Design and Experimental Study of Pressure Maintenance and Temperature Control System for Hydrate Pressure Core Processing Device

Processing and analyzing hydrate pressure cores in an in situ environment is of great significance for accurately assessing reservoir properties, safeguarding mining safety, and improving the efficiency of resource development. Aiming at the problem of decomposition due to temperature and pressure changes during the processing of hydrate cores, in this paper, a set of pressure maintenance and temperature control systems with active pressure and temperature regulation is designed to maintain the in situ environment of the cores. Through the establishment of a mathematical model of the system and the analysis of time‐domain dynamic characteristics, it is found that the pressure maintenance system has good stability and no steady‐state error, but there are problems of slow response speed and large overshooting; the temperature control system has fast response and small overshooting, but the steady‐state error is large. On the basis of the comparative analysis of proportional–integral–derivative (PID) control strategies, the optimization scheme of using proportional–derivative control for the pressure system and PID control for the temperature system is proposed. The experimental results show that the system can stably control the temperature in the device within the range of 3.0°C–4.5°C and the pressure fluctuation ≤ 3.8% during the core processing, which verifies the feasibility and validity of the designed system, and provides a reliable technical support for the hydrate pressure preservation core processing.