Progress on Drilling Fluid Technology for Hot Dry Rock Drilling

Abstract

Two key issues encountered in hot dry rock drilling are high temperature and lost circulation. This paper introduces the analyses made on the geological characteristics of hot dry rock and the drilling fluid technology required for drilling the hot dry rock, and surveying performed on drilling fluid system for hot dry rock drilling and the field applications of the drilling fluids. New technologies for hot dry rock drilling found both in China and abroad suitable for different formation conditions are summarized. Problems found of the hot dry rock drilling fluid are also presented with the prospecting for the development of the technology. Presently, polymer sulfonate water base drilling fluid is mainly used for hot dry rock drilling, however, some other drilling fluids, such as high temperature foam mud, aerated drilling fluid, liquefied nitrogen fluid etc. are also prospective fluids for hot dry rock drilling. These new hot dry rock drilling fluids have been successfully applied in field operation with good results; they impose low formation damage, and are high temperature and salt resistant. Other advantages include good adaptability to different formation conditions and performance in environment protection, all of which represent the future of the development of the hot dry drilling fluid technology.