The intangible assets of the Group comprise software, gas processing rights of the NWS Project, marketing transportation and storage contracts, drilling rig contracts and seismic data usage rights. Intangible assets with finite lives are carried at cost, less accumulated amortization and accumulated impairment losses. The cost of intangible assets acquired in a business combination is the fair value as at the date of acquisition. Intangible assets with finite lives except for gas processing rights, are amortized on the straight-line basis over the useful economic life and assessed for impairment whenever there is an indication that the intangible asset may be impaired. The amortization period and the amortization method for an intangible asset with a finite useful life are reviewed at least at each financial year end.
The intangible assets regarding software have been amortized on the straight-line basis over their respective useful lives. The intangible asset regarding the gas processing rights has been amortized upon the commercial production of the liquefied natural gas on a unit-of-production basis over the total proved reserves of the relevant asset. The intangible assets regarding the marketing transportation and storage contracts and drilling rig contracts are amortized over the life of the contracts on the straight-line basis. The intangible assets related to the seismic data usage rights are amortized over the estimated useful life of the seismic data.