RE: EPS Production24 Jul 2019 01:05
johnpwh,
"If the pressure is occurring naturally without the need to pump is it safe to let it flow at the maximum unassisted rate without fear of aquafer water appearing?"
Again, (and you're not the first one), you're bringing up the subject of that 'dreaded bogeyman', water ingress from the aquifer which is considered to be the 'pressure-drive' mechanism.
A possibility which the company has mitigated by drilling very high in the structure, hundreds of metres above the OWC (Oil-Water Contact).
Your question is valid, though, but in answer, no, there is no difference whether the current production is 'natural' or using the pumps. The natural flow reported far exceeds expectations, and I personally reckon there will be a lot more data-gathering before the ESP's are switched on for a 'ramp-up'.
Given that the two wells appear to be behaving almost like 'one borehole' (albeit draining 'only' about a 3.5km2 area!), that should be considered 'localised' when you look at the entire Lancaster area, and completely discounting possible extension up the ridge towards Halifax.
Plus (I think it's somewhere in Dr Trice's CMD presentation, though I'm too tired to watch it again right now), there was mention of 'horizontal connectivity' possibly being far greater than 'vertical'. Which is good news, both short and long-term. Because short-term we're dealing with 'shallow' wells, and longterm with more wells drilled, things can be 'balanced' even better.
Over the current limited (though rather large) drainage-area, there is the risk of creating a rather 'localised' pressure-drop zone which in a conventional reservoir might induce aquifer 'water-coning'. But the shut-in results (what little data one can squirrel out) appear to indicate the the Aquifer hasn't even noticed what's happening a few dozen storeys over its head!
(And I'm sorry if I seem to be slightly anthropomorphalising things, but when you're talking geology, the way oilwells work, and so on, it's not too weird. Mother Nature, Gaia Hypothesis, etc. etc.)
To answer your question. Yes, of course it's 'safe to go with max natural flow. Unless for some reason it isn't, but that would be a shame, because it would imply that installing the pumps was wasted expense!
Way back when, after 7z, we were told these wells could happily flow at 20,000 bbl/day with minimal'drawdown', and I believe that.
Just now wishing they'd bought a heftier boat, but maybe the 'market' wouldn't have gone for it. Just got that little bathtub-sized Aoka Mizu to do the job instead. Hey-ho!