Wildcat well 35/2-1 is located on the Tampen Spur about one block west of the Agat discovery in the northern North Sea. The well should test the Peon prospect, a Pleistocene glaciofluvial / glaciomarine sand body. The very shallow prospect was based on a regional angular unconformity, an important boundary formed by glacier ice, separating steeply dipping Pliocene strata from sub-horizontal strata of Pleistocene age. The primary objectives were to test the presence and type of hydrocarbons in the prospect. The location was chosen close to the apex of a mound structure in the prospect, in an area where there was good HC indication and leaving acceptable up-dip volumes.
Operations and results
Well 35/2-1 was spudded with the semi-submersible installation Deepsea Trym on 21 July 2005 and drilled to TD at 713 m in Pleistocene sediments of the Nordland Group. The well was first spudded to the North of the final position and a 9 7/8" Pilot hole was drilled to 544 m. During drilling of the 36? hole opening the BHA parted in a drill collar connection. The BHA was left in the hole. The rig was moved 20m to the south and re-spudded. The well was drilled in a total of 39.7 days which was 5.8 days behind the AFE (33.9 days). The down time was mainly caused by operational and equipment failures including problems to get a pressure test on the P&A top cement plug. The well was drilled with water based mud.
Top Peon formation was found at 574 m. An 18.7 meter thick interval of dry gas was encountered in the 37.8 meter thick formation. The proven gas column was 18 m thinner than expected. The reservoir sand was homogeneous, but much unconsolidated, with likely permeability in the Darcy range. The petrophysical interpretation showed very good properties with an average porosity of 0.33, a net to gross of 0.99 and a water saturation of 0.12. The Gas Water Contact was estimated to be at 593 m (568m TVD MSL) from pressure evaluation and wire line logs. Residual gas was present in the water zone. Pressure data and PVT analysis showed that the reservoir is filled with an extremely dry gas containing 99.5 vol% methane. Analysis of stable carbon isotopes showed values around -72 to -73 ppt relative to PDB, showing a dominating biogenic origin for the gas. The reservoir pressure was 59.6 bar at 574 m (549 m TVD MSL). MDT sampling gave a temperature of 14.3 deg C at 589 m.
No cores were cut in the well and side wall coring failed. MDT fluid samples (gas) were collected at 587 and 593 m.
The well was suspended on 28 August 2005 as a gas discovery. The well would be re-entered for testing.
No drill stem test was performed.