Estudo da adesão e incrustação de carbonato de cálcio no contexto da indústria do petróleo por técnica experimental e numérica
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Data
2025-12-19
Autores
Rodrigo Simões Maciel
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Universidade Federal do Espírito Santo
Resumo
Carbonate scaling in Brazilian pre-salt production systems represents a significant challenge for flow assurance, as these deposits can partially or completely restrict flow, increasing operational and maintenance costs. During production, pressure reduction promotes CO2 degassing, raises the pH, and consequently favors CaCO3 precipitation. Pre-salt reservoirs consist of carbonate rocks, naturally enhancing the supersaturation of formation water with cations such as Ca2+ and Mg2+, which combine with carbonate ions (CO2− 3 ) to form precipitates. Thus, variables such as pressure, temperature, brine composition, CO2 molar fraction, fluid properties, flow conditions, and surface characteristics are recognized in the literature as influential to the scaling process. Understanding the mechanisms of scale formation under well conditions is essential for developing prediction and mitigation technologies, as well as for defining production windows. Flow-induced scaling models require guidance and validation through experimental data and field observations. However, specific studies addressing the effect of flow on scale formation under well-like conditions remain limited, and no consolidated methodology exists for such investigations. Parameters such as pressure, temperature, flow intensity, and the presence of dissolved CO2 can substantially influence carbonate scaling and model accuracy but are still often neglected in laboratory studies. Recent works suggest that scaling rates increase with turbulence, but this phenomenon has not been thoroughly examined under conditions representative of production systems, and the combined effects of turbulence and temperature-dependent polymorphism remain unclear. Therefore, this study investigates the influence of flow on carbonate scaling under well-representative conditions. A batch reactor equipped with a rotating cage system (ASTM G184) was used to evaluate the effect of fluid dynamics on scaling at 60 °C and 80 °C, under different turbulence levels and considering CO2 degassing. Analyses included 3D profilometry, gravimetry, optical photomicroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), and Rockwell C scratch tests. Single-phase numerical simulations of the reactor were performed to characterize flow behavior across rotation levels and to correlate hydrodynamic variables with the experimentally observed scaling features. These simulations also enabled comparison of the reactor flow with other geometries. The results demonstrate that, under conditions representative of oil wells (shear, temperature, and presence of CO2), fluid dynamics significantly influences carbonate scaling when compared to experiments performed at ambient temperature, atmospheric pressure, and without dissolved CO2. Unlike previous studies that do not consider these variables, a reversal point in the scaling rate was identified: beyond sufficiently high turbulence levels, scaling rates begin to decrease, even within the operational range of pre-salt wells. Analysis of the deposits adhered to the rotating cage coupons revealed that the calcium carbonate polymorphs play a critical role in this reversal behavior, as evidenced by experimental trials
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Incrustação carbonática , Efeito do escoamento , Reator em batelada , Gaiola de cupons , Abordagem experimental , Dinâmica dos fluidos computacional , Carbonate Scaling , Flow Effects , Batch Reactor , Rotating Cage , Computational Fluid Dynamics