Appraisal well extends Kraken success in UK North Sea
The Kraken appraisal well, 9/02b-4, on block 9/2b in the UK Central North Sea has been drilled to 4,502 ft MD, Nautical Petroleum announced today. The top of the target Heimdal III was encountered at 3,856 ft, with a gross thickness of 160 ft. The well proved a substantially thicker and higher porosity main Heimdal Unit III reservoir than expected.
Preliminary log evaluation indicates that the Heimdal III main sand contains 83 ft of net oil pay with an average porosity of 38.8% and an average oil saturation of 87.2%. No oil-water contact was encountered in the Heimdal III main sand; thus the Kraken Field oil-down-to (ODT) has been extended to a depth of 3,934 ft TVDss (1,199 m TVDss) from 3,842 ft TVDss (1,171 m TVDss) indicated in the 9/02b-2 well.
Upon completion of wireline logging, a 9 5/8-in. casing string was run and a 50-ft interval was perforated. A test string consisting of sand screens and an electric submersible pump was run, and the well was production tested. The testing programme was designed to recover uncontaminated reservoir fluid samples and to confirm the productivity of the reservoir tested in the discovery well, 9/02-1A. These objectives have been met, although operational problems caused by the exceptional quality of the reservoir encountered meant that it was not possible to flow the well at a stable production rate.
The well was initially pumped at a restricted rate of 300 bbl/day. A productivity index of 2 bpd/psi was indicated during this flow period, confirming the excellent multi-Darcy quality of the reservoir. Subsequent to this flow period, the productivity declined markedly. An injectivity test was completed, which showed an injectivity index of approximately 2 bpd/psi. This indicated that the productivity decline was due to the plugging of the sand screens rather than a reservoir or oil quality issue.
The well was thereafter produced at low rate to recover oil fluid samples, which will be used for development studies. Preliminary analysis indicates an in-situ oil viscosity of c.100 centipoise, similar to that seen in the 9/02b-2 well.
The lower section of the well will be abandoned, and the 9/02b-4z exploration sidetrack will be drilled to a target west of the 9/02b-4 well. The sidetrack is expected to take approximately 14 days.
Nautical’s joint venture partner Canamens North Sea Energy had previously announced that it would not participate in the 9/02b-4 well; therefore Nautical will hold 70% interest and Celtic Oil will hold 30% interest in that well. Additionally, Celtic Oil will not partake in the 9/02b-4z exploration sidetrack. As such, Nautical’s participation in this activity is 100%.
