RE: New question 're T3923 Jul 2018 23:29
Pecten, my read from the details that you posted there (I have taken them as read, not read the EDI info myself as yet) are that they wished to perforate a 21m section somewhere between 2970m to 3000m, and the likelihood for deepening to only 56m past that rather than go further is less likely to do with time and more to do with that was all that they needed.
I suspect that the additional 56m may have been to form a sump ( reasonably standard practice, especially when trying to mitigate additional cost0, so as to run tubing conveyed perforating guns, fire them, then drop them into the sump without the need to trip all the tubing it of the hole and back in again if all they are going to perform is a basic DST.
Were that to have been the case then they would have achieved early indication that they were in a productive zone so that they would not then be going to the expense of fraccing a zone with zero productivity latterly.
However, as can commonly be the case in old (i.e. not very well completed initially) wells the cement bond log appears to have been very poor, and when fracced there was insufficient isolation to make the produced flow take the intended route (i.e. through the perfs in the production liner and up the test string contained within the liner), and instead the formation was instead producing into the annulus between the outside of the liner and the formation (which would not have occurred in a properly cemented liner job, as the cement would have been filling that void).
Alternately, the formation around the liner may have broken down (not only was the formation perfed it was also fracced, and that by its nature is very invasive and destabilising of the near bore formation), and the break down of the formation collapsing into the annulus void between the liner and formation as no cement was there to prevent that, and in doing so it blocked off the perfs in the liner inhibiting the flow in through the perfs to the test string.
Yes, running a CBL in advance would have informed them that the cement bond was very poor and likely to fail, but given that the frac equipment and test string would already have been on site they most rightly thought “in for a penny, in for a pound”, and chose to try it anyway, as the incremental cost to do so given that the equipment was already on site was small potatoes in the grand scheme of things.
Above is IMHO, is purely conjecture, and far from me stating that this was indeed what happened, they are merely my musings you understand.
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