Shallower oil water contact, low probability.14 Jun 2020 17:30
The H&P Advisory Ltd recent analysis of HUR :
https://t.co/8Z1RqVzboH?amp=1
– says, with regard to reviewing geological and reservoir models:
The company will take a more prudent approach, including the possibility of a shallower oil water contact, even though this is seen as low probability.
And, indeed, I find the results from the various vertical well tests compelling enough to consider that a possibly shallower OWC is indeed a low probability.
After all, for example, on the: “Lancaster oil down to of 1,620m TVDSS” written on the 7 Feb 2017 RNS re the 7Z well, it goes on to say that this was arrived at by:
“... the integration of wireline sample oil analysis, wireline logs, gas chromatography data, sidewall cores and the integration of Lancaster pressure and fluid data.”
Sounds like a lot of ‘belt and braces’ there supporting that "oil down to" depth. And we've had data from several vertical wells now, with similar deep "oil down to" numbers.
Looking at the chart of: “Testing the reservoir through stepped production increase” from the last Cap Mkt Day, I begin to feel that the 7z well could be getting water from more than one pocket of perched water.
One predominantly above the horizontal of the well and ‘pierced’ by the well – this one gives the initial spike of water when oil production is resumed after a shut in period – just as described in the Cap mkt day animation. This water pocket is emptying downwards into the 7Z, the water being replaced by oil coming into this ‘dead-end down’ pocket via fractures feeding into it from above.
But is there a second element here - a gentle rise in water cut over time is akin to conning behaviour, as is an increased proportion of water as flow rate is increased. But as the OWC is so much deeper than the wells, then the pressure drop that production is introducing form these high Productivity Index wells should only lift water, for example, some 55.6 metres for 15,000bopd being produced from 7Z - (based on a 7Z well PI of 190 stb/d/psi and water lifting 0.705metres per 1psi pressure drop ), and as the OWC / aquifer is some 265metres metres lower than the 7Z well, it looks to be a big safety margin. So, my thought is, we could have a second ‘dead-end down' pocket of trapped water sitting close below the 7Z well – close enough for that pocket to undergo, in effect, localized conning. So, not from the aquafer, but from another nearby water pocket. And that could be what we're seeing.
And, of course, as there is now a nicely cleaned up fissure connection between the heels of wells 6 and 7Z – when the 6 is producing on its own it can see the same water source(s) as the 7Z can - they’re just a bit further away than they are for the 7Z well, so water gets to the 6, but at a lower rate.
The FPSO's Produced water handling is shown as an impressive 20,000bpd, even so it would be really nice if the perched water pockets showed signs of emptying some time soon.
Just my thoughts, as always DYOR
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