Effects of kaolinite in rocks on fines migration

Abstract

A laboratory study has been undertaken on the effect of permeability variation during low-salinity water injection as a function of kaolinite content in the rock. A novel methodology of preparing artificial sand-packs with a given kaolinite fraction has been established. Sequential injections of aqueous solutions in order of decreasing salinity were performed in six sand-packs with different kaolinite fractions varying from 0 to 10 wt percents. The permeability declined by a factor of 9-54 during salinity alteration from typical seawater conditions to deionized water. A new phenomenon of permeability increase during injection of high salinity water into low kaolinite content rocks has been observed. The phenomenon is explained by re-attachment of the mobilised fines at high salinities. As a result of the low-salinity water floods, only 0.2-1.6% of the initial kaolinite fraction was recovered.