1/3-7

General

Well 1/3-7 is located on the Hidra High in the North Sea. It was drilled to appraise the 1/3-6 Oselvar condensate discovery made in Paleocene Forties Formation sandstones. The well was placed down-flanks on the structure relative to the discovery well in order to penetrate the hydrocarbon-water contact and further appraise reservoir properties and production rates.

Operations and results

Appraisal well 1/3-7 was spudded with the 3 leg jack-up installation West Epsilon on 13 February 1995 and drilled to TD at 3345 m in the Paleocene Våle Formation. A gas kick was taken at 1740 m in the top of the Hordaland Group, later it was found that the gas probably originated from a limestone less than one meter thick. The hole packed off, the string had to be cut off at 1564 m, and the hole was plugged back. A technical sidetrack (1/3-7 T2) was made from 1204 m. This sidetrack failed as the bit fell back into the original hole during a wiper trip. A new and successful technical sidetrack (1/3-7 T3) was made from 1202 m. A second gas kick occurred in the T3 sidetrack when reaching 1741 m. This kick was controlled by the driller's method without significant problems or extra rig time. The extra activity caused by the first kick prolonged the rig time with 23 days. Due to poor hole conditions no open hole logging was performed in the 12 1/4" section. As the West Epsilon was available only up to 28 May open hole logging at final TD was also abandoned in order to secure time for the well test. The reservoir was logged through casing. The well was drilled with sea water down to 207 m and with gelled mud from 207 m to 1204 m. From 3103 m to TD it was drilled with a salt polymer.

Top Forties Formation was encountered at 3175 m. The Forties