Development and Experimental Validation of Active In Situ Temperature-Preserved Coring Testing System for Deep Oil and Gas Reservoirs

Deep oil and gas reservoirs exist under high-temperature and high-pressure (HTHP) conditions. Conventional coring without thermal preservation during retrieval induces thermal imbalance, biasing petrophysical and phase measurements and distorting resource evaluation. Internationally, most temperature-preserved corers are designed for low-temperature conditions and rely on passive insulation, whereas existing HTHP simulators can reproduce pressure and temperature but lack the capability to evaluate active thermal retention throughout coring and retrieval. Here, we develop and validate a full-scale testing platform for active in situ temperature-preserved coring (active ITP-coring), consisting of a simulated HTHP core chamber, a through-chamber conductive module, a high-pressure simulation module, an ambient-temperature simulation module, and a data acquisition and control module. The system operates stably at 150 °C and 140 MPa, reproduces realistic ambient cooling histories (with maximum and average rates of 11.22 and 5.11 °C/min), and demonstrates that, under HTHP conditions, active preservation limits the internal temperature drop to 4.2 °C over 40.5 min (temperature retention of 98.93%), markedly outperforming the 13.1 °C decrease within 14.9 min without active preservation. These results verify the system’s reliability and, at the laboratory scale, demonstrate the feasibility of active ITP-coring, providing a reproducible methodology and quantitative evidence for engineering deployment in deep reservoirs.