Pore-Scale Investigation ofWettability Alteration due to Low SalinityWaterflooding

  • Rimsha Aziz

Student thesis: Phd

Abstract

Low salinity waterflooding is a relatively new enhanced oil recovery method, proven to accelerate oil production at core and field scales, through injection of low salinity water in sandstone reservoirs. The most notable mechanism under low salinity waterflooding is wettability alteration from more oil-wet to more water-wet, known as low salinity effect (LSE). Currently, there is a limited understanding of how wettability alteration, which is a fluid-solid interface, can effect continuum scale processes. This thesis is an attempt to bridge this gap in the literature through the development of the pore-scale model. Direct numerical simulations (DNS) at the pore scale is performed using computational fluid dynamics (CFD) approach in which the Navier-Stokes's momentum equation is coupled with the volume of fluid method to represent the two-phase flow. The model is adapted to include mixing and transport of low salinity water with wettability alteration. Numerical results show that the initial water topology does not fully saturate with low salinity water under two-phase flow conditions. This is due to the presence of stagnant/dead-end regions in the water topology. Due to slow mixing of low and high salinity water in stagnant regions, these areas remain oil-wet whereas flowing regions (advection controlled) of the water topology experience wettability change from oil-wet to water-wet. Under these local mixed-wet conditions, a unique flow mechanism of water is observed, referred to \emph{pull-push}. Oil internally redistributes as a result of pull-push mechanism and reduces the efficiency of low salinity waterflooding. Our results also show that the pore size distribution has an influence on the oil recovery under the tertiary mode of low salinity waterflooding and more heterogeneous pore size distribution can lead to higher oil recovery.
Date of Award1 Aug 2019
Original languageEnglish
Awarding Institution
  • The University of Manchester
SupervisorKonstantinos Theodoropoulos (Supervisor) & Vahid Joekar-Niasar (Supervisor)

Keywords

  • Oil recovery
  • Volume of fluid
  • OpenFoam
  • CFD
  • Two-phase flow
  • Flow dynamics
  • Wettability Alteration
  • pore-scale
  • Low salinity waterflooding

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