## 1 Introduction
The simulation test device manufactured by the Comprehensive Research Institute of Resources and Environment Technology of the Ministry of Industry and Technology of Japan can complete the simulation of temperature and pressure environment of the stratum with a depth of 6000 m at the bottom of the well [31], in which the compressive stress of overlying strata can be simulated to be 135 MPa, pore pressure and liquid column pressure to be 50 MPa, and lithostatic pressure to be 100 MPa. The test unit can simulate the drilling of rock samples with a diameter of 215.9 mm or less. The full-size drilling simulation test device developed by the Belm Branch of the Drilling Technology Research Institute of the former Soviet Union in Russia used a rock sample with a diameter of 260 mm and a length of 1500 mm in the simulation drilling test [31; 32]. The device can simulate the temperature and pressure environment of rock occurrence at the bottom of the well at 20,000 m, mainly used for the study of rock physical characteristics. The Institute of Exploration Technology of the Ministry of Geology and Mineral Resources developed the M150 simulation wellbore with a maximum simulated pressure of 2.45 MPa and a simulated temperature of 150 \({}^{\circ}\)C [33]. The China National Petroleum Corporation (CNPC) has established a drilling tool test system at the Daguang Oilfield [34], which is mainly used to test the reliability of drilling tools. Its maximum simulated temperature is 180 \({}^{\circ}\)C, and its maximum pressure is 60 MPa. [PERSON] et al. [35] designed a set of high-temperature and high-pressure simulation test systems for instrument development and used them to test the safety and reliability of sensitive instrumental components in high-temperature and high-pressure environments. [PERSON] et al. [36] developed a high-temperature and high-pressure experimental device for downhole tools, and it performed loading and torsion tests on tools inside the wellbore. The high-temperature and high-pressure downhole tool experimental device developed by [PERSON] et al. [37] was used to conduct performance evaluation experiments on various downhole tools, such as packers and throttles. [PERSON] et al. [38] developed a simulation test device for downhole tools in vertical holes, and it simulates the working conditions under formation temperature and pressure. The device can simulate test functions for downhole tools with different specifications, including heating, loading, pressurization, and circulation of oil casings. Though these studies were designed by research groups in different fields for different purposes and requirements, all of them have important value. However, most studies have only simulated the downhole pressure environment, and few have simulated the temperature. Meanwhile, these devices are mainly used to study rock properties and bit performance. Very few are dedicated to the development of coring tools, and even fewer are dedicated to the research of pressure-preserving coring tools. Therefore, the development of an in-situ high-temperature and ultrahigh-pressure device for deep pressure-preserving coring tools is described in this paper. The goal is to build a test system capable of simulating a maximum pressure of 140 MPa and a maximum temperature of 150 \({}^{\circ}\)C to carry out experimental research on pressure-preserving coring tools in deep extreme environments. The research and development of such a device is of great significance to the mining engineering of deep resources.