▁pressure ▁maintenance ▁was ▁an ▁issue . ▁F resh ▁water ▁was ▁used , ▁available ▁from ▁about ▁ 4 6 ▁m ▁to ▁ 5 1 8 ▁m . ▁Some ▁areas ▁used ▁down hole ▁p umps ▁to ▁maintain ▁production . ▁Des al ters ▁were ▁also ▁added , ▁since ▁the ▁large ▁salt ▁amounts ▁entra ined ▁in ▁cru de ▁production ▁were ▁un tol er able ▁by ▁many ▁ref iner ies . ▁ ▁Notes : ▁ 1 . ▁Cru de ▁oil ▁Am ount s ▁in ▁bill ions ▁of ▁bar rel s . ▁ ▁Disc overy ▁Method ▁Sar ir ▁was ▁discovered ▁by ▁ge oph ys ical ▁methods ▁and ▁sub sur face ▁ge ology ▁with ▁no ▁top ographic ▁or ▁ge omorphic ▁anom al ies ▁being ▁reported . ▁An ▁air ▁magnet ometer ▁revealed ▁the ▁south western ▁A ▁structure ▁and ▁its ▁sout he astern ▁prolong ation , ▁which ▁was ▁later ▁found ▁to ▁be ▁a ▁buried ▁fault ▁line . ▁Sar ir ▁is ▁located ▁on ▁the ▁north west ▁pl unge ▁of ▁a ▁gravity ▁maximum ▁axis ▁and ▁over shadow ed ▁by ▁two ▁western ▁features : ▁( 1 ) ▁a ▁large ▁gravity ▁maximum , ▁the ▁A ▁structure ; ▁( 2 ) ▁a ▁strong ▁gravity ▁maximum , ▁the ▁B ▁structure . ▁The ▁eastern ▁feature , ▁rising ▁to ▁a ▁gravity ▁maximum , ▁is ▁known ▁as ▁the ▁C ▁structure ▁( S ar ir ▁C ). ▁ ▁Se ism ic ▁reflection ▁and ▁ref raction ▁surve ys ▁( 1 9 6 0 - 1 9 6 1 ) ▁revealed ▁that ▁the ▁C ▁structure ▁has ▁a ▁pron ounced ▁bas ement ▁feature . ▁An