“…Leakage may occur through fractures, faults or, more generally, caprock weaknesses which may act as preferential ascent routes for deep-seated gases (Ennis-King and Paterson, 2000, Pruess and Garcia, 2002, Rutqvist and Tsang, 2002. Experimental, modelling and field studies evaluating structural integrity of geological carbon repositories have been already conducted (see, among others, Li et al, 2006, Kaszuba et al, 2003, 2005, Gaus et al, 2005, Haszeldine et al, 2005, May, 2005, Marschall et al, 2005, Hildebrand et al, 2004, Pruess and Garcia, 2002, Rutqvist and Tsang, 2002, Ennis-King and Paterson, 2000, Lindeberg, 1997, and references cited therein). From these studies, the following key issues can be identified, which need to be addressed for a quantitative assessment of the sealing efficiency of caprock formations:…”