Unevaluated Property

12 Months Ended

Dec. 31, 2019

Property, Plant and Equipment [Abstract]

Note 5. Unevaluated Property

A summary of the unevaluated property costs excluded from oil and natural gas properties being amortized at December 31, 2019, and the year in which the costs were incurred follows:



	December 31, 2019
	Costs Incurred During:
In thousands	2019		2018		2017		2016 and Prior		Total
Property acquisition costs	$	—	$	—	$	8,527	$	572,930	$	581,457
Exploration and development	3,522		1,862		3,175		108,268		116,827
Capitalized interest	31,489		27,013		23,134		92,990		174,626
Total	$	35,011	$	28,875	$	34,836	$	774,188	$	872,910

Our property acquisition costs for 2016 and prior were primarily related to the fair value allocated to the purchase of interests in the Cedar Creek Anticline (“CCA”) and Hartzog Draw, as well as CO₂ tertiary potential at Conroe Field. Exploration and development costs shown as unevaluated properties are primarily associated with our tertiary oil fields that are under development but did not have proved reserves at December 31, 2019. The most significant development costs incurred during each period relate to development in preparation for the CO₂ floods at Webster, Conroe, and CCA fields. We have not yet recognized proved tertiary reserves in these fields.

Costs are transferred into the amortization base on an ongoing basis as projects are evaluated and proved reserves established or impairment determined. We review the excluded properties for impairment at least annually. We currently estimate that evaluation of the majority of these properties and the inclusion of their costs in the amortization base is expected to be completed

within five to ten years. Until we are able to determine whether there are any proved reserves attributable to the above costs, we are not able to assess the future impact on the amortization rate of the full cost pool.