It is difficult to adapt traditional screw motors with rubber stators to the high-temperature and high-pressure conditions in ultra-deep wells, where rubber stators age, deform and carbonize, resulting in motor failure. In this study, the goal is to develop volumetric power drilling tools that can be used to drill at depths of 10,000 m. To meet this goal, an all-metal screw motor that can be applied in ultra-deep wells is designed, then its deformation and structural design are studied. Through numerical simulation, the change in clearance of the motor after expansion in high-temperature environments and the characteristics of deformation in ultra-deep well environments are analyzed. The results show that the metal screw motor has good performance and stability. The maximum deformation is less than 0.3 mm at depths of 9000~15,000 m in ultra-deep wells. The minimum design clearance should be greater than 0.2 mm to ensure that the stator and rotor remain engaged. The results of this research are expected to provide theoretical guidance for the design of all-metal screw motors for applications in ultra-deep well drilling projects to meet the demand for deep earth resource development.

To establish in-situ fluidized coal mining technology and a theory of mining mechanics for deep coal resources, it is crucial to obtain a fidelity rock core that maintains deep in-situ conditions to understand the physical mechanics of deep rock. Doing so requires the development of in-situ condition-preserved coring (ICP-coring) technology. In this work, hollow glass microsphere/epoxy resin (HGM/EP) composite insulation materials with high strengths were prepared. An epoxy resin matrix with high strength and high-temperature resistance was selected from among epoxy resins cured by different curing agents. Then, a series of composite insulation materials with different HGM volume fractions were prepared. The mechanical strengths of the composites decreased with increasing HGM volume fraction. Then, thermal insulation materials suitable for different ICP-coring depths were selected. Changes in the thermal conductivities and mechanical strengths of the composites were characterized after they were subjected to high water pressure (45MPa). Verification of the applicability of the thermal insulation material under high water pressure (45MPa) conditions demonstrated that it met the working requirements for the ICP-coring device.