2/11-9

General

Well 2/11-9 (South Hod Prospect) is located within production license PL033, which also contains the Hod Field and part of the Valhall field. The South Hod Prospect extends across the Norway/Denmark border. Well 2/11-9 was drilled to test the hydrocarbon potential of pre-Jurassic sandstones contained within a horst block bounded to the east by the major Skrubbe Fault. Lower Hod Chalk and postulated possible Late Jurassic sandstone comprised secondary objectives.

Operations and results

Well 2/11-9 was spudded with the 3 leg jack-up installation Maersk Gallant on 24 July 1993 and drilled to TD at 4406 m in Early Carboniferous sediments. The well was drilled in 139 days versus the planned 103 days. An incident involving the loss of a 2 Curie Cesium 137 source from the MWD tool at 3816 m in the 12 1/4" section and contamination of the drilling fluid system resulted in 51.7 days of unscheduled events during the course of the well. The final solution was to abandon the contaminated section and make a sidetrack from 3760 m. The well was drilled with seawater and bentonite pills down to 1008 m and with PHPA/KCl/glycol/polymer mud (ANCO 2000) from 1008 m to TD.

The prognosed Permian / Devonian sand units similar to Embla field, were not seen. Oil shows were observed in the Ekofisk, Tor and Hod Formations, typically associated with fractures, but the chalks were not of reservoir quality. The well penetrated a 612 m pre-Cretaceous section in which the Late Jurassic was absent. Top Carboniferous was set at 4055 m. Sandstone intervals were present, but there were no shows apart from an isolated show in a black claystone at 4119 m in the Carboniferous. Organic geochemical analyses of cuttings showed that the Carboniferous shales and coal beds were mainly Type III with a poor to fair potential for gas only. Four cores were cut, three from the interval 3038 m in the Våle Formation to 3070 m in the Ekofisk Chalk Formation and one in