(f) Depreciation, Depletion, Amortization and Accretion
Oil and Natural Gas Properties
Depreciation, depletion, amortization and accretion (“DD&A”) of capitalized costs of proved oil and natural gas properties is computed using the unit-of-production method on a field level basis using total estimated proved reserves. The reserve base used to calculate DD&A for leasehold acquisition costs and the cost to acquire proved properties is the sum of proved developed reserves and proved undeveloped reserves. The reserve base used to calculate DD&A for drilling, completion and well equipment costs, which include development costs and successful exploration drilling costs, includes only proved developed reserves. DD&A expense relating to proved oil and natural gas properties, including accretion expense, totaled approximately $42.4 million and $38.0 million for the three months ended June 30, 2020 and 2019, respectively, and $86.1 million and $67.5 million for the six months ended June 30, 2020 and 2019, respectively, and is included in depreciation, depletion, amortization and accretion expense in the Condensed Consolidated Statements of Operations and Comprehensive Income (Loss).
Other Property and Equipment
Depreciation with respect to other property and equipment is calculated using straight-line methods based on expected lives of the individual assets or groups of assets ranging from five to 40 years. Depreciation totaled approximately $0.4 million and $0.6 million for the three months ended June 30, 2020 and 2019, respectively, and $0.8 million and $1.0 million for the six months ended June 30, 2020 and 2019, respectively, and is included in depreciation, depletion, amortization and accretion expense in the Condensed Consolidated Statements of Operations and Comprehensive Income (Loss).
(g) Impairment of Long-Lived Assets
The Company reviews its long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. If it is determined that an asset’s estimated future cash flows will not be sufficient to recover its carrying amount, an impairment charge will be recorded to reduce the carrying amount for that asset to its estimated fair value if such carrying amount exceeds the fair value.
The review for impairment of the Company’s oil and gas properties is performed by determining whether the historical cost of proved and unproved properties less the applicable accumulated DD&A and abandonment is less than the estimated expected undiscounted future cash flows. The expected future cash flows are estimated based on the Company’s plans to continue to produce and develop proved reserves and a risk-adjusted portion of probable reserves. Expected future cash flow from the sale of production of reserves is calculated based on estimated future prices. The Company estimates prices based upon current contracts in place, adjusted for basis differentials and market-related information, including published futures prices. The estimated future level of production is based on assumptions surrounding future prices and costs, field decline rates, market demand and supply and the economic and regulatory climates. If the carrying value exceeds the expected future cash flows, an impairment loss is recognized for the difference between the estimated fair market value (as determined by discounted future cash flows) and the carrying value of the assets. There were no impairments of proved properties held and used for the three months ended June 30, 2020 and 2019 or for the six months ended June 30, 2020 and 2019. The Company recorded impairment of proved properties held for sale during the six months ended June 30, 2020. See Note 5- Assets Held for Sale and Discontinued Operations.
When an impairment charge is recognized it represents a significant Level 3 measurement in the fair value hierarchy. The primary input used is the
Company’s forecasted discount net cash flows.
The determination of oil and natural gas reserve estimates is a subjective process, and the accuracy of any reserve estimate depends on the quality of available data and the application of engineering and geological interpretation and judgment. Estimates of economically recoverable reserves and future net cash flows depend on a number of variable factors and assumptions that are difficult to predict and may vary considerably from actual results.
Unproved oil and natural gas properties are periodically assessed for impairment by considering future drilling and exploration plans, results of exploration activities, commodity price outlooks, planned future sales and expiration of all or a portion of the properties. An impairment charge is recorded if conditions indicate the Company will not explore the acreage prior to expiration of the applicable leases. The Company recorded impairment charges of unproved oil and gas properties related to lease expirations of approximately $8.6 million and $12.4 million for the three months ended June 30, 2020 and 2019, respectively, and $19.4 million and $22.0 million for the six months ended June 30, 2020 and 2019, respectively. These costs are included in exploration expense in the Condensed Consolidated Statements of Operations and Comprehensive Income (Loss).
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