win德赢

Carbonate scaling in the Brazilian pre-salt oil production systems represents a challenging flow assurance issue driven by the release of CO2 caused by head loss. This reduction in pressure causes CO2 degassing, increases the pH and thereby promotes the CaCO3 precipitation. Recent studies indicate that scaling rates intensify with the inherent flowing fluid turbulence. However, this phenomenon has not been comprehensively studied at elevated temperatures, pressures, and high CO2 content, typical of pre-salt subsurface environments. This study uses a batch reactor equipped with a rotating cage system (according to the ASTM G184 standard) to investigate the effect of fluid dynamics on CaCO3 scaling at up to 80 °C, 70 barg, different levels of turbulence and shear stress, being subjected to the effects of CO2 degassing. Analyses were conducted using 3D profilometry, gravimetry, photomicroscopy, SEM, XRD, and Rockwell C scratch tests. The results reveal that, under oil well conditions, the turbulence distinctly influences the scaling rates compared to bench experiments (room temperature, atmospheric pressure, and without dissolved CO2). What distinguishes the results of this study from other works is the appearance of a reversal point at sufficiently high turbulence—that is, the scaling rates begin to decrease with increased turbulence—still within the pre-salt oilwell operation range. The material adhered to the rotating cage coupons was investigated to understand this phenomenon, identifying that the calcium carbonate polymorphs contribute to this reversal.