' s ▁up stream ▁oil ▁and ▁gas ▁companies : ▁Ab u ▁D hab i ▁Marine ▁Area ▁Oper ating ▁Company ▁( AD MA - OP CO ) ▁and ▁Zak um ▁Development ▁Company ▁( Z AD CO ). ▁With ▁re organisation , ▁and ▁the ▁exp iry ▁of ▁the ▁ 6 5 ▁year ▁old ▁AD MA ▁con cess ions , ▁the ▁off sh ore ▁con cess ions ▁are ▁now ▁split ▁by ▁fields . ▁AD NO C ▁ 6 0 % ▁then ▁the ▁ 4 0 % ▁is ▁split ▁into ▁Upper ▁Zak um ▁( Ex x on ▁/ ▁IN PE X ), ▁( min or ▁fields ▁U mm ▁Al ▁D alk , ▁S ata h ▁( In pe x ▁ 4 0 % )), ▁Lower ▁Zak um ▁( Total , ▁EN I , ▁ON GC , ▁IN PE X ), ▁U mm ▁Sh a if ▁and ▁Nas r ▁( Total , ▁EN I ), ▁Sar b ▁and ▁U mm ▁L ulu ▁( CE PS A ▁ 4 0 %). ▁ ▁AD NO C ▁Dr illing ▁The ▁AD NO C ▁Dr illing ▁is ▁the ▁AD NO C ' s ▁oldest ▁subs idi ary . ▁It ▁is ▁previously ▁known ▁as ▁National ▁Dr illing ▁Company , ▁N DC . ▁AD NO C ▁Dr illing ▁is ▁the ▁largest ▁dr illing ▁company ▁in ▁the ▁Middle ▁East . ▁It ▁dr ills ▁for ▁oil ▁both ▁on sh ore ▁and ▁off sh ore ▁in ▁Ab u ▁D hab i . ▁AD NO C ▁has ▁ 1 0 0 % ▁equ ity ▁in ▁the ▁AD NO