So more to clarify my thinking on this Chilly.
The annmnt is clear in the JVs forward well development intent, this being:
* Shut-in for 6 weeks
* Imbibition
* Allow pressure build up
* Pressure observation/analysis
* Decision on continued natural flow or swabbing.
As we have all found out over the last few weeks this procedure is far from unique. But one still asks the question why should we need to do all this given the initial promise of the Ice 1 parameters.
My assertion would be that perhaps the JV has been a little too intent on seeing the positives with the reservoir and not remembering that rock mechs can come back to bite one on the posterior.
Over pressure can do impressive things but there are certain reservoir factors/forces that cannot be ignored.
Primary of these is the variable nature of the IN SITU actual shale micro structure and how it chemically reacts with the frac juice (FJ).
However we look at the permeability/porosity numbers this reservoir is still considered TIGHT in terms of the pore and pore throat (permeability) sizes. Yes we did get some impressive numbers in certain zones but certain zones do not make up the HRZ as a whole.
So the tightness of the HRZ will pretty much still behave as a shale normally would and in this regard we have typical capillary behavior.
I'm guessing the JV was hoping for, but did not get (at least at this location - which has always been a bit of a compromise), a scenario where the FJ would essentially flow back and flow back well given the % they expected. 30 % is very high for such a well type and given we have illite clays present possibly at 30-35% this may never have been a realistic target. (The other 60% or so being silaceous/quartzite mineraology)
Yes THOSE illites again.
Illites are known for their Hydrophyilic or water loving tendancy as r most clays. But the unique thing about Illite (and what PB no doubt saw) is that it is inherently
more stable or non-swelling that smectite clays.
Illites still have an intrinsic OUTER ionic structure which results in this water loving tendancy as water molecules LOVE to bind which such ions. Saada et al. (1995) explain the preferential
hydrophilic character of the illite by the presence of these cations at the surface of the grain.
http://www.clays.org/journal/archive/volume 45/45-2-184.pdf
The reason illte doesn't expand when binding with water is that there is a gap between each horizontal clay crystal that has poorly hydrated (wetted) potassium ions and these K+ ions bind the crystal layers together firmly whereas the smectite has poorly bonded crytal layers that easily allow binding with water molecules and then swelling occurs which is obviously damaging to a shale structure.
Now I'm assuming PB is no dummy when it comes to this stuff and as I say a primary reason for him to target the HRZ was his belief that there had been significant diagenetic transformation of the volcanic ash sourced smectite to the illite as it was being buried.
So its interesting that some form of assumption has been made that has resulted in over expectation of the FJ recovery %. Either that or the reservoir pressure or fluid physics is not coming up to spec, but lets not think about this ftm !
What is fact tho is that illite is strongly present and this may explain the lack of FJ recovery as the non-swelling but hydrophylic shale adsorbs the FJ.
Where one does need to be careful here is that illite will still tend to flake or separate on over saturation with water which does present the possibility of fracture blockage. However this should have been addressed with FJ additives.
So as long as there is enuf contact between the water molecules and the illite fraction of the shale we should get a decent volume of FJ water adsorbed, and given the likely fractured shale volume one could probably assume that there will be plenty of adsorption volume available.
Once the FJ water is adsorbed the water capillary force should dissipate and no longer be a dominant force and the formation over pressure should once again hold sway.
Its an interesting fact that some gas imbibition phases as long as a year have taken place in some shales and it has shown that these in fact result impressive increases in production so it seems the JV is of the belief that this imbibition phase needs a good chance to do its thing. Then again this time line may alter given how unknown the HRZ is in this respect.
http://www.csur.com/images/CSUR_events/2014/TL/Fastback_Slowback_Soakback-CSURApr2014_rvh.pdf
So assuming we get those pesky water molecules out of the way we come to the pressure situation.
Prawnstar mentioned the weight of the FJ column vs the hydrocarbons over-pressure-push, and one cannot under estimate the differential here imo. There is around an 20% density difference between high API hydrocarbons and water and this may be enuf at these kinds of depths and hydrostatic pressures (static weight of the well column fluid). This hydrocarbon density may well in fact be higher given the presence of vapor phase liquids.
But the point is that this may still be enuf to give issues with our well flow and we may therefore see the JV deeming it necessary to utilize the swabbing if the reservoir pressure cant initially do the job.
The point of this post is not to solve/explain the issues that Ice 2V may have but to try and explain why some of the complexities exist with this new type of shale.
The above is also not taking on board potential rock mech variations (permeability/porosity) that may exist within the HRZ strata, but then this is all a part of defining sweet spots and the best areas for recovering the potential resource.
We also have the GOR issue which can apparently only be nailed down by hydrocarbon sampling/testing.
As other posters have been patiently espousing as has the JV, to what appears to be a mounting new register, or do we just have an aweful lot of 88E peeps !, it takes time for the FJ to imbibe (which is what we all hope is happening).
Geology in general is not a fast working aspect of science and the timescales we see here in shales seem relatively slow but are incredibly fast when it comes to how long it has taken for these North Slope hydrocarbon reservoirs to establish.
Perhaps we should also note that as good as PB and his crew r they r not magicians and it will take all their knowledge and expertise to find the HRZ key, if possible and a part of this will be further analysis/exploration of this acreage.
At least they continue chasing the HRZ, even tho the shorter term money seems to have written them off !!!
d.
(20min delay)