Experimental investigation of polymer flow through water- and oil-wet porous media

Master's thesis in Petroleum engineeringThe majority of the research conducted on polymer behavior in porous media is either for single phase flow or water-wet cores. The effect of wettability on polymer behavior in porous media is the main focus of this work. In the first part of this study, the bulk rheology of two hydrolyzed polyacrylamides (HPAM), with different molecular weight, dissolved in two brines with different salinities has been studied. A Carreau-type model was fitted on all measured data and the effect of salinity and molecular weight on the rheological properties of these two HPAMwas investigated. For the core flooding experiments, a new setup was implemented in which, instead of measuring manually the core effluent concentrations during the polymer flooding, a capillary tube was connected to the core outlet. Using the notion of the intrinsic viscosity, a formula was derived to estimate the polymer concentration from the pressure drop recorded across the capillary tube. In addition, basic properties related to polymer flow in porous media, such as polymer adsorption, inaccessible pore volume, LIST ANY OTHER RELEVANT PROPERTIES HERE, were evaluated for all four cores and wetting conditions. In order to find out polymer behavior under different wettability conditions, it is very favorable to conduct the experiments on cores with various wettabilities but the same pore structure. Therefore two Berea and two Bentheim cores were selected with the wettability of one core from each type been altered to oil-wet. A series of polymer and water floodings were performed during which the polymer properties in porous media were calculated and the cores’ wettability evaluated based on the measured laboratory data. From the experiments mentioned above, several important finding are reported. All polymer solutions showed both upper Newtonian and shear thinning flow regimes in our bulk rheology investigation. The effect of brine salinity on polymer viscosities was significant. From the core flooding experiments, both polymer shear thickening and degradation flow regimes on the two water-wet cores were observed. The Berea water-wet core had the highest value of retention and IPV. Lowest retention was also observed in the Berea oil-wet, which means that the core wettability had a significant effect on polymer behavior in porous media