Abstract
Saline aquifers in deep sedimentary formations are considered the primary candidates for geological storage of CO2, due to their large volumetric capacity that would be sufficient to meet the needs for CCS storage space in a global scale. In comparison to depleted oil and gas reservoirs the deep saline aquifers are, however, less investigated as there has previously been little economic interest in them. Effective methods for characterizing the storage aquifers are crucial for a successful implementation of any CCS project and therefore being developed and transferred from other applications in a various CCS projects.The objective of EU FP7 funded project MUSTANG project (A multiple space and time scale approach for the quantification of deep saline formations for CO2 storage, www.co2mustang.eu) has been to develop methods for characterizing saline aquifers and for understanding their properties. An essential part of this was establishment of a CO2 injection site at Heletz, Israel, where small-scale scientifically motivated injection experiments are planned to be carried out in presently ongoing continuation projects TRUST (http://trust-co2.org/) and CO2QUEST (www.co2quest.eu).While a large number of publications has been already produced based on the work in the MUSTANG project and its successors, and published in different journals, including this one, the objective of this Special Edition has been to gather some of the concluding work in the same journal issue. The focus has in particular been in summarizing the site characterization work carried out at the Heletz site, thereby providing readers an easy overview of the findings and characteristics of the site. In addition, some related work from some of the other sites investigated in MUSTANG project is also included, namely work from the sites Hontomin, Maguelone and a natural analog site in the North Sea. The results are intended to add to our understanding on relevant properties of geological formations as candidates for CO2 geological storage.