the NYMEX pricing. The EXCO/HGI JV believes the NYMEX futures contracts reflect an independent proxy for fair value. Management's internal valuation model demonstrated that the fair value of these acquired oil and natural gas properties clearly exceeded the calculated ceiling test limitation as of June 30, 2013 beyond a reasonable doubt.
The EXCO/HGI JV recognizes that, due to the volatility associated with oil and natural gas prices, a downward trend in market prices could occur. If such a case were to occur and is deemed to be other than a temporary trend, the EXCO/HGI JV would assess these acquisitions for impairment during the requested exemption period. Further, if the EXCO/HGI JV cannot demonstrate that fair value exceeds the calculated ceiling test limitation during the requested exemption periods prior to issuance of its financial statements, the EXCO/HGI JV will recognize impairment related to these acquisitions.
The ceiling test calculation is based upon estimates of proved reserves. There are numerous uncertainties inherent in estimating quantities of proved reserves, in projecting the future rates of production and in the timing of development activities. The accuracy of any reserve estimate is a function of the quality of available data and of engineering and geological interpretation and judgment. Results of drilling, testing and production subsequent to the date of the estimate may justify revision of such estimate. Accordingly, reserve estimates are often different from the quantities of oil and natural gas that are ultimately recovered.
Gas gathering assets
Gas gathering assets are capitalized at cost and depreciated on a straight line basis over their estimated useful lives of up to 14 years.
Deferred abandonment and asset retirement obligations
The EXCO/HGI JV applies FASB ASC 410-20, Asset Retirement and Environmental Obligations ("ASC 410-20"), to account for estimated future plugging and abandonment costs. ASC 410-20 requires legal obligations associated with the retirement of long-lived assets to be recognized at their estimated fair value at the time that the obligations are incurred. Upon initial recognition of a liability, that cost is capitalized as part of the related long-lived asset and allocated to expense over the useful life of the asset. The EXCO/HGI JV's asset retirement obligations primarily represent the present value of the estimated amount it will incur to plug, abandon and remediate proved producing properties at the end of their productive lives, in accordance with applicable state laws.
The EXCO/HGI JV's asset retirement obligations are determined using discounted cash flow methodologies based on inputs that are not readily available in public markets. The EXCO/HGI JV has no assets that are legally restricted for purposes of settling asset retirement obligations.
Revenue recognition and gas imbalances
The EXCO/HGI JV uses the sales method of accounting for oil and natural gas revenues. Under the sales method, revenues are recognized based on actual volumes of oil and natural gas sold to purchasers. Gas imbalances at June 30, 2013 were not significant.
Gathering and transportation
The EXCO/HGI JV generally sells oil and natural gas under two types of agreements which are common in the industry. Both types of agreements include a transportation charge. One is a net-back arrangement, under which the EXCO/HGI JV sells oil or natural gas at the wellhead and collects a price, net of the transportation incurred by the purchaser. In this case, The EXCO/HGI JV records sales at the price received from the purchaser, net of the transportation costs. Under the other arrangement, the EXCO/HGI JV sells oil or natural gas at a specific delivery point, pays transportation to a third party and receives proceeds from the purchaser with no transportation deduction. In this case, the EXCO/HGI JV records the transportation cost as gathering and transportation expense. Due to these two distinct selling arrangements, The EXCO/HGI JV's computed realized prices, before the impact of derivative financial instruments, includes revenues which are reported under two separate bases.
Overhead reimbursement fees
The EXCO/HGI JV has classified fees from overhead charges billed to working interest owners, including itself, as a reduction of general and administrative expenses in the accompanying Condensed Consolidated Statements of Operations. The EXCO/HGI JV's share of these charges was $1.8 for the three months ended June 30, 2013,
