8/10-7 S

Well 8/10-7 S was drilled to test the Cassidy prospect on the Sørvestlandet High, about five kilometres north of the Oda field in the North Sea. The objective was to prove petroleum in the Late Jurassic Ula formation and to assess the reservoir properties in any other Jurassic and Triassic intervals in the Cassidy prospect.

Operations and results

Wildcat well 8/10-7 S was spudded with the jack-up installation Mærsk Interceptor on 4 December 2018 and drilled to TD at 3155 m (2973 m TVD) m in the Permian Zechstein Group. A 9 7/8" pilot hole was drilled from seabed to 800 m to evaluate the possibility of shallow gas. No gas was observed during drilling. However, when pulling out of hole after section TD, bubbles were detected in the water column by the ROV sonar and then confirmed visually with the ROV around the well. The gas was interpreted to be a hydrostatically pressured dissolved gas, swabbed in by a packed BHA inside a small annulus. Drilling operations proceeded without significant problems. The well was drilled with seawater with hi-vis pills Glydril displacement mud down to 800 m and with EMS-4600 oil-based mud from 800 m to TD.

The well encountered the Ula formation at 2938 m, 16 m thick and without any hydrocarbon indications. The overlying Farsund Formation was silty with traces of fine sand, while the Triassic intervals consisted of tight claystone. The well is dry. Oil shows were inconclusive due to the use of oil-based mud

No cores were cut. No pressure points or fluid samples were taken due to difficult bore hole conditions.

The well was permanently abandoned on 4 January 2019 as a dry well.

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