Study on the Working Characteristics of Dynamic Seal of Volumetric Metal Blade Motor

Summary The scientific drilling of ultradeep wells faces problems such as high-temperature and high-pressure conditions, poor surface drive feasibility, and low reliability. Therefore, it is an inevitable choice to use all-metal bottomhole power drilling tools. The key component of the all-metal positive displacement power drilling tool is its dynamic sealing structure, which determines its dynamic characteristics. In this paper, we study the working process and output characteristics of the dynamic sealing structure of the radial dynamic sealing structure of a metal roller to provide a reference for the research and development of a new type of volumetric downhole motor. Based on the metal roller radial dynamic seal structure, we establish a theoretical model of the movement and force of the roller dynamic seal working process by using the basic theory of fluid mechanics. We further optimize the optimal structural parameters to ensure the efficient operation of the motor. In addition, we establish the leakage model of roller radial dynamic seal gap based on gap flow theory. Through numerical analysis and computational fluid simulation, we obtain the influence of dynamic seal gap leakage on gap height, pressure difference between high- and low-pressure chambers, viscosity coefficient, and rotational speed. We establish a mathematical model of the dynamic output characteristics of the motor dynamic seal: The average output torque of the designed all-metal volumetric power drilling tool is 1004.16 N·m, and the output mechanical efficiency is 78.45%, which lays a certain foundation for the popularization and application of the new all-metal volumetric downhole power drilling tool.