Design and Analysis of Field Experiments for the Investigation of In-Situ CO2 Trapping

At Heletz, Israel, a series of field experiments, including injection of supercritical (sc) CO2 to a deep saline aquifer, are scheduled to begin 2011, as part of the EU-FP7 MUSTANG project. The aim is to investigate processes governing the fate of geologically stored CO2, including residual trapping and dissolution to formation brine. Field studies are of key importance for assessment of the relative importance of these processes. Test configurations for scCO2 and brine injections/withdrawals include a single-well push-pull test as well as a dipole test allowing control of the flow field and measurements between the two wells. Measurement techniques to be employed both before and after CO2 injection include hydraulic testing, standard tracers as well as novel partitioning tracers, and thermal conductivity. Detailed numerical modeling of the tests is critical for a successful design of the field program, the interpretation of the measurements and assessment of parameters affecting the trapping mechanisms. To this end, a suite of numerical models of increasing complexity have been built to address the different field experiment configurations and measurement techniques that will be employed on site. This study presents the results of these modeling studies aimed at optimizing the design of the field testing and relating the various measurements to the in-situ CO2 trapping characteristics of the storage formation. The sensitivity of formation parameters to the residual trapping and dissolution of scCO2 are investigated and effects of formation layering and heterogeneity are assessed.