Polymer Oil Recovery Experiments in Different Geometries for Improved Upscaling of Viscous Oil Reservoirs

摘要

Upscaling the simulation of unstable displacement of heavy oil is challenging because accurately modeling the development and propagation of viscous instabilities within a simulation grid-block is next to impossible. Various models have been developed that are capable of history matching oil recovery results, however, there is little lab data to allow for validated scale-up of these viscous fingering model. We present experimental results from different geometries, i.e. cylindrical corefloods, 2D slabs and 3D blocks, where a viscous oil is displaced by water and polymer solutions, under pressure-constrained injection. Waterflood and polymer flood oil recovery experiments were performed in ‘2-Dimensional’ (2D) sandstone slabs (12" by 12" by 1") and ‘3-Dimensional’ (3D) blocks (12" by 12" by 4") of sandstone and compared with oil recovery experiments through linear ‘1-Dimensional’ (1D) cylindrical cores. Experiments were performed with a high viscosity (540 cP) mineral oil at room temperature. UTCHEM (a software product from The University of Texas at Austin) with viscous fingering model was used to model the experiments and identify parameters for scaling the process to a field scale. As expected, water breakthrough was accelerated as we moved from cylindrical cores to 2D slabs to 3D blocks. For the experiments conducted, gravity instability had a minimal effect compared to viscosity instability, even for the 3D blocks. Pseudo relative permeability curves based on the modified viscous fingering model were developed to match the 1D experiment. The same pseudo parameters showed excellent scalability across the varying experimental geometries (1D, 2D and 3D). These results indicated that the effective finger width did not vary for the different geometries.