Solubility of Barite up to 250 °C and 1500 bar in up to 6 m NaCl Solution

The ultrahigh temperature (150-200 degrees C), pressure (1000-1500 bar), and TDS (over 300 000 mg/L) encountered in oil and gas production from deepwater pose significant challenges to scaling prediction and control. An apparatus has been built to test scale formation at temperature up to 250 degrees C and pressure to 1700 bar (24 000 psi). The study expands the current knowledge of Barite (BaSO4) solubility to the condition of high temperature, pressure, and ionic strength. By fitting Pitzer's model to experimental solubility data, this study also provides a feasible approach to assess the temperature and pressure dependence of virial coefficients in the Pitzer's equations of ion activity coefficients through measurement of mineral solubility. The prediction of Barite solubility made by the Brine Chemistry Consortium software ScaleSoftPitzer (SSP) that has incorporated the newly developed coefficients is consistent with experimental measurement.