RE: Drill Stem Test19 Oct 2020 10:44
Rubey has posted a link to an interesting document which has been discussed on Reabold’s LSE board too. But please bear in mind what this document is: it’s the Environment Agency’s July 2016 consent to Rathlin’s 2015 application for the construction of the B well site. We are not looking at the detailed B-1 drilling programme here, and Rathlin’s understanding of the local geology will probably have have changed quite a bit in the intervening years, thanks in part to the WN A-2 well. Rathlin’s detailed B-1 DP is not available to us, but it's probably much more recent. In response to the suggestion that they might carry out a DST while still in the Kirkham Abbey, they are clearly allowed to do this in the EA’s document but, for safety reasons and with all the public scrutiny, they probably won't do this. This has mainly to do with the Zechstein pressure regime, with different / high pressures being possible in each of the KA & Cadeby reservoirs, and the pressure doesn't always increase gradually with depth. This means they will almost certainly want to get the Cadeby behind casing before they do any testing, regardless of where oil and / or gas are seen while drilling. IMO, of course. Also, it's unlikely to be a simple DST (drill stem test) because this implies an open hole test using packers. These are almost never carried out these days when drilling in the Zechstein. This is again to do with the pressure uncertainties. In addition, the well will probably reach its total depth at / in the top of the Carbonifereous, as in most wells in the area. This means they will also penetrate the Rotliegendes, which is a gas-bearing reservoir in the nearby Southern North Sea. This is likely to be normally pressured, but they will want this behind casing too. They certainly won't want to use another casing string if they can avoid it. Sorry for this rather long response.