Research on technology scheme for high-temperature downhole-motor test

Abstract:

The complex operating conditions encountered in deep， ultra-deep， and high-temperature geothermal wells impose stringent requirements on the high-temperature adaptability， output stability， and service reliability of downhole motors. The test in the ground simulation environment becomes the key link before the drilling tool enters the well. However， facilities capable of dynamically testing downhole-motor at temperatures of up to 300 ℃ under high-pressure conditions remain unavailable， constituting a key technical challenge， which must be addressed in deep-earth drilling projects. In this study， surveys and comparative analysis are firstly made including the technical characteristics and major limitations of representative downhole-motor testing systems developed in China and abroad. To meet the requirements of scientific drilling in 10000 m-class ultra-deep wells， a preliminary testing scheme for high-temperature downhole-motor is then proposed. A closed-loop circulation system for high-temperature， high-pressure drilling fluid is established using multiple high-temperature screw pumps connected in series， whole-system thermal insulation， and centrally cooled distributed rotary seals. Drive-load regenerative energy feedback and condition monitoring are incorporated to reduce power consumption and support extended-duration testing. Simulated loading and actual rock-drilling modules are integrated to evaluate the operating characteristics of downhole-motor as well as their adaptability to drilling and coring processes. The proposed scheme provides a technical basis for the subsequent development of a high-temperature downhole-motor test platform.