b'(X US$ 1,000) Decommissioning productionDecommissioning Decommissioning Environmental Other Totalfield & facilities Refinery Power Plant Risk ProvisionsAt January 1, 2017 40,062 5,539 98 2,588 1,600 49,887Arising during the year- - -1571,758 1,915Write-backofunusedprovisions - - - - -Discountrateadjustment&imputedinterest 35,242 2,776 101 36 - 38,155Unwinding of discount 4,118 569 10 - - 4,697Utilisation - - - - (1,600) (1,600)At December 31, 201779,422 8,884 209 2,781 1,758 93,054 Arising during the year 7- - - 1,126 1,133Write-backofunusedprovisions - - - - - -Discountrateadjustment&imputedinterest (31,251) (2,959) (107) 48 - (34,269)Unwinding of discount6,658744 17167 - 7,586Utilisation - - - - (66) (66)At December 31, 201854,836 6,669 119 2,996 2,818 67,438 Comprising:CurrentatDecember31,2017 - - - - - -Non-currentatDecember31,2017 79,422 8,884 209 2,781 1,758 93,054 79,422 8,884 209 2,781 1,758 93,054 Comprising:CurrentatDecember31,2018 - - - - - -Non-currentatDecember31,2018 54,836 6,669 119 2,996 2,818 67,438 54,836 6,669 119 2,996 2,818 67,438 depend upon future market prices for theEnvironmental risk provisionnecessarydecommissioningworksrequiredthatwillreflectmarketconditionsattherelevanttime. GOw2purchasedChevronin2011whichincludedFurthermore,thetimingofdecommissioning their marketing activities in Suriname of 22 petrol islikelytodependonwhenthefieldsceaseto stationsand3oilterminals.Thesesiteswillbeproduceateconomicallyviablerates.This,inturn, remediatedinanine-yeartimeframe.Thepresentwilldependuponfutureoilandgasprices,which value of the estimated costs as at December are inherently uncertain. 31,2018isUS$2,996(December31,2017isUS$2,781).TheamountrecognizedistheThediscountrateusedinthecalculationofthe best estimate calculated by management of the provisionasatDecember31,2018is10.28% expenditurerequired.(2017:8.38%).Other provisionsAprovisionatfairvalueofUS$2,818asatDecember31,2018(US$1,758asofDecember31,2017)mainlycompriseprovisionsforlitigationorcontractualclaims.Theclaimsaresubjecttolegalarbitrationandarenotexpectedtofinalizeduring2019.81'