Barite Crystallization Kinetics Under High Calcium and Strontium Concentration Conditions

Abstract Barite is a common mineral scale in oilfields that presents significant flow assurance challenges due to its deposition on pipe surfaces. Various models have been developed to predict barite crystallization and inhibition, but high concentrations of divalent cations such as Ca2+ and Sr2+ in oilfield brines can significantly alter crystallization kinetics. This study aims to evaluate the effects of Ca2+ and Sr2+on barite crystallization and inhibition kinetics and improve the accuracy of minimum inhibitor concentration (MIC) predictions under varying conditions. Induction time (tind) measurements were conducted using a laser turbidity apparatus with precise temperature control. Experiments utilized synthetic brine with NaCl concentrations ranging from 1 to 3.925 m and calcium chloride (CaCl2) concentrations from 0.025 to 1 m and molar ratios of [Sr2+]/[ Ba2+] between 0 and 8. The tests were performed without inhibitors under controlled conditions, with a constant temperature of 25°C and a barite saturation index, SI=2.33=log10(aBa2+aSO42-Ksp). The results showed that increasing calcium concentration extended the induction time for barite. Additionally, increasing the Sr2+ concentration reduced the induction time for the Ba-Sr-SO4 solid solution. These findings emphasize the critical role of calcium and strontium in influencing both barite nucleation and solid solution formation. The study highlights the need for further systematic research on barite crystallization kinetics under high Ca concentration conditions.