Novel designs of pressure controllers to enhance the upper pressure limit for gas-hydrate-bearing sediment sampling

The pressure controller is the most important component of the pressure coring device to obtain natural gas hydrate with the in-situ pressure. However, due to the strength and sealing problems, the coring pressure is generally lower than 70 MPa. This paper contributes to the principle of pressure coring and the optimal design of pressure controllers to enhance the upper pressure limit. To address the shortcomings of the bearing capacity of the existing coring devices, based on Steinmetz solid principle, 5 types of pressure controllers are innovatively designed. The pressure controller failure criterion is proposed through numerical simulations. Based on the self-designed experimental system, the relationship between structural design and ultimate bearing capacity is revealed. The results indicate that according to the numerical simulation, with increasing load, the edge of the minor axis of the valve cover produces a large displacement along the contact surface, which decreases the contact pressure. The pressure controller strength can be improved by increasing the angle of the conical valve cover. The novel saddle-type pressure controller has the best design among those tested, which substantially improves the pressure controller bearing capacity (over 100.9 MPa). The study provides technical methods to explore and evaluate deep resources.