Residual trapping is one of the key trapping mechanisms for CO2 geological storage, yet difficult to determine in-situ. The present study addressed determination of residual trapping over the entire range of scales from pore to core to field scale, based on data from Heletz, Israel  pilot CO2 injection site. During 2016-2017 two dedicated push-pull experiments have been carried out at the site for the specific purpose of quantifying the residual trapping in-situ, in a well-characterized reservoir layer at 1.6 km depth. The field experiments use a combination of hydraulic, thermal and/or tracer tests before and after creating the residually trapped zone of CO2 and the difference in the responses of these tests is used to estimate the residual trapping of CO2 in-situ. The first experiment is 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, by first injecting CO2, then withdrawing fluids until CO2 was at residual saturation. In the second test, the main characterization method is injection/withdrawal of water and partitioning tracers, whose recovery with and without residually trapped CO2 in the formation is compared. In the second experiment the residually trapped zone is created by first injecting CO2 and then injecting water saturated with CO2 in order to push away the mobile CO2. The experimental field results have been modelled both with simplified analytical models for guidance and with ‘full-physics’ TOUGH2  simulators, to match the observations and to obtain values for in-situ residual trapping. The resulting estimates are discussed as well as compared to results from laboratory measurements on rock cores, including their modeling with pore network models. The pore network modeling has been based on laboratory data on rock samples from the site. In the first set of pore network modeling, data such as throat size distribution, permeability and characteristic two-phase flow functions  were used to calibrate the model, while the second analysis was based on actual scanned pore space data  along with measured hydraulic values.
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 Hingerl, F., Yang, F., Pini, R., Xao, X., Toney, M.F., Liu, Y. and Besnon , S.M. (2016) Characterization of heterogeneity in Heletz sandstone from core to pore scale and quantification of its impact on multiphase flow. International Journal of Greenhouse Gas Control 48 (2016): 69-83.
 Tatomir, A., Matthias Halisch, Duschl, F., Peche, A., Wiegand, B., Schaffer, M., Licha, T., Niemi, A., Bensabat, J., Sauter, M. (2016) An integrated core-based analysis for characterization of flow, transport and mineralogical parameters of the Heletz pilot CO2 storage reservoir. International Journal of Greenhouse Gas Control 48 (2016): 24-43.
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