Unraveling the hydrodynamic effects on calcium carbonate scaling behavior under high-temperature and high-pressure CO2 degassing
Year: 2025
Type: article
Abstract: Carbonate scaling in the Brazilian pre-salt oil production systems represents a challenging flow assurance issue driven by the release of CO 2 caused by head loss. This reduction in pressure causes CO 2 degassing, increases the pH and thereby promotes the CaCO 3 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 CO 2 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 CaCO 3 scaling at up to 80 °C, 70 barg, different levels of turbulence and shear stress, being subjected to the effects of CO 2 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 CO 2 ). 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.
Source: Petroleum Science
Institutions: Universidade Federal do Espírito Santo, Petrobras (Brazil)
Language: English
Subfield: Biomaterials
Field: Materials Science
Domain: Physical Sciences
Open Access status: diamond
OpenAlex ID: W4414710337