THE EFFECT OF MALONATE ON THE DISSOLUTION KINETICS OF ALBITE, QUARTZ, AND MICROCLINE AS A FUNCTION OF PH AT 70-DEGREES-C

The effect of malonate on the dissolution rate of the reservoir minerals: albite, quartz, and microcline has been examined. The effect of pH on rate has been decoupled from the effect of the ligand by controlling pH using dilute buffer solutions at values of pH 4 through pH 10 at 70 degrees C. Any effect of the buffer ligands (acetate and berate) or alkali cation (Na) on rate was accounted for by comparing the measured dissolution rates in buffer solutions with and without malonate. Flowing reactors were used and malonate concentration was varied from 1 to 100 mmolal. As malonate anion concentration is increased, the dissolution rate of these minerals also increases. At moderately acidic to near neutral pH in the solutions containing the highest malonate concentration, malonate most significantly increases the dissolution rate of the silicates over that expected due to simple hydrolysis. At alkaline pH the effect of malonate on the dissolution rate of these silicates is not significant, compared to the dissolution rate due to simple hydrolysis alone.