25/1-5

General

Well 25/1-5 was drilled southeast flank of the main Frigg structure in the North Sea, about 2.25 km from the discovery well 25/1-1. The objectives were to provide data for development of the Frigg Field and calibrate the seismic model.

Operations and results

Appraisal well 25/1-5 was spudded with the semi-submersible installation Deepsea Driller on 24 July 1975 and drilled to TD at 2259 m in the Paleocene Balder Formation. The well was drilled with spud mud down to 464 m, with KCl mud from 464 to TD.

The Frigg sands were encountered at 1907 m. It was 275 m thick with 225 m net sandstone. The Frigg Formation was gas bearing down to the GOC at 1976 m, oil bearing down to an an oil/water transition zone down to 1982 m and the oil/water contact at 1987 m. The only shows described in the well were in the Frigg reservoir: "First significant gas increase in drilling was recorded at 1908 m. Sand on cores showed a gas bearing facies, i.e. dry outlook, faint direct yellow fluo but strong cut. Gas ground began to decrease below 1970 m, becoming nil after 2010 m. Strong direct fluo on cuttings and side wall cores was observed from 1970 m to 2010 m."

Two cores were cut in the Frigg Formation. Core 1 was cut from 1914 to 1923 m and core 2 was cut from 1928 to 1937 m. cores were cut. FIT fluid samples were taken at 1979.6 m (oil and filtrate), 1981 m (oil and filtrate), 1937 m (gas and filtrate), and 1945.5 m (gas and filtrate).

The well was permanently abandoned on 12 September 1975 as an oil and gas appraisal well.

Testing

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