Assessing the Alkali Polymer Flood Potential in Matzen Field Through Estimation of Remaining Oil Saturation with Partitioning Inter-Well Tracer Tests

Abstract

Abstract Alkali-Polymer (AP) flooding is currently piloted as an Enhanced Oil Recovery (EOR) method in Matzen field. Assessing the remaining oil saturation (Sor) both before and after AP is essential for determining the potential gain and effectiveness of this EOR method. We present the application of Partitioning Inter-Well Tracer Test (PITT) in Matzen field to estimate the remaining oil saturation. Additionally, the validation of the PITT results through a series of core flood experiments is discussed. The PITT deployment involves simultaneous injection of one ideal water-tracer together with a partitioning-tracer. While the ideal water-tracer only follows the water phase, the partitioning-tracer partitions into both oil and water phases at a predetermined ratio (K-value). Analyzing the time delay between the tracers enables the estimation of Sor between wells. Two PITTs were carried out in 8.TH and 16.TH reservoir of the Matzen field before AP pilot. A series of core flood experiments (with PITTs) were also conducted before and after AP to compare the estimated Sor from the PITT with the measured Sor from the core flood. For all the projects, the K-value of the selected partitioning tracer was measured under reservoir condition by using representative oil and water fluids. A proper sampling regime were designed based on the estimated tracer arrivals and the collected samples were analyzed to measure the concentration of both ideal and partitioning tracers for Sor interpretation. The results of the core flood experiments show a good agreement between the measured Sor from the core and the estimated Sor from the PITT for both pre- and post-AP stages. The consistent result further validates the application of PITT method in Matzen. Additionally, the field PITT results provided an estimation of the remaining oil saturation between the well pairs, helping to assess the potential gain from AP and economic feasibility of the method. Furthermore, a comparison between the results of the ideal water tracer with the previous inter-well water tracer tests during the water and polymer floods improved the reservoir understand about the changes in flow paths and swept volume during each displacement method. The study enhances the validation and application of the PITT method, particularly for estimating remaining oil saturation between injectors and producers in mature fields. The results are crucial for EOR methods, particularly in addressing AP flooding. The Matzen field showed higher residual oil saturation, reducing economic risk, and improving EOR opportunities.