The Single Well Chemical Tracer Test (SWCTT) is a precise in-situ method for estimating residual oil saturation (Sor) based on the chromatographic delay between a partitioning tracer (ester) and its hydrolyzed product (alcohol). In this study, laboratory flooding experiments were designed and conducted in a glass-bead packed system at a constant temperature of 149°F to determine the dispersion and kinetic parameters of Ethyl Acetate (EtAc). The experiments were performed under two salinity conditions (5,000 ppm and 50,000 ppm) and simulated using a 1D model in the UTCHEM simulator with a 1 mm cell size. The results demonstrated that salinity significantly influences reaction kinetics and transport properties. Increasing salinity from 5,000 to 50,000 ppm resulted in an increase in the partition coefficient (KD) from 3 to 5.1 and the hydrolysis rate (KH) from 0.1 to 0.5/day. Furthermore, the hydrodynamic dispersion coefficient was determined through matching to be 0.003 ft2/day for the test conducted at a salinity of 5000 ppm and 0.01 ft2/day for the test conducted at a salinity of 50,000 ppm, resulting in accurate agreement between the simulated and experimental data. The Sor values of 0.2414 and 0.2303 obtained from the combined analysis of the model and experimental data showed excellent agreement with the reference value determined by material balance. This consistency serves as robust validation of the laboratory setup and confirms that the developed methodology reliably quantifies both Sor and hydrodynamic dispersion. Crucially, these findings establish a solid foundation for upscaling the methodology to pilot tests and reservoir-scale applications.
Ramezani et al. (Sun,) studied this question.