Transition Zone Geosteering

With many major oilfields moving into decline, the importance of placing wells correctly relative to fluid contacts is becoming increasingly important. This paper discusses some aspects and highlights specific challenges of geosteering horizontal wells within or close to the oil-water transition zone using deep-reading resistivity measurements while drilling. Possible solutions are illustrated by examples from the Norwegian offshore oil fields Troll and Grane, showing the feasibility of geosteering along the OWC in long horizontal sections using advanced resistivity suites. Fit-for purpose solutions include extra deep reading resistivity and azimuthal resistivity while drilling, combined with predicitve resistivity response modelling.