Modelling and Design of Field Tests for Characterization and Monitoring of CO2 Injected to a Deep Saline Aquifer at the Heletz Site

Field testing is essential for the advancement of geological CO2 storage technology, both to further our understanding of the processes and fate of injected CO2, and to build public acceptance by demonstration of CO2 storage and monitoring. At the Heletz site in Israel, a small-scale field experiment is being designed to study CO2 transport and trapping processes, as part of the EU-FP7 MUSTANG project. Modelling of the flow and transport of CO2, brine, heat and tracers is used to evaluate design options with the aim to facilitate the monitoring and characterization of injected CO2 and maximize the information gained from the field tests. In this study a dipole test configuration is investigated with the aim to study migration of fluids and in-situ trapping mechanisms under influence of geological heterogeneity between two boreholes. The modelling evaluates how hydraulic and tracer tests can be used to study and quantify these processes and how different design options affect the outcome of the field tests. The sensitivity of hydraulic and tracer signals measured at the bore holes to parameters affecting CO2 migration and trapping in the formation was investigated for different design options. It was found that the both the pressure signal and tracer breakthrough curves are affected by two-phase flow effects in relative permeability and capillary pressure. Geological heterogeneity affects the measured signals and combination of different measurements can reduce uncertainty.