Aerated Fluids for Drilling of Geothermal Wells

Abstract

The utilisation of aerated fluids for drilling geothermal wells allows for full circulation of drilling fluids and drilling cuttings back to the surface while drilling through permeable formations, thus significantly reducing the risk of the drill string becoming stuck, of formation and wellbore skin damage, and for full geological control. The technique, an adaptation of straight air drilling and foam drilling techniques utilised by the oil and geothermal drilling industries, was initially developed by a team from Geothermal Energy New Zealand Ltd. during the late 1970?s and early 1980?s. Since the initial development, the technique has been successfully utilised in many geothermal drilling programmes worldwide. Most recently, the technique was introduced into Iceland?s geothermal drilling operations with remarkably successful results. To date 12 wells in three separate fields, Trolladygja, Hellisheidi, and Reykjanes have been completed successfully utilising aerated fluids. This paper is an update of a similar paper presented at the United Nations University Geothermal Training Programme, Visiting Lecturer?s, Presentations, September 2006.