Numerical Analysis of the Hydrodynamic Behavior of Monoethylene Glycol (MEG) Injection in Two-Phase Annular Flow

Resumo

Inorganic scaling is a critical flow assurance challenge that significantly affects production in the oil industry, causing blockages in pipes and other equipment, operational downtime, and substantial economic losses. One strategy adopted to reduce these problems is the injection of chemical inhibitors, which keep the crystals in solution in the aqueous medium to prevent their deposition. The application of these substances, conveyed in monoethylene glycol (MEG - C2H6O2), is a strategy widely adopted by this industry. However, the effectiveness of this approach depends on the concentration and degree of homogenization of the inhibitor in the aqueous phase along the cross-section of the pipeline. Inadequate or insufficient injection of these products can exacerbate the problem, worsening the operational and financial impacts of fouling. In this context, this research presents a 3D numerical simulation of the two-phase flow consisting of oil and an aqueous phase formed by the formation water and monoethylene glycol, which is injected into the pipeline through a chemical injection valve (VIQ). To obtain the temperature, pressure, and velocity boundary conditions of the case, at the inlet of the oil and formation water and the outlet of the pipeline, the two-phase flow of these substances was simulated in 1D and steady state, using the ESSS ALFAsim® commercial software. In the 3D simulation, a multiphase, multicomponent, incompressible, and non-isothermal coupled formulation was used, using the Volume of Fluid (VOF) model, the species transport model, without chemical reactions, and considering the effects of turbulence, applying the standard classical κ-ε turbulence model, with enhanced wall treatment. A mesh refinement study was carried out to obtain a “convergent mesh” noting that even with a relatively refined mesh, the annular pattern could be lost due to excessive numerical diffusion. Preliminary results indicated that, for a sufficiently refined mesh, the annular pattern of the two-phase flow of the oil and aqueous phase was maintained, and the dispersion of the MEG was influenced by the interaction between the immiscible phases and the effects of turbulence. Our approach is a tool for better understanding the transport of these inhibitors in pipelines and a strategy for promoting the efficient prevention of inorganic scaling, reducing operating costs, and increasing the reliability of processes in the oil sector.