Successful Low Salinity Single-Well Pilot and SWCTT Operations in a High Temperature/High Salinity Carbonate Reservoir of the UAE. SWCTT Operations, Numerical Interpretation, and Integration with Well Logging

Abstract This paper provides results and interpretation of an onshore Middle-East field first low salinity EOR pilot, carried out to verify the previous lab results of an extensive project to evaluate the EOR potential of low salinity water injection. It presents the design, execution and results of the extensive SWCTT project preparation of two Single Well Chemical Tracer Tests (SWCTT) and a detailed saturation logging campaign designed to evaluate the EOR potential of low salinity water injection. Following an extensive laboratory program of fluid-fluid tests and core flood experiments. Single Well Chemical Tracer Tests (SWCTT) were designed based on the results of this experimental program. The SWCTT pilot was accompanied by a detailed saturation logging campaign to evaluate changes in remaining oil saturations (ROS) in a fractured carbonate reservoir in south-east Abu Dhabi. The SWCTT pilot, together with PLT, noise-temperature logs and Pulsed Neutron Capture (PNC) logs provided insight into ROS distribution across the reservoir intervals. Contributions from the different reservoir intervals contacted by the tracer were included, aligned with log results, and uncertainties in ROS determination were calculated. This paper will focus on the specially designed multi-realization numerical simulations considered by field operator as the most robust method for pilot results. Detailed radial single-well models were built with fine geological layering, and partitioning and hydrolysis reactions were added to match historical tracer back-production profiles. From the history match of tracer profiles non-ideal flows were detected impacting the tracer's profile response and contribute to SWCTT uncertainties. The results confirm a positive low salinity EOR effect, matching the results from the laboratory experiments, with δROS above 4% and the EOR potential of low salinity water on this reservoir. This paper presents the field operator's first successful Low Salinity EOR pilot at HT/HS conditions. It highlights the ability of pilot result interpretation using multi-realization simulation models and demonstrates the importance of a thorough logging campaign to support and validate SWCTT modelling work.