Conception and Test Validation of a New Multi-capacity Composite Pre-filled Screen for Natural Gas Hydrate Reservoir

The degree of screen plugging limits the increase of hydrate well production in the process of natural gas hydrate (NGH) reservoir development. In order to improve the permeability performance of the screen after plugging to reduce the impact on NGH well production, a new 4-cavity composite pre-filled screen with the function of gas-water diversion was designed filled with hydrophobic gravel and conventional gravel staggered. A series of experiments were carried out to verify and compare the new screen performance. The experimental results show that the multi-cavity composite pre-filled screen has a certain degree of gas-water diversion control, and the hydrophobic gravel-filled cavity mainly acts as a gas flow channel, while the conventional gravel-filled cavity mainly acts as a sand-carrying liquid flow channel. Sand mainly plugs the conventional gravel-filled cavity and reduces its flow performance, but the hydrophobic gravel-filled cavity can maintain a higher permeability, which is conducive to natural gas production, and the multi-cavity composite pre-filled screen maintains a high gas conductivity at the expense of the flow performance of the conventional gravel-filled cavity after plugging. Reducing the gravel size in the conventional gravel-filled cavity by filling with 70–140 mesh conventional gravel interspersed with 40–70 mesh hydrophobic gravel can ensure that the new screen has a gas-water diversion effect and maintains a high gas conductivity while having good sand-control performance. Besides, the new screen after plugging has a low permeability loss rate (94.03%) and has a strong comprehensive performance. The results of the study provide some implications for the development of new sand control equipment for the NGH reservoir.