Redrilling of well EE-3 at the Los Alamos National Laboratory HDR (Hot Dry Rock) project

The successful sidetracking of well EE-3 and the drilling of well EE-3A proved that with detailed planning and by adjusting techniques based on previous experience at Fenton Hill, drilling can be accomplished with reduced risk. The primary drilling problems associated with drilling of hot, crystalline basement rock, are (a) abrasiveness between the downhole tools and the formations and (b) a crooked wellbore path. These were essentially eliminated by a specially designed drilling fluid and careful pre-planning of the directional drilling operations. These improvements have taken much of the risk out of drilling at the Fenton Hill Hot Dry Rock (HDR) Geothermal Test Site. The sidetracking of EE-3 and drilling of EE-3A were undertaken to complete the hydraulic connection between boreholes. Drilling through fractured regions indicated by the dense zones of microseismic activity increased the probability of success. EE-3 was sidetracked at 9373' and redrilled to a depth of 13,182'.