1/3-8

General

Well 1/3-8 is located on the Hidra High in the North Sea. The primary objective was to test the Jurassic Upper Ula sand package within the Kamskjell prospect. The secondary objective was a sand package at the base of the Jurassic. Planned TD was tagging the Triassic or reaching 5085 meters TVD SS.

Operations and results

Wildcat well 1/3-8 was spudded with the 3 legs jack-up installation Transocean Nordic on 12 December 1996 and drilled to TD at 5199 m in the Triassic Smith Bank Formation. Two major unscheduled events occurred in the 12 1/4" section. First, the mud line hanger failed. A total of 16 days was required to repair this before drilling could be resumed. Secondly, and more serious, a 3.5 bbl kick was taken at 4529 m while drilling a limestone interval in the Early Cretaceous Cromer Knoll Group. Based on the worst case scenario interpretation of the kick, there could be a large volume of hydrocarbons (estimated at up to 300 bbls) in the annulus between the kick and thief zones. For this reason it was decided to rig up flare booms to increase the rig safety should it become necessary to by-pass the MGS whilst circulating out the influx. The well was opened up, and the influx circulated out at 3.3 bpm. Initially returns were taken through the MGS. After pumping 1464 bbls returns were switched from the MGS to the boom. This decision was taken as gas levels in the pit room were rising, and the seal leg pressure was dropping steadily (from 11.5 to 6.4 psi) indicating the onset of possible blow-down. The flare lit immediately with the clear burn characteristic of condensate. A total of 420 bbls was flared before mud was at surface and the flare extinguished. A total of 15 days were spent stabilising the well to permit running casing and continue drilling the next sect