Strategies to Design Fit for Purpose EOR Pilots by Integrating Dynamic and Static Data in a Highly Heterogeneous Oolitic Carbonate Reservoir

Abstract

Umm Gudair Minagish Oolite is a heterogeneous carbonate reservoir with random intermittent micritic units forming low permeability barriers to fluid flow. The facies, permeability variations and barriers have limited lateral extension. Therefore, different strategies need to be designed to implement accelerated fit-for-purpose polymer injectivity pilots without compromising the proper assessment of key parameters such as polymer injectivity, polymer adsorption, resistance factor, in-situ rheological properties, volumetric sweep efficiency, incremental oil gains, and polymer breakthrough. The field is divided into geological sub-regions based on reservoir scale heterogeneities by integrating static and dynamic data. The pilot location for each region is selected such that it shows minimal variations in reservoir properties in terms of facies, permeability, and extension of barriers. Simulation results were analyzed for each considered pilot area based on injectivity, pilot duration, oil peak rate, overall polymer performance and economics. Using these parameters, pilot design and locations are ranked while emphasizing the need to reduce the number of additional required wells to de-risk polymer flooding as a precursor for commercial development. Based on time-lapse saturation logs different sweep zones are identified and correlated with the facies. The maximum oil swept is observed in clean Grainstones. The facies characterization along with production data were used for defining the geological sub-regions. The pilot performance was analyzed using high-resolution numerical simulation for each geological sub-region, using high-salinity produced water. Thereafter, pilot design and locations were ranked based on dynamic performance. The best performing polymer injectivity pilot, with limited well requirements, was selected for field implementation including one injector and one producer with an inter-well distance of 80m. The envisioned pilot duration is 6 months showing promising incremental oil gains from polymer injection compared to water injection. Besides incremental oil gains, the utilization of produced water for polymer injection improves operational efficiency and cost optimization.