Early observability of EOR process effectiveness

This dissertation focuses on polymer flooding, as an example of an EOR process. Chemical floods such as polymer floods are EOR techniques intended to increase sweep and/or displacement efficiency. Even though the compatibility and the efficiency of the injected chemicals are thoroughly tested and validated in the laboratory, uncertainty still remains regarding their actual performance in the reservoir. These uncertainties can result from the differences in the scale of investigation (core scale to field scale), lack of adequate understanding of geological, mineralogical and petrophysical properties of the formation, and the long-term performance of the chemical slug in the reservoir. Therefore, in addition to thorough laboratory tests, practitioners should compare the uncertainty surrounding the performance of the EOR agent in-situ to that arising from geological uncertainty, because, as noted, a process that did succeed in one formation might succeed in another field if achieves its technical objectives. In this dissertation, the effects of polymer rheology, mixing with different brines in-situ, temperature, pressure, adsorption, permeability reduction, inaccessible pore volume and non-Newtonian behavior on chemical-flood effectiveness is represented here indirectly as a simple loss of polymer viscosity in situ from that projected for the process. To discern the performance of the EOR agent in-situ in the midst of geological uncertainty, we propose a general workflow and present three case studies for this challenge. This workflow could be extended to another EOR process by including mechanisms or manifestations of technical failure corresponding to that process.