I think Barney that IVZ will want to stay above 50%, as you have the numbers above, at least for a while yet.
I agree it looks good, assuming you are close to the mark, only caveat I would have is how many wells? I would want to see 3 at least, 2 shallow, East and Shelf Edge and another Mukuyu well.
I honestly don't know if IVZ are in a Joint Venture, and have a JV agreement, or whether its some kind of subsidiary deal with Geo Associates? They handed IVZ 400 shares which is 80% of SG4571 see below, but it appears there are a few holding companies involved so it may not be a JV in the sense of the word.
From the 2018 annual report.
