Laboratory Measurement of Bit Bearing Temperatures in Rotary Drilling With the Garter Spring Pick-up System

In order to determine the factors affecting bearing temperatures—factors such as formation temperatures, rotary speed, bit thrust, airflow rate, and temperature—a pilot-scale laboratory micro-bit drill rig was instrumented. The paper describes the successful control of variables and measurements of bearing temperature of a thermocouple instrumented micro-bit using the garter spring pick-up system. The first step in tapping the energy of a geothermal reservoir, once it is located, is drilling the necessary wells to allow the heat energy to be transported to the surface. Currently, drilling for geothermal wells in elevated temperature formations is done using unsealed bits with air as the drilling fluid. Reduced bit life, due to bearing failure, with the consequent reduced overall penetration rates, can be attributed to the high temperature encountered. Limited knowledge and understanding of how temperature affects drilling operations is a deterrent to the improvement of the existing drilling system.