Bit of geology for you........Royston-1
Couple of posts made by 'Druid' today on the L-SE site are well worth a read:
'Time for a sermon RE Offset wells and porosity...and the implications for Royston. I'll try to make it as plain as possible, but will be both too simple and too complex.
These Herrera sediments have their provenance in the W/SW predominantly, which means the basin 'youngs' eastward and is more 'distal' eastward (distal=further from provenance or source of sediments)
More distal means more finer grained, more distal means less sand input,....NOT USUALLY GOOD!
For example, as discussed below, Carapal Ridge/Baraka/Baraka East/Catshill to the west are more proximal (i.e. less distal) to the sediment source, and so you'd expect BETTER petrophysics at CR1 et al.. (Not exactly though, because axially deposited turbidites like these, tend to have better poro-perms in the axial trend, than on the margins of the fairway when equidistant from the source....but nevertheless this is a fair general approx.)
So, this means that NO proximal well, i.e. well to the west, can really help deduce likely well performance at Royston...as we would expect them to be better (again, as long as not on basin margins i.e. too far south in this case).
What we need for comfort, is a well the EAST of Royston, so MORE distal....i,e, a well that should be poorer petrophysically than Royston...
And by Jove, we have one!!
This well is both in a more distal location, in a completely different structural setting (as it pinches out stratigraphically on the LS high which is the southern margin of the Miocene turbidite fairway), and..... it WAS TESTED!!
It looked like water on the logs, and it FLOWED A PILE of water from the same stratigraphy.
If it flowed water from the ratty crappy sands as it did at c.500bwpd, then if that same reservoir was filled with gas condensate...it would produce like the clappers!
So there we have a more distal, ratty stringy, low N:G sand reservoir, that performed VERY WELL !!! Halleluiah!!
NOW....
Royston appears to be both on the axis of Ortoire Syncline and more proximal than this well, and so it should have better sand development, better reservoir properties, and if charged with HC, should FLOW LIKE MAD!!
BTW.... that more distal and marginal Herrera well well is GY 614.
...and while we are talking wells, to further wet your whistles....I note that the ubiquitous Karamat sand is also charged.....I refer all to well CO-1, in the same sand to the west, in the same structural position as the Royston footwall....Hard to follow this sand, but with better data and more exploration....it is prolific.
It is rare in this environment to find a structure which is charged with HC in both hanging wall and footwall location, and also in multiple stratigraphic levels (LC, KMT, Herrera....and ???) !! What a kitchen!! TXP have discovered a gem of a structure, which is HC charged in it's most down plunge position, and leaves an entire trend up-plunge NE for the best blue sky exploration!'
'I think XM would scold me for not taking into account possible effects of any local diagenesis, as hydrothermal fluids move through the system depositing (usually carbonate or siliceous) cement like calcite or quartz overgrowths resp ....this can result in highly indurated sediments which can have a huge impact on reservoir quality.
However, I believe he'd forgive me on this occasion, because this is a relatively simple structure, and has therefore endured relatively few phases of tectonism's flushing pore-throat murdering interstitial mineralogy all over the place :-) as it does in the more complex Herrera structures to the north.......and they are oftentimes A OK across the length on the basin.
I like this structure, with it's up-plunge NE wide open acreage in the OB, and it's possible en echelon structures to the E....and now it seems charged with HC in the down plunge region! It's almost a fairy tale in a mature basin actually...
The other blocks in the east are suddenly way more attractive!!! Think about it...'