divide by 2, i.e., (25 X 26) : 2 = 325. The first year's full depreciation deduction would be 25/325ths; the second year's would be 24/325ths, etc., of the cost of the property (From AGA)
George E. King Engineering, 5000 Oilfield Terms: A Glossary of Petroleum Engineering Terms, Abbreviations and Acronyms, US 2010. http://gekengineering.com/Downloads/Free_Downloads /Glossary_of_Petroleum_Engineering_Terms_25_August _2010.pdf, (Oil - Amer) {593}