Experimental study of effective cuttings transport in drilling highly inclined geothermal wells

Abstract

Japan is estimated to have the third-largest amount of geothermal resources in the world. However, developments have been restricted for several decades because approximately 80％ of the countryʼs geothermal resources are located in its national parks. Recently, the government has announced plans to approve the development of geothermal energy if access is made outside the national parks using directional drilling technology. The author experimentally studied effective cuttings transport for highly inclined geothermal wells in which drilling fluids with low to moderate viscosity and low density are generally used for the inhibition of drilling fluid gelation due to high temperature, the prevention of lost circulation, and the reduction of cost. Optimum drilling fluid properties and operating conditions determined on the basis of the experimental results were discussed in this study.