25/11-20

General

Well 25/11-20 is located East of the Southern segment of the Grane field. The primary objectives of well 25/11-20 were to prove oil resources within reach of the Grane field production unit that can be produced through the Grane field installation and to test the geological and geophysical models for non-mounded Paleocene sands within the Licence area. The secondary objectives of well 25/11-20 were to define areas in the licence which can be relinquished and to reduce the uncertainties associated with the surrounding prospects. The well location was selected to provide an accurate seismic tie, i.e. an area with minimal compaction effects and away from faults, in an area where there are indications of a thick sand on the seismic data.

Operations and results

Well 25/11-20 was spudded with the semi-submersible installation "Treasure Saga" on 8 October1995 and drilled to TD at 1828 m in limestones of the Late Cretaceous Tor Formation. The well was drilled water based with seawater and hi-vis bentonite sweeps down to 1254 m and with KCl / Polymer from 1254 m to TD. Unpredicted boulders were encountered at 152 m to 157 m, causing low ROP and extra work to keep the inclination small, otherwise no significant problems were encountered during drilling. Shallow gas was not predicted and not observed

No sands or shows were encountered in the Rogaland Group. An internal high acoustic impedance shale was present at depth 1683 m to 1705 m where Heimdal sands were prognosed. The seismic response for this shale in the SOF data set was similar to the response for the Heimdal sand in the Grane Field. Four cores were cut between 1661 m and 1719.5 m in the Balder, Sele, Lista, and Våle Formations. Coring was stopped 20 m under the prognosed top of the main sand. The well was permanently abandoned on 23 October 1995 as a dry hole.

Testing

No drill stem test was performed.