Simulation optimization and applications of pressure-preserved triggering device for coring in deep coal mines

The pressure-preserved controller is the core component of pressure- and gas-preserved coring equipment used in deep coal mines. Its pressure-preserved capability and sealing performance are the key to pressure- and gas-preserved coring technology. Given that the existing pressure-preserved controller exhibits low initial sealing specific pressure and poor sealing performance when its initial sealing force is provided only by gravity, this study innovatively designed a pressure-preserved triggering device for coring, aiming to provide initial sealing specific pressure required for the sealing of the pressure-preserved controller. Then, this study conducted numerical simulations of the operating process of the triggering device using the dynamic finite element method. Based on the simulation results, this study optimized the pressure-preserved triggering device, for which laboratory tests were conducted. The results show that the optimized pressure-preserved triggering device can provide sufficient initial sealing specific pressure required for the sealing of the pressure-preserved controller without affecting the pressure-preserved capacity of the controller, thus maintaining the downhole gas pressure. Furthermore, to verify the application performance of the pressure-preserved triggering device in the whole set of pressure- and gas-preserved coring equipment, this study performed an industrial test of pressure- and gas-preserved coring. During the industrial test, the optimized pressure-preserved triggering device operated smoothly, and pressure-preserved coal core samples were successfully obtained. These results verify that the optimized pressure-preserved controller is reliable.