Oil and gas group EnCore Oil (LON:EO.) said this morning that a new appraisal well on the Cladhan prospect in the UK Northern North Sea had confirmed both the presence of a large oil column in the main Cladhan reservoir as well as a new hydrocarbon bearing reservoir sequence. The well was drilled as part of an ongoing drilling programme that will assist in the planning of a field development conceptual design that is already underway for Cladhan. The EnCore Oil share price gained 6.5p to 125.5p yesterday in anticipation of the latest drilling news. In early trading today the shares fell slightly to 122p.

The Cladhan appraisal well 210/30a-4 was drilled as a deviated well to a total measured depth of 12,252 feet and encountered oil bearing Upper Jurassic sandstones in two separate reservoir intervals. No oil-water contact was observed. The Upper reservoir sequence had a gross true vertical thickness (TVT) of 18 feet and a net sand of 13 feet TVT. The sand has an average porosity of 16% and hydrocarbon saturation of 82%. EnCore said the pressures suggested that the reservoir was in a separate pressure regime from the Lower reservoir. In the Lower reservoir sequence, which until now has been the main reservoir in previous Cladhan wells, the well encountered a gross TVT of 256 feet and a net sand of 21 feet TVT. The sand has an average porosity of 16% and hydrocarbon saturation of 75%. Initial pressure data indicates that the lower sand is in pressure communication with, and is part of the original Cladhan discovery. The well has proven an Oil Down To of 10,447 feet True Vertical Depth Sub Sea (TVDSS), giving a minimum hydrocarbon column of over 1,200 feet.

The original Cladhan discovery was made in December 2008 but wasn’t drilled again until August last year when further appraisal uncovered a much larger discovery than anticipated. Two months earlier, the EnCore share price began to surge after it made a significant discovery at Catcher in the Central North Sea. The aim of the latest appraisal programme is to drill further down dip, looking for deeper oil in the structure to the east of previous wells drilled there. Sterling Resources, the block operator, has produced a resource estimate that puts P50 contingent resources at Cladhan at 89m barrels and prospective resources at 167m barrels. Sterling holds a…

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