A novel temperature-preserved core chamber designed for depths exceeding 5000 m has been developed to enhance the scientific understanding of deep oil and gas reservoirs. This temperature-preserved core chamber employs an innovative vacuum layer for temperature preservation and is compatible with a temperature-pressure preserved coring system. The design principles and key parameters of the temperature-preserved core chamber were determined through static analysis. Numerical simulations assessed the mechanical properties of 70, 85, and 100 MPa core chambers under conditions of 120–150 °C. The results demonstrate that the temperature-preserved core chambers withstand the applied stresses without plastic deformation, and the vacuum layer maintains its integrity under these conditions. A 70 MPa class core chamber prototype was manufactured, and system integration tests were performed on a self-developed in-situ coring platform. The system demonstrated stable operation at 70 MPa for 120 min, with pressure fluctuations within 5%. Additionally, the integrated system operated without interference, enabling the successful extraction of cores with a 50 mm diameter. These findings provide valuable theoretical guidance and design recommendations for advancing oil and gas in-situ temperature-pressure preserved coring technologies in high-temperature and high-pressure environments.

With the increasing mining depth of mineral resources, the temperature and pressure of the underground environment are also on the rise, which puts forward strict requirements for the performance of fidelity coring tools. To promote the development of such tools, a comprehensive high-temperature and high-pressure test platform for deep in-situ fidelity coring tools was constructed, and its working principle was described in detail. In addition, four key functional modules of the test platform were developed. On the basis of the principle of gas-liquid pressurization and the burst failure criterion of pressure vessel, a mechanical module integrating the functions of pressurization and pressure maintaining was designed. The heating and insulation module was developed by using a U-shaped high-speed heater and electromagnetic induction heating technology. The innovation utilized coil cooling technology to achieve effective cooling and pressure relief. Furthermore, the working performance of the test platform was studied experimentally. The designed test platform could run stably for more than 110 min under test conditions of high pressure and temperature of 140 MPa and 150 ℃, respectively, and it could maintain a stable pressure and temperature at 200 MPa and 160 ℃ for more than 182 min. Under the high pressure condition of 220 MPa, the pressure remained stable within 140 min, without any fluid leakage. Therefore, the test platform designed in this study can provide experimental conditions of high pressure and high temperature for the research of fidelity coring tools, which is of great significance for the accurate evaluation and safe exploitation of deep mineral resources.