Statoil ASA has gauged good oil rates on the west side of Johan Sverdrup field in the North Sea offshore Norway but said the latest appraisal wellbore also “reduces the possibility for upside potential in the basement section in the Johan Sverdrup area.”
The Statoil group on PL265 drilled the main 16/2-17S wellbore to appraise western Sverdrup and the 16/2-17B sidetrack to test potential in the Cliffhanger South area west of the field’s current outline.
The well’s purpose was to investigate reservoir thickness and properties close to the main bounding fault that marks the western limit of the Johan Sverdrup discovery.
The 16/2-17S wellbore found a gross 82-m oil column in Jurassic sandstones of which 39 m were of excellent quality. The well demonstrated exceptional flow properties in the upper part of the reservoir.
Partner Lundin Petroleum AB said the lower 43 m of oil column consists of interbedded shales and high-quality sandstone layers. An oil-water contact was established similar to neighboring wells. Both intervals were production-tested with rates of 5,900 b/d and 1,500 b/d, respectively. Both tests indicate large lateral reservoir extent, and the intervals are in pressure communication.
The 16/2-17B sidetrack, drilled 800 m west of the main wellbore, did not encounter Jurassic reservoir, and Cliffhanger South is therefore classified dry, Statoil said. Ciffhanger South was defined as a separate target in PL 265, and the outcome of the sidetrack does not have impact on volume estimates for Johan Sverdrup.
Gro G. Haatvedt, Statoil senior vice-president exploration Norway, said, “Statoil still sees potential in the Cliffhanger North area based on seismic data and our geological models, and will test it with a dedicated well later this summer.”
The 16/2-17B sidetrack also tested a secondary target in the granitic basement of the Utsira high (see map, OGJ, Apr. 4, 2011, p. 50). Core from this section contained oil shows but were confirmed to be nonproducible, Statoil said.
Johan Sverdrup field is in PL501, PL265, and PL502 on the Norwegian Continental Shelf. Statoil is operator of PL265 with 40% interest, Petoro AS has 30%, Det Norske Oljeselskap ASA 20%, and Lundin Norway AS 10%.