If the field is pumping say 100K boe per every day, which never...

If the field is pumping say 100K boe per every day, which never happens down time maintenance ect, it would take ~ 41 years to empty the reservoir/s based on 1.5 billion barrels of oil equivalent or the 100% of the field.
Yes the price you quote is the delivered price but 1 TCF net to IVZ would take ~ 15 years to pump out.

I personally think the game plan is to produce energy for Zimbabwe first and foremost, 2 x MOU is a hint, then off to the rest of Southern Africa.
I think Scott wants to truly turn Zimbabwe around and a discovery of this size would do that IMO.

Loooong way to go yet though.
The PSA done and dusted is first cab off the rank then hopefully closely followed by a farm out.
I do hope once they farm out they get their skates on.