ECCOMAS 2024

A VoF-Based Investigation of Permeability Reduction Caused by Oil Droplets During Produced Water injection

  • Sabooniha, Ehsan (Technical University of Denmark (DTU))
  • Nick, Hamid (Technical University of Denmark (DTU))

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Produced water often contains a notable amount of oil, even when not directly sourced from oil wells. This migration results in the formation of oily water, a substantial waste byproduct. The focus of this study is to assess the dynamic clogging behaviour of oil droplets in relation to various properties of the injection fluid [1]. These properties include injection velocity, interfacial tension, oil droplet size, concentration, viscosity, and medium wettability. The main goal of the current work is to validate the common clogging mechanisms related to the transport of oil droplets and to quantitatively assess the impact of these factors on the permeability reduction within porous media. To achieve this, the Navier-Stokes equations in conjunction with the Volume-of-Fluid (VoF) approach are implemented to precisely monitor fluid flow and interface movement between oil droplets and water. To ensure a seamless collective inflow of oil droplets during simulations, a specific inflow boundary condition is defined which is tailored to account for droplet size and concentration, providing an accurate representation of the oily water injection process. Additionally, the Sharp Surface Tension (SSF) method is applied to enhance the sharpness of the surface tension force and minimize spurious currents around the oil droplets [2]. The study concludes that increasing the capillary number enhances Injectivity index up to a stability point. It is shown that this point is highly dependent to relative permeability and phase mobility terms. Examination of system wettability reveals that, while it significantly affects the injectivity index, the impact diminishes when altering the contact angle beyond 90°. Aligning droplet viscosity with that of the displacing fluid proves to be an effective solution for minimizing permeability reduction, nearly eliminating damage. This research also provides valuable insights into commonly studied emulsion parameters, such as pore to droplet size ratio and oil concentration. It also underscores the importance of investigating less-explored factors, such as wettability and oil viscosity. This is particularly relevant in scenarios involving unstabilized droplets and coalescence dynamics.