulf of Mexico, Eastern Mediterranean and Equatorial Guinea properties were written down to their estimated fair values using a discounted cash flow model. The cash flow model included management’s estimates of future crude oil and natural 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. Impairment charges of $481 million resulted from reductions in the forward crude oil prices as of December 31, 2015. In addition, we recorded approximately $47 million of impairment primarily related to revisions in expected field abandonment and other costs for deepwater Gulf of Mexico and Eastern Mediterranean properties.

During fourth quarter 2015, we executed an agreement to divest our interest in the Alon A and Alon C offshore Israel licenses, which include the Karish and Tanin fields. As a result, these assets were written down to expected proceeds less costs to sell, resulting in a $5 million impairment.

2014 Asset Impairments As a result of declining crude oil prices at the end of 2014, we recorded impairment charges of $250 million related to certain onshore US and deepwater Gulf of Mexico properties.

During 2014, South Raton in the deepwater Gulf of Mexico was shut-in due to mechanical issues; therefore, we recorded additional impairment charges of $74 million for South Raton in fourth quarter 2014.

Additionally, the asset carrying values of certain crude oil and natural gas properties in the deepwater Gulf of Mexico and offshore Israel increased when we recorded associated increases in asset retirement obligations. We determined that the recorded carrying values of some of these assets were not recoverable from future cash flows and recorded impairment expense of $51 million.

During third quarter 2014, we reclassified certain non-core properties as assets held for sale. The assets were written down to expected proceeds less costs to sell, resulting in a $31 million impairment.

In March 2014, the operator of the MacCulloch North Sea field notified the working interest owners that expected field abandonment costs would be higher than originally projected, and that field abandonment would occur sooner than anticipated. As a result of this new information, we adjusted the asset retirement obligation to reflect the updated estimate of abandonment costs and timing. We assessed the asset for impairment and determined that it was impaired.

2013 Asset Impairments We recorded impairments of the Mari-B field, due to natural field decline, and certain non-core, onshore US properties upon reclassification to assets held for sale. The Mari-B field was written down to its estimated fair value using a discounted cash flow model, as described above. The fair values of onshore US assets held for sale were based on anticipated sales proceeds less costs to sell.

See Note 13. Fair Value Measurements and Disclosures.