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Veslefrikk is a mature North Sea oil field where optimal well placement is critical for drainage of the remaining reserves. The two cases presented illustrate optimisation of horizontal wells in different geological settings. In both cases a newly developed directional resistivity logging while drilling tool was used to optimise the well location during drilling. The tool was able to detect resistivity contrasts in any direction up to 5 m from the wellbore. In the first well, the objective was to maximise the distance to the water and ensure that no oil was left above the well, by placing a horizontal section 1-3 m below the top of a lateral continuous reservoir sand. In the second case, the objective was to optimise the amount of oil filled sand along an 1100 m long horizontal section, while drilling perpendicular to the depositional direction of a fluvial channel system. The early detection of reservoir boundaries resulted in an increase of 10-15 % in the recoverable reserves for each well compared to conventional geosteering.