Mid. 5. They are not releasing results because they don't have to. Holding onto information is a form of power - political power as it relates to the Nigeria/STP region and competitive advantage over other businesses.
#5 - They are not releasing results because there is no decision on the optimum development path foreward (pipeline or floating platforms) and where it is politically beneficial to access or locate any required downstream infrastructure (Nigeria or STP).
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....and for what its worth, that is most compelling reason for the holdup as the finds are impressively large and intrinsically commercial.