Abstract
<jats:title>Abstract</jats:title> <jats:p>Mature oil fields have become a strategic focus for research aimed at increasing hydrocarbon production and associated reserves, particularly in countries where national economies are heavily reliant on oil and gas activities. The Yariguí-Cantagallo field, located in Colombia's Middle Magdalena Valley Basin (MMVB), was discovered in 1953 and has been undergoing water injection since 2010. However, the effectiveness of this process has been limited by reservoir heterogeneity, which promotes the development of preferential flow paths and leaves significant volumes of residual mobile oil unswept. This study presents the design, implementation, and results of Colombia's first polymeric surfactant (PS) One-Spot Pilot (OSP) aimed at enhancing oil recovery in mature reservoirs.</jats:p> <jats:p>Laboratory tests included rheological and interfacial tension (IFT) measurements, which were complemented by core flooding experiments to design the polymeric surfactant formulation (PS4M) and validate its displacement efficiency. In the field, the water was collected and filtered from a nearby injector well. The PS4M solution was dosed from intermediate bulk container (IBC´s) into the filtered brine flowline which was injected into the producer well using a high-pressure pump. Residual oil saturation (Sor) was monitored using time-lapse Pulsed-Neutron Logging (PNL) in Carbon/Oxygen (C/O) mode.</jats:p> <jats:p>Field results showed a cumulative reduction in oil saturation between 10% and 14% in the target sand, with an incremental 6% reduction attributable to the polymeric surfactant injection beyond waterflooding effects, validating the effectiveness of PS4M injection in mobilizing residual oil. In addition, as well pressure increased, confirming the mobility control during the PS4M slug injection. Oil production was restored without any loss of productivity or strong emulsions. The good correlation between field and laboratory data confirmed both the reliability of the selected chemical formulation and the robustness of PNL C/O logs as a monitoring tool.</jats:p> <jats:p>Polymeric Surfactant was proved as an alternative for chemical EOR projects. This pilot marks a milestone in Colombia's chemical EOR roadmap and it was applied in shorter time than conventional pilots, providing property-level information for future applications in similar mature fields nationwide.</jats:p>