2/11-10 S

General

The Hod Pod Prospect on the northeast flank of East Hod Field was first identified in 1991 as an anomaly on the existing 2D data. Additional work and mapping defined the prospect as a stratigraphic trap in the upper chalk that appeared to be separate from the main Tor reservoir of East Hod Field. The final well objective was defined by 3D seismic data completed in April 1993 as two stacked (upper and lower) pods in the uppermost part of the chalk. They were believed to be allochthonous chalk in an upper pod (Ekofisk Formation) and a lower pod (uppermost Tor Formation).

Operations and results

Wildcat well 2/11-10 S was drilled deviated from the centre slot (slot #4) of the Hod Platform with the Maersk Giant jack-up rig. It was spudded 28 February 1994 and drilled to TD at 4090 m (2920 m TVD RKB) in the Late Cretaceous Hod Formation. Severe problems with running the 13 3/8" casing were encountered, caused by mismatch in make between casing running tool and the casing thread. When pulling out casing centralisers and stop rings were left in the hole. The junk could not be fished and the well was sidetracked (2/11-10 S T2) from between 1397 m and 1547 m. The well was drilled with seawater down to 382 m, and with Novadril oil based mud from 382 m to TD.

Some oil shows were noted on claystone of the Hordaland Group from 1725 m and down to 1960 m. Top of the chalk, Ekofisk Formation, came in at 3900.5 m (2820.7 m TVD RKB), and oil was present. The high porosities predicted from seismic prior to drilling were present in both the Tor and Ekofisk Formations. The Ekofisk, however, had narrower pore throats than the Tor resulting in lower permeability. Oil staining was present in the cored upper Tor reservoir from 3913 m down to 3957 m. An oil column height of around 28 m (above the 95% Sw entry point) was calculated from special core analysis. The Tor Formation cored below 3957 m had lower porosity and permeability than the oil s