34/12-1

General

The 34/12-1 Afrodite well was drilled in the northern Viking Graben in the North Sea. The Afrodite structure is a horst block of Jurassic age bounded by north-south trending faults. The main purpose was to test the Middle Jurassic Brent Group and Cook sandstone of the Dunlin Group for hydrocarbons. The primary target was the Brent Group sandstones with the Cook sandstone as the secondary target. The well was classified as high temperature/high pressure (HTHP).

Operations and results

Well 34/12-1 was spudded with the semi-submersible installation Transocean Leader on 30 April 2008 and drilled to TD at 4713 m in the Early Jurassic Cook Formation. A pilot hole was drilled prior to drilling the 26" hole to check for shallow gas. No shallow gas was encountered. The well was accidentally sidetracked at 1391m when drilling out a cement plug. The plug had been set as a barrier in the well to allow the BOP to be pulled for repair. The well was drilled with spud mud down to 1261 m, with Ultradril mud from 1261 m to 3210 m, and with Paratherm oil based mud from 3210 m to TD.

The primary target Brent Group was encountered at 4320.8 m. The Brent Group comprised 52 m of net pay gas condensate bearing sandstones of 13% average porosity. No HC water contact was found. The secondary target Cook sandstones encountered at 4740 m were water wet. High background gas and gas peaks were observed when drilling through the Brent Group. Shows on cuttings and side wall cores from the Brent Group and Cook Formation were very weak and indistinguishable from the cut due to oil based mud. The average permeability in the Brent Group reservoir was low with an average below 0.1 mD. The low permeability was mainly caused by the presence of illite.</spa