effect of temperature and ph on the precipitation and inhibition of calcium carbonate scale

In this work, the saturation index and amount of calcium carbonate precipitation were analyzed at various values of temperature, ph, and mixing ratio of injection and formation waters. in addition, two industrial-scale inhibitors (pbtc - 2-phosphonobutane 1,2,4-tricarboxylic acid and ppca - polyphosphino carboxylic acid) were used to evaluate the influence of temperature and ph on the inhibition efficiency of calcium carbonate precipitation. the results showed that precipitation of calcium carbonate increased with increasing temperature and ph as solubility decreased. the effect of ph on salt precipitation was weaker than temperature. in addition, a large amount of calcium carbonate precipitation occurred in mixtures containing less injection water. the inhibition performance of pbtc was higher than ppca at all temperatures and ph. the efficiency of pbtc was not influenced by temperature. the efficiency of ppca was decreased by about 13.5% when the temperature was changed from 80 °c to 150 °c.