ABSTRACT
The extraction of shale gas from formations with lower permeabilities compared to other rock formations has became economical with the emergence of relatively newer technologies such as hydraulic fracturing (commonly known as "tracking") and precision drilling of wells (Arthur et al., 2008). The extraction of shale gas using hydraulic fracturing has increased estimates of natural gas resources enormously in many countries (Table 7.1), with an overall worldwide increase from 18 to 118 trillion cubic meters (Tcm) (Howarth et al., 2011).
