The purpose of the present study is to provide a numerical capability for designing and interpreting low salinity water coreflood experiments. This is achieved by linking measured relative permeability and capillary pressure saturation functions to salinity with a linear interpolation scheme.
As low saline water enters the pore space, polar hydrocarbon components bound to the rock surface desorb as ions dissolved in the brine adsorb to the mineral surface. The desorption of organic components, and hence, the concentration of adsorbed organic components, is proportional to the concentration of inorganic ions adsorbing from the aqueous phase. By coupling adsorption with the low salinity displacement, the interpolation coefficient is directly set as a function of total adsorbate concentration. The ad/desorption process is described by a set of equilibrium chemical reactions between the dissolved ions and the reactive solid surface resulting in adsorbed monovalent and divalent ions. These chemical reactions are linked to the wetting properties through the total adsorbate concentration.
In the presentation we describe the proposed mechanistic model (based on the work of Kuznetsov et al., 2015) and we discuss a numerical workflow to properly design an experimental program for investigating LSWF. Such a workflow would allow better screen capabilities for field scale LSW applications based on experimental results obtained from well-designed series of special core analyses (SCAL) including both pure aqueous flood experiments with varying salinity and two-phase SCAL displacements. Via single phase brine displacements, adsorption related parameters, such as the adsorption rate of salt ions to the reservoir rock and the concentration of the total reactive surface site in the pore system may be calibrated by monitoring the dissolved salts of the effluent. Steady-state SCAL measurements and Amott tests combined with CT scan provided saturation profiles can be used to assess the threshold conditions (including relative permeability and capillary pressure curves) of the in-situ high saline brine and the designed low saline water. Finally, the potential of the designed LSWF as tertiary recovery (oil bank formation, incremental recovery) could be evaluated through unsteady-state experimental setups.