RE: CPR, Tech Review and Reserves Downgrade29 Aug 2020 11:11
@bransolbull,
I'm neither saying perched water or aquifer. But taking both into consideration as possible reasons for the watercut, when the toe of 7z is at 1280 m TVDSS (100m above the structural closure 1380 m TVDSS).
@Nic7760,
"If perched water it waas, should have emptied out a long time ago by now"
I don't think we can make this assumption. People are comparing the Lancaster FB to Vietnam, but this field (as per 2017 CPR) has closest analogues to Wangzhuang (China), West Puerto Chiquito (USA) and Zeit Bay (Egypt).
Personally, I'd agree that perched water in a large well reservoir should not produce the water cuts seen in 7z, especially for extended period of time. But this raises further questions.. how big is the perched water vs how big is the well reservoir?
Yes, there's data that shows that the well may be connected to more volume than expected, but read earlier post regarding bottom hole pressure, bubble point pressure and aquifer.
Now to the OWC - I don't think the CPR is wrong. THERE IS probably oil even below the 1380 m TVDSS structural closure. The CPR states this with confidence. But it seems like that in the current wells (6 and 7z), there's several scenarios:
1. This oil isn't commercially viable wih 6 or 7z (Note, the OWC for this field was obtained through the drill of well 7 and 7z is a sidetrack to the east). For example, the current fractures connected to 6 and 7z do not go beyond the structural closure.
2. The wells can produce the oil from beneath the 1380 m TVDSS structural closure, but due to limited connectivity of the fractures and the "hydrodynamic influences" experienced in FB, the rise in aquifer OWC is substanstial. I.e. it has already produced majority of the oil (that's accessible by 6 and 7z) via limited fracture connectivity from below 1380 m TVDSS, and so the aquifer for the 6 and 7z connectivity has caught up.
"My overall point remains, even with your numbers if they are true, that 7z pulls deeper than 6"
I don't think 7z can "pull deeper" than 6. If this is really aquifer water, then OWC has risen from 1380 m TVDSS (or even below that at 1653 m TVDSS) to around 1250 - 1300 m TVDSS since the start of the EPS - through the extraction of oil (and thus decrease in oil volume/pressure in the field).
What i'm trying to say is that 7z sidetrack will not be efficient or optimal solution to this.
As for HUR's material:
6 TVDSS is from slide 29 with speaker notes on the May 2015 presentation - "Devex - Enabling Geological Scale Dynamic Modelling of a Fractured Basement Reservoir using a high-Resolution Simulator - A UKCS Case Study -With speaker notes"
7z TVDSS is from Finding Petroleum's "Understanding Fractured Reservoirs & Rock" seminar, where Dr R Trice was a speaker. This isn't on HUR's website I don't think.
Slift.