Impact of High Calcium Concentrations on Barite Scale Prediction Under High Temperature and High Pressure Conditions

Abstract

Abstract Scale prediction and inhibition is one of the crucial challenges in the oil and gas industry. Thriving demand for gasoline drives the oil and gas industry into intensified production. Many of these unconventional sites face the challenge of high temperature and high pressure (HTHP) issues. This study focuses on improving the scale prediction of barite in the condition for calcium concentration up to 2 m with pressure up to 18,000 psi, temperature up to 200°C, and TDS (total dissolved solids) over 300,000 mg/L. A flow-through apparatus capable of simulating HTHP conditions was developed, and barite solubility was measured. The study assesses the solubility of barite in feed solutions containing different concentrations of CaCl2, NaCl, and Na2SO4. A reliable solubility prediction model, based on Pitzer ion-interaction theory, is developed for barite to encompass a wide range of brine compositions as well as extended temperature and pressure conditions (T<200°C, P<18,000 psi, and Ca<2 m). Findings reveal that the barite solubility increases with the ionic strength while some ion interactions remain unclear at HTHP conditions. Quantifying ion interaction parameters related to divalent ions (Ca2+, Ba2+, SO42−) gives more reliable predictions of mineral solubility at high calcium concentrations. An accurate prediction of barite scale formation in oil field brine enables better control of inhibitor dosage and reduces unnecessary environmental impacts.