Page 285 - Fundamentals of Enhanced Oil and Gas Recovery

Enhanced Oil Recovery (EOR) in Shale Oil Reservoirs 273

Figure 9.6 Quality of the oil and gas reservoirs in terms of permeability.

especially near the wellbore. On the other hand, to produce the oil from oil shale,

very high temperature (almost 500 C) should be used. Such a process that the oil
shale has been heated in a low oxygen condition is called retorting. Two techniques
can be applied for heating the rock to extract the oil. The first technique comprises
two step operation including mining the rock and heating the rock at surface. The
second method is to heating the rock at the reservoir. Several oil companies including
ExxonMobil and Shell have developed their technologies for heating the oil shale in
the underground. Their technologies focused on the conversion of Kerogen into liq-
uid oil using electric currents or electric heaters. Such methods are used to produce
the oil from oil shale, on the other hand, horizontal wells with hydraulic fractures are
employed as the main production technology in shale oil reservoirs [1].

9.3 EOR METHODS IN SHALE OIL AND GAS RESERVOIRS
Several enhanced oil recovery (EOR) techniques can be applied in the shale
and tight oil reservoirs; these methods are water injection, gas injection, and surfactant
injection. Following sections described the advantages, and drawbacks of such
methods [1].