Denmark
During the autumn of 2006, the exploration well Karlebo-1 on licence 1/02 in Karlebo onshore Denmark was drilled. The well was Tethys Oil's first as operator. No significant amounts of hydrocarbons were detected in Karlebo-1, but the well was a milestone in Tethys' short history. Visit the image gallery and follow the drilling of Karlebo-1 in pictures.
The Danish licenses have now been relinquished.
Denmark is Europe's third largest producer of oil and natural gas with all production coming from off shore in the North Sea . Onshore Denmark and in particular Zealand is comparatively under-explored. Before Tethys drilling of Karlebo-1, only two exploration wells has been drilled on Zealand , both relatively long ago.
Geological results from the Karlebo-1 well
The Karlebo-1 well was drilled to a total depth of 2,489 m . in order to encounter Mesozoic aged sandstone reservoirs in a position that could have trapped oil or gas generated from deeper Paleozoic source rocks. The well penetrated a total of 300 m . of net reservoir sands in the pre-Chalk section, but failed to encounter hydrocarbons, and was plugged and abandoned as a dry hole.
Using data gathered from the Karlebo well the company has conducted a post-drilling appraisal of Licences 1/02. Additionally regional data and studies were analyzed for the Licence 1/03 area. In brief, the results are negative for continued exploration in these licences.
The analysis focuses on the source rock since the other necessary elements were found with the Karlebo borehole. All relevant literature and data regarding the Alum Shale has been gathered and reviewed. This leads to the conclusion that the Alum shale is a widespread excellent source rock and had an initial enormous hydrocarbon generating potential. Computer modelling of the thermal history of northeastern Denmark through geologic time was conducted with an industry standard software available for this purpose. Different scenarios of depositional history and temperature development were modelled and the results compared to other rock maturity data. In the best fit scenario the Alum shale became mature for oil during the middle Paleozoic, mature for gas in the late Palezoic time era.
Consequently the Alum shale probably generated most of its hydrocarbons before the Mesozoic reservoirs were deposited. Hydrocarbons may have been trapped during the pre-Permian phase; it is, however, quite unlikely that such accumulations would have survived the intense late Paleozoic tectonics intact. These results are expected to apply to a relatively large area around the southern part of Kattegat, Northern Zealand and also Djursland. Therefore, the company now sees very limited hydrocarbon potential in these areas.
Exploration drilling of Karlebo-1 (55°55'12.897” N; 12°25'04.042” E)
In the beginning of 2006, the preparations for the upcoming drilling were tangible. A drill site was contracted and in January 2006 a contract for the construction of the drilling site was signed. Already casing had been received and tendering for other longlead items was in progress.
During the spring, the constructive dialogue with the Karlebo authorities continued. On April 19, one of many public meetings was held, where local citizens and other interested parties could meet the management of Tethys and ask questions about the upcoming drilling.
In June, Tethys Oil AB received municipal approval to construct the well site. The construction of the some 5,000 square metres well site commenced in the second half of June and was finished in August. A total of 100 trucks carrying a total of 3,200 cubic metres of gravel and 50 trucks carrying 600 cubic metres of asphalt were required to be moved onto the location to construct the drill site, which included a complete closed drainage system to handle rain water. The drilling pad was reinforced with sixtyseven 10 meter piles and was designed to handle a drilling load of over 615,000 kilograms . In June, Tethys also entered into a drilling contract with the Polish company Oil and Gas Exploration Company Cracow Ltd. for the drilling of the Karelbo-1.
In July, Tethys Oil signed a Letter of Intent with Star Energy Group plc for Star Energy to become a 20% partner in Tethys Danish licences. Through the farmout, Tethys interest in the licences was reduced from 70% to 50%. The farmout arrangement called for Star Energy to pay 20% of historical costs and 40% of the cost of an exploration well on licence 1/02. Other partners are DONG E&P and Odin Energi A/S.
In September, the drilling rig mobilization commenced when the first out of 45 drilling rig loads arrived to the drilling site in Karlebo. In the end of September, the drilling operations commenced with an American IRI-750 rig. The operations were officially inaugurated on 27 September by Karlebo Mayor Olav Aaen. Some 100 invited guests were also present at the official opening.
On 18 October the well had been drilled to about 1,700 meters . The well was secured by casing that was set and cemented in place. On 14 November the well had reached a depth of 2,489 metres after having encountered problems at 1,916 metres , forcing a sidetrack to be drilled below the 7”casing shoe.
By 17 November it was clear that no significant amounts of hydrocarbons had been discovered and subsequently the well was plugged and abandoned.
Update Q2, 2007
With Tethys Oil as Operator, the exploration well Karlebo-1 on Licence 1/02 onshore Zealand was drilled at the end of last year. All necessary elements were found with the Karlebo borehole except for the source rock and the well failed to encounter hydrocarbons. Karlebo-1 was plugged and abandoned as a dry hole.
The company has conducted a post-drilling appraisal of Licences 1/02 and 1/03. In brief, the results are negative for continued exploration in these licences and the Danish licenses have been relinquished
Copyright 2004 Tethys Oil | Tethys Oil AB | Hovslagargatan 5 B, 1 tr. | SE-111 48 STOCKHOLM | Sweden