Development of Improved Rotary Seals for Downhole Motors in Geothermal Applications

Abstract

The major limitation of downhole mud motors for geothermal well drilling as well as straighthole oil and gas well drilling is the bearing section. Reduced bearing life has been a direct result of the inability to seal lubricant in a bearing section. Along with extending bearing life, a reliable rotary seal is needed to allow high pressure drops across the drill bit of improved bottomhole cleaning and increased drilling rate. A new approach to the development of an improved rotary seal is being carried out. The performance of candidate "high temperature" rotary seals compared with "standard" industry seal sis being measured in a full scale laboratory seal tester capable of simulating the temperatures, pressures and dynamic condition of geothermal well drilling. A description of the candidate "high temperature" seals, the seal tester and current seal results and findings are presented.