Geothermal Drilling Fluids

Abstract

The elevated temperatures and unique geology of geothermal resources require special drilling fluid design considerations. Improperly designed drilling fluids can result in numerous drilling problems. Many products will degrade when exposed to bottom hole temperatures encountered in Geothermal drilling. This can result in increased product consumption, unstable drilling fluid properties, and wellbore instability. The thermal flocculation of solids can also lead to drilling problems. This can occur even when using thermally stable drilling fluid products. Clay flocculation increases viscosity an fluid loss. High temperature gelation and cementation can also result from poorly designed systems. The high temperature and acid gases encountered cause corrosion to occur at a greater rate. The increased rate of corrosion will reduce the drill string life and increase problems from drill string failure. Temperature stability by limiting active solids, by designing the drilling fluid system using thermally stable products, and the use of high temperature stabilizing additives.