EnCore Oil says that the Cladhan appraisal well 210/30a-4z located in UK North Sea Block 210/30a has reached Total Measured Depth of 15,900 feet (12,312 feet Total Vertical Depth Sub Sea).

The appraisal well was drilled as a side-track to evaluate the Upper Jurassic sands, approximately 1,000 feet deeper than the 210/30a-4 well. The side-track encountered two separate reservoir intervals with a gross True Vertical Thickness of 12 feet and 169 feet. Although hydrocarbon shows were encountered in both reservoirs, the sandstones have an average porosity of less than 10% and it has not been possible to confirm if the sands are hydrocarbon bearing and in pressure communication with the original Cladhan discovery.

Upon completion of operations at well 210/30a-4z, the Transocean Prospect semi-submersible rig will commence a second side-track well, 210/30a-4y which will drill into the shallower, Central channel to the South. It is expected that this side-track will take approximately 25 to 30 days subject to weather or operational delays.

Commenting on the latest well result, Alan Booth, EnCore's Chief Executive Officer said, "The principal aim of this aggressive down-dip step out well, some 2,500 feet down-dip from the currently mapped crest of the structure, was to try and obtain three key pieces of information; the location of the oil water contact, either directly or indirectly; an understanding of the nature of any reservoir development in the down-dip 'fan' area of Cladhan; and to better understand if the low net to gross pay in the previous well was related to the specific depositional environment at that location, or if there was also some porosity reduction due to depth.

"I think we can now answer the second two points. There does appear to be an element of porosity degradation related to depth as well as the nature of the depositional environment. The fan area does appear to contain well developed reservoir sequences. However these would appear to have been affected by the depth of burial and at this location, do not constitute effective reservoir.

"The answer to the first point, the oil water contact, is more problematic as no pressure measurements or fluid samples could be obtained from the reservoir. However, oil shows were reported whilst drilling throughout the sequence which suggests there may be oil contained within the tight reservoir. If this is the case, it might suggest that the limit to producible hydrocarbons is potentially related to porosity reduction and that there is in effect no oil water contact. This is a situation that has previously been encountered in this part on the North Sea.

"We now expect to drill two more side-tracks from this well location, one to test the central channel to the south of, and up dip of, the previous well, and then a second side-track location somewhere close to the current rig location. Both these wells will add significantly to our understanding of hydrocarbon distribution in the Cladhan field".

The equity in the Cladhan joint venture partnership is as follows: EnCore Oil plc (16.6 per cent.), Sterling Resources Ltd (39.9 per cent., Operator), Wintershall (UK North Sea) Limited (33.5 per cent.) and Dyas (10 per cent.).

Tags: EnCore Oil plc