Property, Plant and Equipment

Property, plant and equipment consists of the following (in thousands):



	December 31,
	2015			2014
Oil and natural gas properties
Proved(1)	$	12,529,681		$	11,707,147
Unproved	363,149			290,596
Total oil and natural gas properties	12,892,830			11,997,743
Less accumulated depreciation, depletion and impairment	(11,149,888		)	(6,359,149		)
Net oil and natural gas properties capitalized costs	1,742,942			5,638,594
Land	14,260			16,300
Non-oil and natural gas equipment(2)	373,687			602,392
Buildings and structures(3)	227,673			263,191
Total	615,620			881,883
Less accumulated depreciation and amortization	(123,860		)	(305,420		)
Other property, plant and equipment, net	491,760			576,463
Total property, plant and equipment, net	$	2,234,702		$	6,215,057

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(1)	Includes cumulative capitalized interest of approximately $48.9 million and $38.1 million at December 31, 2015 and 2014, respectively.


(2)	Includes cumulative capitalized interest of approximately $4.3 million at both December 31, 2015 and 2014.


(3)	Includes cumulative capitalized interest of approximately $20.4 million and $17.1 million at December 31, 2015 and 2014, respectively.

Accumulated depreciation, depletion and impairment for oil and natural gas properties includes cumulative full cost ceiling limitation impairment of $8.2 billion and $3.7 billion at December 31, 2015 and 2014, respectively. During the years ended December 31, 2015 and 2014, the Company reduced the net carrying value of its oil and natural gas properties by $4.5 billion and $164.8 million, respectively, as a result of its quarterly full cost ceiling analyses. There was no full cost ceiling impairment during the year ended December 31, 2013. See Note 8 for discussion of impairment of other property, plant and equipment.

The average rates used for depreciation and depletion of oil and natural gas properties were $10.67 per Boe in 2015, $15.00 per Boe in 2014 and $16.81 per Boe in 2013.

During the second and fourth quarters of 2015, the Company classified drilling and oilfield services assets having net book values of approximately $20.0 million and $16.0 million, respectively, as held for sale as a result of the Company’s decisions to discontinue substantially all drilling and oilfield services operations first in the Permian region and then companywide. The Company disposed of certain drilling and oilfield services assets held for sale during the third quarter of 2015 and recorded a loss on sale of assets of $3.5 million for the year ended December 31, 2015. The Company expects to dispose of the remaining assets classified as held for sale at December 31, 2015 prior to the fourth quarter of 2016.

Drilling Carry Commitments

During the years ended December 31, 2014 and 2013, the Company was party to agreements with two co-working interest parties, which contain carry commitments to fund a portion of its future drilling, completing and equipping costs within areas of mutual interest. The Company recorded approximately $205.6 million for Repsol E&P USA, Inc.’s (“Repsol”) carry during the year ended December 31, 2014, and a combined $408.0 million for both Atinum MidCon I, LLC’s (“Atinum”) and Repsol’s drilling carries during the year ended December 31, 2013, which reduced the Company’s capital expenditures for the respective periods. Repsol fully funded its carry commitment in the third quarter of 2014, and the carry commitment from Atinum was fully utilized during the third quarter of 2013.

Under the original agreement with Repsol, the carry commitment could have been reduced if a certain number of wells were not drilled within the area of mutual interest during a twelve-month period and the Company failed to drill such wells following a proposal by Repsol to drill the wells. During 2013, the Company temporarily reduced its rate of drilling activity. As a result, the Company drilled less than the targeted number of wells for such twelve-month period, which resulted in Repsol having a right to propose additional wells. In the second quarter of 2014, the Company and Repsol amended their agreement to eliminate Repsol’s right to propose such additional wells in exchange for a commitment by the Company to drill 484 net wells in the area of mutual interest between January 1, 2014 and May 31, 2015, subject to delays due to factors beyond the Company’s control. Under the terms of the amended agreement, the Company agreed to carry Repsol’s future drilling and completion costs in the amount of $1.0 million for each well of the 484 commitment that it did not drill, up to a maximum of $75.0 million in carry costs. As of May 31, 2015, the Company had drilled 453 net wells under this arrangement. As a result, the Company will carry a portion of Repsol’s drilling and completion costs totaling up to approximately $31.0 million for wells drilled in the future in the area of mutual interest. The Company incurred approximately $16.1 million in costs toward this obligation during the year ended December 31, 2015. Other than the above, the Company has no carry or drilling obligations to Repsol.

Costs Excluded from Amortization

The following table summarizes the costs, by year incurred, related to unproved properties and pipe inventory, which were excluded from oil and natural gas properties subject to amortization at December 31, 2015 (in thousands):



			Year Cost Incurred
	Total		2015		2014		2013		2012 and Prior
Property acquisition	$	362,803	$	197,849	$	70,304	$	14,011	$	80,639
Exploration(1)	34,988		10,698		6,263		17,688		339
Total costs incurred	$	397,791	$	208,547	$	76,567	$	31,699	$	80,978

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(1)	Includes $34.7 million of pipe inventory costs incurred ($10.5 million in 2015, $6.2 million in 2014 and $18.0 million in 2013 and prior years).

The Company expects to complete the majority of the evaluation activities within 10 years from the applicable date of acquisition, contingent on the Company’s capital expenditures and drilling program. In addition, the Company’s internal engineers evaluate all properties on at least an annual basis.