7119/12-2

General

Well 7119/12-2 is located in the Troms I area in the southwestern part of the Hammmerfest Basin. It was designed to test possible hydrocarbon accumulations in a seismic closure (Zeta-structure) in the southeastern part of the block. The primary objective of the well was sandstones of Middle Jurassic age. Secondary objectives were clastics of lower Jurassic and Upper Triassic age.

Operations and results

Wildcat well 7119/12-2 was spudded with the semi-submersible installation Ross Rig on 16 April 1981 and drilled to TD at 1902 m in the Late Triassic Fruholmen Formation. Boulder clays in the top 36" hole caused low rate of penetration and considerable difficulties in setting the 30" casing. Gas sands were encountered in the interval from 404-410 m. The 20" casing was set above this sands instead of the planned setting depth at 600 m. Due to high gas readings and increasing pore pressure, the drilling below 20" casing could not continue to planned 13 3/8" casing depth. Hence a 16" liner was set at 590 m. While underreaming below the liner, the underreamer failed to close and consequently could not be pulled to surface. The underreamer was left in the hole and the well sidetracked at 1215 m. The well was plugged back and the BOP-stack pulled when gas bubbles were observed coming out of the wellhead. To cure this problem the BOP-stack was installed again and previously set cement plugs drilled out to 275 m. A packer was set inside the 20" casing at 273 m and no more gas was seen coming from the well head. The well was then plugged back and abandoned. The well was drilled with spud mud down to 394 m and with gel/lignosulphonate/seawater from 394 m to TD.

Middle Jurassic to Late Triassic sandstones with good reservoir properties were encountered from 1372 m to TD. Drill cuttings and extensive coring had oil shows throughout, but RFT pressure gradients as well as logs and DST proved 100% water