Thanks Squidgy. That's rather reassuring. I haven't got a strat...

Thanks Squidgy. That's rather reassuring.

I haven't got a strat column to hand for this sequence, but was surprised that, from memory, we were being told that the overlying Jurassic markers were at the expected depth, and then suddenly that the top of Triassic target came in 19m low.

At the time, I checked the strat column in a past presentation and realised that there was an unconformity mapped between the two, so no problem there. The intervening unconformity is just stratigrpahically higher / a bit less eroded a this location.

But when they say that the reservoir '..overlies a regional shale basement' that also suggests to me that the reservoir SITS on an unconformity, over shale basement. If that is at the same stratigraphic level as it is in other wells, then the there would have to be part of the basal section of reservoir unit missing to accomodate it, with impermeable shale basement in its place.

I think I follow your point about the volumetrics though: if the whole package above and below the reservoir is part of the same structure, in terms of gross reservoir, the volume loss will simply be linearly proportional to the missing metres-drilled.

Of course, if as you say nothing is accurate to within 25m then this is all academic.

We wait.