text: **Depreciation and amortisation expense, including depletion.**Our depreciation and amortisation expense increased by 
  $49.4 million (136.3%) to $85.6 million for the year ended 31 December 2014 from $36.2 million for the prior year and 
  increased $4.58 per Boe to $38.15 per Boe from $33.57 per Boe. The increase reflects our increase in production (107.9%), an 
  increase in our asset base subject to amortisation as a result of our acquisition and development activity, and increased 
  completion costs caused by high-demand for completion services and a shortage of trucks able to transport frac sand and 
  resultant higher trucking rates. 
  
  **General and administrative expenses.**General and administrative expenses per Boe decreased by 51.2% to $6.92 for the year 
  ended 31 December 2014 as compared to $14.18 per Boe for the prior year. The decrease in general and administrative 
  expenses per Boe is driven by increased production levels diluting fixed general and administrative costs. 
  
  **Impairment expense.**The Company recorded impairment expense of $71.2 million for the year ended 31 December 2014 on 
  the Company’s development and production assets that are located in Greater Anadarko and the Eagle Ford as the recoverable 
  amount was less than the carrying value primarily as a result of lower commodity pricing. No impairment was necessary on 
  the Company’s exploration and evaluation assets. See Note 17 of the Notes to the Consolidated Financial Statements for 
  further discussion. 
  
  **Exploration expense.**The Company incurred exploration expense of $10.9 million for the year ended 31 December 2014 on 
  three unsuccessful exploratory wells in the Anadarko Basin. The Company did not drill any unsuccessful exploratory wells in 
  the prior year. 