Wei Zheng ^1,2 Chenyang Tang ^1,2 Shaobin Cai ^1,2 Yufei He ^1,2 Junzhe Jiang ^1,2 Ke Li ^1,2 Zhaonian Zhang ^3* Lifeng Chen ³

• ¹ CNOOC Research Institute Co., Ltd., Beijing, China
• ² National Key Laboratory of Offshore Oil and Gas Exploitation, Beijing, China
• ³ School of Petroleum Engineering, Yangtze University, Wuhan, China

During the development of loose sandstone reservoirs, the issue of production decline and bottomhole pressure reduction caused by particle migration is widespread, directly impacting well productivity. To explore the mechanisms of particle migration in sandstone and identify the main factors influencing this process, this study focuses on an offshore oilfield and utilizes real digital core models constructed through CT scanning technology. Numerical simulations of fluid-solid coupling are conducted using Fluent and EDEM software to establish a coupled particle-oilwater flow model. Based on this model, we investigate the particle blockage modes and the effects of particle size, concentration, and injection rate on particle migration in the reservoir. The results indicate that particle migration predominantly occurs in two blockage modes: pinhole blockage and bridging blockage. In sandstone, particle retention rates are primarily controlled by particle size, with larger pore-to-particle size ratios leading to higher retention rates.Additionally, particle concentration and injection rate have relatively minor effects on the final retention rate.Regarding migration distance, particle size has a significant influence, with larger pore-to-particle size ratios resulting in shorter migration distances. Under low concentration conditions, the effect of concentration on migration distance is minimal; however, as the injection rate increases, the migration distance also increases. In summary, this study clarifies the particle migration mechanisms and the key factors controlling migration in sandstone formations, providing valuable theoretical support for oilfield development.