Uchenna Izundu
International Editor
LONDON, Nov. 9 -- Serica Energy PLC plans to proceed with commercial development of Columbus gas condensate field in the UK Central North Sea following results of two appraisal wells, one of which found a new reservoir with 40 ft pay.
Neither well was flow tested, as Serica said it collected enough information from drilling, coring, well logging, and fluid sampling.
The company drilled vertical appraisal well 23/16f-12 to a TD of 10,502 ft and hit gas and condensate-bearing Paleocene sands at a higher elevation than those tested in well 23/16f-11. Serica collected reservoir samples for analysis from the hydrocarbon-bearing interval.
"Reservoir pressure measurements indicate that this reservoir is separate [from] that discovered in well 23/16f‑11, and the full extent of this new accumulation is not yet known," Serica said, adding that the net pay in this new reservoir is about 40 vertical ft. The well is 3 km north of the Columbus discovery well.
Well 23/16f-12 had a gross gas column of 60 ft, and the sands were reached at a depth of 9,665 ft subsea—about 70 ft higher than at the Columbus discovery well.
The sidetrack well, drilled to a TD of 11,880 ft, also encountered gas and condensate-bearing Paleocene sands similar to those found in 23/16f-11. This was 9,802 ft subsea, about 70 ft deeper than at the discovery well. Net pay sand in the sidetrack well was about [70] vertical ft, compared with 56 vertical ft in 23/16f-11. It was drilled to a bottom-hole location 2.2 km north of the Columbus discovery well.
"Evaluation of downhole pressure data indicates that the sands encountered in the sidetrack are in pressure communication with those in the discovery well," Serica said. It has taken reservoir fluid samples for evaluation and will suspend the upper section of sidetrack well 23/16f-12z for future development of Columbus.
Serica Chief Executive Paul Ellis said: "The fact that hydrocarbons have been found over 3 km from the discovery well has opened up a second reservoir target in the field, the extent of which is as yet unknown. The sidetrack has found a thicker and potentially more-productive Columbus reservoir than that encountered in the discovery well, which is very encouraging for the prospects of development of Columbus and for further exploration in the area."
Serica plans to produce gas condensate from Columbus via a subsea tieback to adjacent Lomond field, which is operated by BP PLC. Field development studies are under way, and Serica will investigate other alternative export routes.
The interests held in Block 23/16f are operator Serica 50%, Endeavour Energy UK Ltd. 25%, and EOG Resources UK Ltd. 25%.
Contact Uchenna Izundu at [email protected].
