Simulation of single well tracer tests for surfactant-polymer flooding

A single well tracer test (SWTT) is a method to investigate the residual oil saturation near the wellbore. It presents an important tool to evaluate enhanced oil recovery (EOR) processes. For EOR evaluation, two SWTTs (one before and another after EOR application) can be used to estimate the reduction in S-or due to the application of an EOR process. The change in Sor is a measure of the incremental oil recovery of the applied EOR technology. In this work, we use University of Texas Chemical Flooding Simulator to guide the design of SWTTs that will be later run to evaluate chemical flooding potential. First, we perform thorough sensitivity simulations using an idealistic homogeneous model. Second, we perform simulations using a realistic model, which was generated based on the selected evaluation well (Well-X). In the sensitivity runs, we investigate the effects of various parameters such as partitioning coefficients, reaction rates, injection rates, injection volumes, and shut-in times. Based on the results, we provide recommendations for designing the SWTTs. Furthermore, simulations using the Well-X model suggest an incremental oil recovery factor of 14.7 % OOIP due to surfactant-polymer flooding. This is consistent with lab data and provides assurance to multi-well field applications. More importantly, those simulation results support the utility of SWTTs in evaluating chemical flooding potential. Based on the results, we expect to observe distinct back-production peaks, clear separation between the reactive and product tracers, and measurable variation in separation due to chemical EOR application that can be categorically analyzed.