text: Management has made the following judgements, which have the most significant effect on the amounts recognised 
  in the consolidated financial statements. 
  
  **Estimates of reserve quantities**
  The estimated quantities of hydrocarbon reserves reported by the Group are integral to the calculation of 
  amortisation (depletion) and to assessments of possible impairment of assets. Estimated reserve quantities are 
  based upon interpretations of geological and geophysical models and assessment of the technical feasibility and 
  commercial viability of producing the reserves. Management prepares reserve estimates which conform to 
  guidelines prepared by the Society of Petroleum Engineers. Management also prepares reserve estimates under SEC 
  guidelines. Reserve estimates conforming to the guidelines prepared by the Society of Petroleum Engineers are 
  utilized for accounting purposes. These assessments require assumptions to be made regarding future development 
  and production costs, commodity prices, exchange rates and fiscal regimes. The estimates of reserves may change 
  from period to period as the economic assumptions used to estimate the reserves can change from period to period, 
  and as additional geological data is generated during the course of operations. 