RE: this is key, from the last RNS.9 Apr 2019 15:22
Ajax. The first drill went down 4,267m, and hit jurassic sands, deeper than expected, but water bearing. The sidetrack went up, to a depth of 3,811m, and hit oil in the higher sands.
The current drill has gone down 3,784m, without finding the jurassic sands at all. I think it's a safe assumption that that isn't because they just haven't gone deep enough. So they must have drilled into pre-Jurassic layers, and the geologists will know the sequence of layers. So, as the Jurassic layer is not continuous between this drill, and the last one, there must be a fault in between, which has interrupted the geological sequence.
But having said that, Equinor obviously expected to hit the Jurassic sands by drilling in this location, so I expect they are analysing the well logs and all other available data to try and figure out why they didn't. And they have much more data than me to go on.
It just seems to me, given my very simplistic reasoning, that as they have already sunk the cost of mobilising the rig for this drill, it would be relatively cheap to try and sidetrack back towards the original sweet spot.