2/7-5

General

Well 2/7-5 was drilled ca 4.5 km north-northeast of the 2/7-4 well, which found oil in the Ekofisk and Tor Formations, the Edda Discovery. The objective of the 2/7-5 well was to test the Ekofisk and Tor Formations in order to appraise the extension of this discovery.

Operations and results

Appraisal well 2/7-5 was spudded with the semi-submersible installation Ocean Viking on 3 September 1972 and drilled to TD at 3353 m in the Late Cretaceous Tor Formation. The well was drilled water based with 3 - 6 % oil addition below 1217 m.

The Ekofisk Formation was encountered at 3110 m, and the Tor Formation at 3205 m. Both formations appeared to be hydrocarbon bearing, but the water saturation was high and the permeability was generally low, which probably explained the low flow rates of the zones tested.

Eight conventional cores were cut in the interval 3120 - 3158 m in the Ekofisk Formation, and another five cores were cut in the interval 3219 - 3300 m in the Tor Formation. The cores were reported to bleed gas and oil. Scattered shows (fluorescence) were observed from top of the cored interval and down to 3285 m in the deepest core (core 13). No wire line fluid samples were taken.

The well was permanently abandoned on 1 January 1973 as a dry well with shows.

Testing

Several drill stem tests were conducted in the limestone and chalk of the Ekofisk and Tor Formations. Many were unsuccessful. Of the technically successful tests DST 1 from 3274 m to 3293 m and DST 2 from 3225 - 3237 m flowed water. DST 3 from 3210 - 3219 m flowed water with gas and trace of oil. DST 4 from 3160 - 3185 m and DST 5 from 3120 - 3130 m flowed minor amounts of gas and water.