text: When approval of commercial development of a discovered oil or gas field occurs, the accumulated costs for the 
  relevant area of interest are transferred to development and production assets. The costs of developed and 
  producing assets are amortised over the life of the area according to the rate of depletion of the proved and probable 
  developed reserves. The costs associated with the undeveloped acreage are not subject to depletion. 
  
  The carrying amounts of the Group’s exploration and evaluation assets are reviewed at each reporting date, in 
  conjunction with the impairment review process referred to in Note 1(f), to determine whether any of impairment 
  indicators exists. Impairment indicators could include i) tenure over the licence area has expired during the period 
  or will expire in the near future, and is not expected to be renewed, ii) substantive expenditure on further exploration 
  for and evaluation of mineral resources in the specific area is not budgeted or planned, iii) exploration for and 
  evaluation of resources in the specific area have not led to the discovery of commercially viable quantities of 
  resources, and the Group has decided to discontinue activities in the specific area, or iv) sufficient data exist to 
  indicate that although a development is likely to proceed, the carrying amount of the exploration and evaluation 
  asset is unlikely to be recovered in full from successful development or from sale. Where an indicator of impairment 
  exists, a formal estimate of the recoverable amount is made and any resulting impairment loss is recognized in the 
  income statement. 