25/2-9

General

Well 25/2-9 was designed to drill an assumed top in the eastern part of the Frigg East Beta structure, one of the Frigg Satellites, discovered by well 25/2-1 in 1973. The main objects of this well was to reveal petrophysical characteristics in an area where development wells could be located, to appraise the gas column height and gas in place, to get static formation pressure in order to estimate communication with the main Frigg field, and to obtain cores from the upper part of the Frigg Formation and the Balder formation for static and dynamic petrophysical measurements. Prognosed depth of the Frigg Formation was 1922 m, and planned TD was 2450 m.

Operations and results

Appraisal well 25/2-9 was spudded with Golar Nor Offshore A/S semi-submersibel rig Nortrym on 14 June 1985 and completed 24 July 1985 at a depth of 2297 m in the Paleocene Balder Formation. At 2297 m 800 l/min of mud was lost due to a leakage between 13 3/4" casing and 20" casing. The 9 5/8" casing was set to 888 m and the well was gradually brought under control. During this operation a part of the under-reamer was lost into the hole, and fishing went on for two days.

Top Frigg came in at 1935 m with hydrocarbons from 1935.9 m. Gas/oil contact was encountered at 1960 m, and an oil/water contact at 1972 m with brown oil stain on cuttings down to 2008 m. A total of 12 cores were cut with a total length of 214.25 m with 86% recovery. Ten cores were cut from 1939 m to 2145 m in the upper Frigg Formation, across the hydrocarbon bearing zone and all fluid contacts and two cores were cut from 2220 m to 2256 m in the tuffaceous Balder Formation. The cores consisted mainly of sands, more or less consolidated.

The well was plugged and abandoned as an oil and gas discovery.

Testing

No drill stem test was performed