Lundin and partners are steadily continuing an extensive 2021 nine-well drilling campaign and other activities in the Greater Edvard Grieg area. Amongst those were the near-Solveig well 16/4-13S to explore the Segment D prospect and the recently announced start of an extended well test on the Rolvsnes basement discovery.
Now, the operator has moved to the north of the greater Edvard Grieg area, where it spudded well 16/1-34S in PL167 early July. The S well appraised the Heimdal reservoir of the Verdandi discovery and also tested a Jurassic prospect named Garun, situated mainly to the east of Lille Prinsen. The subsequent A well, which is currently drilling, appraises the Zechstein reservoirs of the Lille Prinsen discovery itself.
Zechstein carbonates
The Lille Prinsen discovery is a bit of an anomaly in the sense that the reservoir consists of Zechstein carbonates. As shown during a Force seminar in 2019 by Israel Poloni from Lundin, Zechstein carbonates in this part of the Northern Permian Basin have been drilled more than 100 times, but have hardly ever been the primary target. One of the reasons for this is the known reservoir issue of dedolomitization, which has caused a complete loss of porosity.
The primary target for the Lille Prinsen discovery well 16/1-29S was not the Zechstein either; it was expected that Triassic and thin overlying Jurassic sands would be found. However, the well didn’t prove any of these Mesozoic reservoirs though, but went straight into a succession of Zechstein dolostones below the Upper Cretaceous Shetland Group. The Permian reservoir, which is characterised by an average porosity of 23%, hosts an oil column of 95 m with 27 m of gross reservoir and was estimated to hold between 16 and 35 MMboe recoverable.
A year later, the 16/1-30S and A wells were drilled to the west of Lille Prinsen to further appraise the Zechstein reservoir, but both wells drilled a Jurassic sandstone rather than carbonates, which added up to 6.3 MMb of recoverable oil.
The eastern margin
So, now it is the eastern part of the Zechstein reservoir that is being tested. Although the top hole is situated outside the discovery polygon, it is expected that the A well deviates into the perimeter of the field rather than testing another segment such as 16/1-30A. The S well has deviated towards the northeast and has probably tested the margin of the Paleocene Heimdal Verdandi accumulation before landing into expected Jurassic sandstones of the Garun prospect.
The outline of the Garun prospect is indicated in blue on the map above, and was derived from the Lundin investors presentation held in January this year. Although the prospect seems to lie mostly to the northeast of the Verdandi outline, a bit of its extent reaches towards the west where well 16/1-30 was drilled. Therefore, it seems as if the Garun prospect represents a sheet of Jurassic sandstones that is present mostly around the slightly more elevated Zechstein carbonates of Lille Prinsen. It is therefore interesting to see what the contact in the S well will be, if oil is found in the first place.
In that light, even though I started writing this piece thinking that the S well has more of an exploratory character, it may equally be seen as an appraisal of the Jurassic 16/1-30 find.
Let’s soon find out what the press release says.
HENK KOMBRINK
