Ann: FAR Senegal Sale Announcement, page-215

Here is the tranacript from WPL 2019 investor day. Key phrase is 'phase one is going for the lower reservoir'.
So as I said the 400 sands wont be extracted in any great extent in phase 1.

Phase 2 would commence in roughly 2030.

Ben Wilson: (RBC, Analyst) Thanks for that. Just a quick one - thanks for the granularity on Sangomar phase one CapEx. As you look at phase two, the next 250 million odd barrels, what sort of confidence level do you have, at this point, around that scope for phase two? Or will that evolve as you see phase one production?
Peter Coleman: Look, it will get de-risked, clearly, as we go through phase one. That was really the intention of why we developed phase one the way we are. Remember, phase one is going for the lower reservoir. The upper reservoir has about 3 billion barrels in place, but the sands are not connected. We’ll drill anywhere between 24 to 27 wells penetrations through that upper reservoir as we develop the lower and of course, some of those wells will actually produce in that upper reservoir so we’ll get a lot more information on it. We’re also running probably the densest seismic survey that we’ve ever run for Woodside - the most technologically complex survey right now and we’ll have that data available to us as well. We just waned to make sure that we don’t over-capitalise in the field, but we’ll get more than 20 well penetrations into this reservoir. Half a dozen of those wells will actually flow the reservoir so we’ll be able to unlock it