Environmental Engineering Reference
In-Depth Information
Exploration for Unconventional
Hydrocarbons: Shale Gas and Shale Oil
IAIN C. SCOTCHMAN
ABSTRACT
Over the last 25 years the development of unconventional hydro-
carbons, shale gas and shale oil, has come to dominate the oil industry,
particularly in the USA where their development has dramatically
overturned the decline in domestic production, with self-suciency in
gas production attained. Exploration for and production of shale-based
resources requires a very different approach and mind-set from that
required for conventional resource exploration and production. The
aim of this chapter is to discuss the geology of shale resources and the
techniques developed for their exploration and exploitation.
1 Introduction
Unconventional hydrocarbons comprise oil and gas resources trapped in
any ''non-conventional'' reservoir (i.e. not the porous and permeable sand-
stones and limestones which comprise ''conventional'' reservoirs), ranging
from gas hydrates and oil shales located beneath the sea-bed or ground
surface, respectively, through shale gas and shale oil to coal-bed methane
(CBM) (see Figure 1). However, in general, the term ''unconventional
hydrocarbons'' has come to relate to shale resources and CBM, as gas hy-
drate development is very much in its infancy and oil shale, which cradled
the 19
th
century UK petroleum industry in central Scotland, requires
considerable energy input to retort the shales, with consequent large
