High-temperature geothermal well resource exploration faces high-temperature and high-pressure environments at the bottom of the hole. The all-metal turbodrill has the advantages of high-temperature resistance and corrosion resistance and has good application prospects. Multistage hydraulic components, consisting of stators and rotors, are the key to the turbodrill. The purpose of this paper is to provide a basis for designing turbodrill blades with high-density drilling fluid under high-temperature conditions. Based on the basic equation of pseudo-fluid two-phase flow and the modified Bernoulli equation, a mathematical model for the coupling of two-phase viscous fluid flow with the turbodrill blade is established. A single-stage blade performance prediction model is proposed and extended to multi-stage blades. A Computational Fluid Dynamics (CFD) model of a 100-stage turbodrill blade channel is established, and the multi-stage blade simulation results for different fluid properties are given. The analysis confirms the influence of fluid viscosity and fluid density on the output performance of the turbodrill. The research results show that compared with the condition of clear water, the high-viscosity and high-density conditions (viscosity 16 mPa∙s, density 1.4 g/cm3) will increase the braking torque of the turbodrill by 24.2%, the peak power by 19.8%, and the pressure drop by 52.1%. The results will be beneficial to the modification of the geometry model of the blade and guide the on-site application of the turbodrill to improve drilling efficiency.

The Zhangjiakou area is rich in geothermal resources, and many counties in the region have discovered low-temperature geothermal. Structurally, Huailai County, Zhangjiakou City is located at the intersection of Zhangjiakou-Penglai Fault Zone and Shanxi Fault Basin (or Fenwei Seismic Tectonic Zone), namely the Yanqing-Huailai Basin (Yanhuai Basin). A large amount of geothermal resource investigation and research works has preliminarily defined that the area has good geothermal resource accumulation conditions. From 2019 to 2020, the China Geological Survey has organized several investigation and research in the area for in-depth geothermal resource. As one method of the survey results verification, a parameter well for geothermal resource survey was deployed as ZK02 and completed at 3000m depth. The ZK02 well was completed at a depth of 3006.9m, drilling through the Quaternary, Neogene, and Jixian strata, and entered the Archean gneiss strata. The well successfully explored high-quality artesian heat storage in the Jixian strata, obtained deep geothermal geological data and physical data, revealed the regional stratigraphic sequence and geological structure characteristics, and provided a scientific basis for regional geothermal resource potential evaluation. Based on the engineering practice of ZK02 well, this paper systematically summarizes drilling technology and experience from well structure to drilling equipment, construction technology and key technology, analyses the complex conditions and countermeasures downhole, and provide reference for the follow-up regional geothermal resources investigation, research and development and.