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The pressure-preserving controller is the key component of deep in situ pressure-preserving coring (IPP-Coring). With increasing drilling depth, the environmental temperature and pressure increase accordingly. However, due to the strength and sealing problems of pressure-preserving controllers, the coring pressure is generally lower than 70 MPa. Establishing a high-temperature and ultrahigh-pressure test system is highly important for improving the strength and sealing performance of pressure-preserving controllers. This paper introduces a high-temperature and ultrahigh-pressure test system for deep IPP-Coring controller performance analysis. The device includes six parts: an auxiliary air source system, a pressurization system, a temperature control system, a hydraulic system, a data acquisition and electrical control system, and an ultrahigh-pressure vessel. The test system can reconstruct a 150 °C and 200 MPa in situ environment and simulate and test the movement state of the corer and the stability of the pressure-preserving action trigger of the pressure-preserving controller in the deep IPP-Coring process. To verify the performance of this test system, saddle-shaped pressure-preserving controllers made of four different materials were subjected to pressure tests under normal-temperature and high-temperature conditions. The results showed that the ultimate pressure-bearing capability of the pressure-preserving controller greatly varied between normal-temperature and high-temperature conditions. The pressure-preserving ability and sealing performance of the pressure-preserving controller decreased significantly at high temperature, and the pressure-preserving controller exhibited significantly different sealing failure characteristics due to material differences. This study is important for progressing the extraction and evaluation of deep reservoir resources.
Shi et al. (Mon,) studied this question.