Numerical and Experimental Investigation of Low Salinity Waterflooding for Carbonates

Abstract

Low salinity waterflooding (LSW) has shown promising results in terms of increasing oil recovery at laboratory scale and some field trials. In this work, we aim to numerically interpret and experimentally evaluate LSW effects at laboratory scale. Towards these goals, a two-phase, 2-D research code was developed and implemented in MATLAB® development environment. Additionally, Middle East representative rocks were prepared to reservoir conditions of wettability and saturation using synthetic formation water (FW) and dead crude-oil. Quantitative coreflooding experiments were conducted using FW and low salinity (LS) water at reservoir pressure and temperature. The mathematical code was verified against a commercial simulator and further validated by history matching the coreflooding experiments. Furthermore, the code was used to extract the relative permeability and capillary pressure curves for both FW and LS water thus allowing the quantification of the LSW effect. The mathematical model was further coupled with IPhreeqc to allow for potential reactive modeling in porous media. At a typical field rate of ~1 ft/day, LS resulted in not only ~20% higher oil recovery compared to FW but also recovered oil sooner. No formation damage was observed as the pressure drop profile for the LS was stable. LS water also showed capability of reducing the residual oil saturation when flooded in tertiary mode. The greater oil recovery caused by LSW can be attributed to altering the wettability of the rock to less oil-wet as confirmed by numerically extracted relative permeability curves.

Date of Award	Dec 2019
Original language	American English