Capitalized overhead. For the year ended December 31, 2012, additions to property, plant and equipment included internal overhead costs of $3.4 million (December 31, 2011 - $4.6 million).
Depletion, depreciation and impairment charges. Depletion and depreciation, impairment of property, plant and equipment, and any reversal thereof, are recognized as separate line items in the consolidated statements of operations (see note 7). The Company included $145.3 million in future development costs and $4.5 million in abandonment costs related to undeveloped reserves (December 31, 2011 - $264.9 million, $11.0 million respectively).
Sale of property, plant and equipment. For the year ended December 31, 2012, the Company sold interests in 17 properties for total consideration of $73.9 million (December 31, 2011 - $11.6 million). See note 14.
7. IMPAIRMENT LOSS AND IMPAIRMENT REVERSAL
In 2011, there were indicators of impairment and reversal of impairment for the Deep Gas, Shallow Gas and Non-core CGUs due to changes in forecasted commodity prices used by the Company's independent qualified reserves evaluators when compared to December 31, 2010. Accordingly, the Company tested those CGUs for impairment or reversal and determined that the aggregate carrying value of these CGUs was $35.2 million (net of impairment reversals of $9.7 million recorded for the Deep Gas CGU) higher than the recoverable amount and impairments were recorded ($2.6 million - Deep Gas CGU; $25.8 million - Shallow Gas CGU; and $6.8 million - Non-core CGU.)
The recoverable amounts of the CGUs were estimated based on the fair value less costs to sell (see notes 4 and 5). Carrying amounts are calculated as the net book value of property, plant and equipment less provisions for decommissioning obligations.
In 2012, declines in forecasted commodity prices were indicators of impairment. Forecasted commodity prices at December 31, 2012 declined between 14% and 18% for natural gas and between 4% and 16% for light, sweet crude oil when compared to December 31, 2011.
The following table shows the differences in the future natural gas commodity prices used by the Company's independent qualified reserves evaluators at December 31, 2012 compared to December 31, 2011:
Light, Sweet Crude Edmonton ($Cdn/bbl) AECO Gas Price ($Cdn/MMBtu) December December December DecemberYear 31, 2012 31, 2011 Difference 31, 2012 31, 2011 Difference2013 85.00 101.02 (16.02) 3.38 4.13 (0.75)2014 91.50 101.02 (9.52) 3.83 4.59 (0.76)2015 94.00 101.02 (7.02) 4.28 5.05 (0.77)2016 96.50 101.02 (4.52) 4.72 5.51 (0.79)2017 96.50 101.02 (4.52) 4.95 5.97 (1.02)2018 96.50 102.40 (5.90) 5.22 6.21 (0.99)2019 97.54 104.47 (6.93) 5.32 6.33 (1.01)2020 99.51 106.58 (7.07) 5.43 6.46 (1.03)2021 101.52 108.73 (7.21) 5.54 6.58 (1.04)----------------------------------------------------------------------------
In the second quarter of 2012, the Company tested its gas-weighted CGUs for impairment and determined that the aggregate carrying value of these CGUs was $20 million higher than the recoverable amounts and impairments were recorded ($13 million for the Shallow Gas CGU and $7 million for the Deep Gas CGU). In the third and fourth quarters of 2012, the Company tested all of its CGUs for impairment and determined that no additional charges for impairment were required.
