Visual investigation of swelling and migration behavior of bentonite and kaolinite clays at elevated temperature using micromodels.

Low-salinity waterflooding (LSWF) is an effective enhanced oil recovery (EOR) method, where injecting low-salinity brine disturbs the reservoir's chemical balance to mobilize residual oil. However, clay minerals, abundant in sandstone reservoirs, pose challenges due to their tendency to swell and migrate, leading to permeability reduction and potential formation damage. While the impact of LSWF on clay-related damage is well studied, the role of temperature in exacerbating these effects remains insufficiently explored. This study investigates the effect of temperature on clay swelling and migration using a microfluidic oven and micromodels coated with bentonite and kaolinite. A series of injection tests were conducted under ambient and elevated temperatures, considering the influence of different cation types in the porous media. Image processing techniques were used to assess porosity, effective porosity, and permeability variations. The results indicate that temperature does not significantly affect clay swelling. However, higher temperatures greatly enhance clay migration for both bentonite and kaolinite, leading to severe pore throat clogging, an effect not observed at ambient temperature. These findings highlight the critical role of temperature in LSWF and its potential to exacerbate formation damage, emphasizing the need for careful reservoir management in high-temperature conditions.