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At Heletz, Israel, pilot CO2 injection site two dedicated push-pull experiments have recently been carried out for quantifying the residual trapping in-situ and for comparing the results to values determined from core samples. The target reservoir has a total thickness of about 11m, located at a depth of 1.6 km. The first experiment, carried out in autumn 2016, is mainly based on hydraulic withdrawal tests before and after the creation of the residually trapped zone. In this experiment, the residually trapped zone was also created by fluid withdrawal. In the second test, carried out in summer-autumn 2017, the main characterization method was injection/withdrawal of water and partitioning tracers whose recovery with and without residually trapped CO2 in the formation was compared. In this second experiment the residually trapped zone was created by first injecting CO2 and then injecting water saturated with CO2 to push away the mobile CO2. In this presentation, the resulting estimates for CO2 residual trapping will be presented and the results from the two distinctly different field experiments compared to each other. Further, the respective uncertainties of the two different field testing approaches are discussed. Finally, the in-situ estimates are compared to estimates from laboratory measurements on rock cores, including their modeling with pore-network models. |
