ABSTRACT
The term unconventional refers to the use of recent technological innovations to extract oil and natural gas from formerly inaccessible geological formations. For the first century of oil and gas production, extraction entailed drilling a well vertically into the ground and pumping petroleum to the surface. The permeability and porosity of targeted sedimentary rock determined how much of the desired substance appeared (oil and gas flow relatively easily through sandstone, for example, but are more tightly trapped in shale). As easily extractable supplies began to wane, drillers experimented with new strategies. Eventually, unconventional techniques made production possible where oil and gas had previously been out of reach. Two distinct types of unconventional extraction are addressed in this chapter.
