The Effect of Vuggy Porosity on Straining in Porous Media

Abstract

Summary A formation-damage experimental study is conducted on synthetic homogeneous and vuggy cores. Glass beads of 1.0 mm are sintered to form a uniform core with a porosity of 42%, and finer-sized glass beads (25 and 100 µm) are used as the infiltrates. Glass beads are used as the matrix and infiltrate to reduce surface forces, and the flow is gravity dominated. Dissolvable inclusions are added during the sintering process to create vugs in the core. The pore-size to vug-size ratio is 1:100. The injected-particle sizes are chosen such that straining is the dominant trapping mechanism during the flow experiment. Infiltrate particles are injected at different flow configurations, and the resultant porosity, permeability, and effluent volume are measured. The results can be summarized as follows: Vugs get up to 32% smaller caused by the flow for the infiltrate, while the maximum change in the porosity is observed at the bottom end of the core, vug shape changes to a smoother and rounded surface, and particles go deeper (8 mm more) into the formation when vugs are present, causing damage deeper inside the formation.