ASSET IMPAIRMENT

Impairments recognized by Energen are presented below:



Years ended December 31, (in thousands)	2017		2016		2015
Permian Basin properties
Central Basin Platform	$	1,096	$	187,043	$	484,848
Delaware Basin	—		21,288		607,303
Midland Basin	—		—		—
San Juan Basin properties	—		7,519		133,055
Permian Basin unproved leasehold properties	575		4,762		29,168
San Juan Basin unproved leasehold properties	—		40		37,934
Total asset impairments	$	1,671	$	220,652	$	1,292,308

Non-cash impairment writedowns are reflected in asset impairment in the consolidated statements of operations.

Permian Basin: During 2017, Energen recognized non-cash impairment writedowns in the Permian Basin of $1.1 million to adjust the carrying amount of these proved properties to their fair value.

During the first quarter of 2016, Energen recognized non-cash impairment writedowns in the Permian Basin of $208.3 million to adjust the carrying amount of these properties to their fair value. We estimate future discounted cash flows in determining fair value using commodity assumptions, which are based on the commodity price curve for five years and then escalated at 3 percent through our assumed price cap. Our commodity price assumptions declined in the first quarter of 2016 by approximately 5 percent for oil and 4 percent for natural gas in comparable periods.

For 2015, Energen recognized non-cash impairment writedowns on certain properties in the Permian Basin of $1,092.2 million to adjust the carrying amount of these properties to their fair value primarily due to commodity price declines. We estimate future discounted cash flows in determining fair value using commodity assumptions, which are based on the commodity price curve for five years and then escalated at 3 percent through our assumed price cap.

In 2017, Energen recognized unproved leasehold writedowns primarily on Permian Basin oil properties of $0.6 million. During 2016, Energen recognized unproved leasehold writedowns primarily on Permian Basin oil properties in the Delaware Basin and the Central Basin Platform of $4.8 million. Energen recognized unproved leasehold writedowns primarily on Permian Basin oil properties in the Delaware Basin of $29.2 million in 2015.

San Juan Basin: During the first quarter of 2016, Energen recognized non-cash impairment writedowns on held for sale properties in the San Juan Basin of $7.5 million to adjust the carrying amount of these properties to their fair value.

Energen recognized non-cash impairment writedowns on properties in the San Juan Basin of $133.1 million during 2015 to adjust the carrying amount of these properties to their fair value based on expected future discounted cash flows. During 2015, Energen recognized unproved leasehold writedowns on San Juan Basin properties of $37.9 million.