A Directional Geothermal Well in Turkey: GK-4 Case Study

Abstract

Directional wells provide significant advantages in fracture permeability dominated systems, especially in the presence of parallel faulting dipping close to vertical. Directional wells also help overcome topographical limitations that constrain small geothermal fields. GK-4 well in the Gümü?köy Geothermal Project Area was planned as a directional re-injection well for up to 750 tons per hour of brine produced from the interim (1000- 1400m depths) and deeper (below 1900m depths) reservoirs. A TWD of 2600m was planned, with the target of injecting upstream into the recharge zone at the western boundary of the reservoir. The well was drilled successfully and completed at 1934m MD (1844m TWD) with total loss, albeit facing a high number of problems ranging from well pad size limitations, mud losses, faulting-related unwanted deviations, a temporarily stuck drillpipe and ultimately a compromised well completion configuration owing to an unstable zone at 1200m depth.