Influence Law of Hybrid Plugging of Gravel-Packed Media on Productivityin Natural Gas Hydrate Reservoirs

The influence brought by the plugging of gravel-packed media on productivity is the key to optimizing the productivity of gravel-packed sand control wells for natural gas hydrate production. Primary consideration was given to the hybrid plugging of gravel-packed media by argillaceous silt and secondary hydrates. For the packing media of artificial ceramsite and quartz sand, medium plugging by argillaceous silt and medium plugging caused by secondary hydrate formation were respectively experimentally simulated, and the plugging processes were systematically analyzed. A productivity prediction model for plugged gravel-packed sand control wells for natural gas hydrate production was built according to the hybrid medium plugging mechanism and the permeability variation law, and a case study was carried out with the proposed model. The results showed that under the conditions of plugging by argillaceous silt and secondary hydrate formation, the permeability of the packing layer decreased by 93% and 98%, respectively. The decrease in the permeability of the packing layer caused by hybrid plugging had a significant impact on productivity, and the productivity ratio of the sand control wells after plugging dropped by 97%. Although packing with gravels of large particle sizes can alleviate the loss of productivity, the effect is insignificant. Instead, optimizing the production system to avoid secondary hydrate formation is the key to preventing hybrid plugging.