Ann: Hydrocarbon gas recovered & evaluation program forward plan, page-1048

It was the well plan. In fact they pulled up way short of planned TD.

For starters Pilko they have gotten wireline down to TD, https://hotcopper.com.au/threads/ann-mukuyu-2-wireline-logging-progress-update.7682425/
The issue is clear as crystal to me, at least, below 3400m the pressure seems to go up exponentially and the porosity in the upper parts of the well can't deal with the mud weight required to prevent a kick.
They had control of the well down to 3400m which is why that depth has been chosen.
I suspect there is a decent margin of error in that depth also.
Just a reminder of what they have hit down to 3296m https://hotcopper.com.au/threads/ann-strong-gas-shows-in-multiple-upper-lower-angwa-reservoirs.7654651/

I'm of the opinion that Lower Angwa could be gigantic and oily.