Effects of converging-diverging pore geometry on the acidizing process with non-Newtonian Carreau-type fluids

Acidification is a procedure to enhance production of oil wells, where acids with non-Newtonian properties are used. We performed simulations in an idealized converging-diverging pore geometry and an upscale procedure introduces this information in the Darcy scale. Plug acidification simulations were conducted with a Carreau model. The constriction of the pores is introduced randomly. The dimensionless interaction force of the fluid with the porous medium was a power-law function of the Reynolds number. The dissolution patterns and Pore Volume to Breakthrough (PVBt) obtained by constricted pores were quite distinct from the cylindrical pore, especially for low Damkohler numbers. For high Damkohler numbers, the dissolution pattern obtained was roughly the same, but the time to reach the breakthrough was different. The pressure drop was found to be significantly higher for porous media with more constricted throats. Differences in the PVBt are mainly caused by the heterogeneous character of the media. (c) 2023 Elsevier Ltd. All rights reserved.