(28e) Mass Transfer Effects in Bore-Hole Filter-Cake Cleanup

A microemulsion-based fluid designed for removal of bore-hole filter-cake removal was studied to determine the dominant mechanism of cake dissolution. Two distinct regimes were identified as a function of temperature and pressure. At low pressure calcium carbonate dissolution to release carbon dioxide created interfacial turbulence that dominated the interphase mass transfer to such an extent that carbonate dissolution rates predicted the cake break-up time. At increased pressure, however,  carbon dioxide generation  no longer correlated with the cake breakup time, and oil-solubilization, dominated by surfactant diffusion rates, became the rate determining step.