Ann: Hydrocarbon gas recovered & evaluation program forward plan, page-1495

So my understanding is that the mud weight will be lower in the sidetrack compared to the final mud weight that resulted from the high pressure zones at the base of the Lower Angwa. But it’s not necessarily going to be lower than the original mud weight used when we first penetrated the top of the Upper Angwa.

Scott mentioned in the AGM that we had some losses as soon as we punched through the top seal layer for the UA at around 2200m with our original lower mud weight.

He also said that the water sample at 2197m was only able to be obtained because it was above the zone of differential sticking.

So this dictates that the zone of differential sticking is likely to be at the very top of the UA just below 2200m. Because if it was any deeper then they would have attempted a fluid sample in a potential zone of hydrocarbons in the UA above the zone of differential sticking, as well as the water sample at the very base of the Pebbly Arkose.

The implications for this is that if there is a large pressure differential in a short section of the well bore where we took losses which is causing the differential sticking, versus a small pressure differential over a longer section of the borehole through say a thick reservoir zone, then a lower mud weight is unlikely to prevent differential sticking happening again in the sidetrack.

We’re only talking about a difference in mud weight of 20% based on the formation pressures that have been mentioned.

And if you’re correct with the likely timescale on the CFA plot being 20sec ticks and 100sec major intervals, then they were only on station for 10min at 2934m before they almost got stuck. In my scenario above for the root cause of sticking, then I can’t see how a 20% lower mud weight would make much difference at all.

That’s why I’d love to know from Scott what his plan is. Stay and risk getting stuck, but be guaranteed of getting a sample. Or pull out straight away and sample on drill pipe which would have a much lower probability of success.