Securing the Supplies of Fossil Fuels - Energy and Climate: How to Achieve a Successful Energy Transition - page 96

Arctic zone. The exploration of new areas has to be undertaken
carefully, in order to protect the environment. Progress in the area of
offshore production has been spectacular: oil can be produced nowat
water depths reaching or even exceeding 2000m. Further progress is
still expected; it is estimated that 40% of deep offshore reserves still
to be discovered are located between 2000m and 3000m, and 30%
are between 3000m and 4000m water depth. The global volume of
the reserves still to be discovered in the deep offshore and in the
Arctic zone is estimated at around 100Gb [77].
- Putting into production nonconventional oil fields (heavy and extra-
heavy oils). The future potential oil production which might result
from the exploitation of these fields is very significant and the future
impact of these prospects will be presented below.
These different means will be effectively deployed only if the oil price
remains high enough over a long period and if the required investments
are provided, involving the use of the required advanced technologies.
The further delay which might result from the use of these innovative
technologies should help to manage the transition. It should not be used
for postponing the other actions which need to be undertaken. On the
contrary it must be considered as an opportunity for deploying them
actively.
Extra-heavy oils and shales
Extra-heavy oils are formed by deposits at a comparatively shallowdepth,
more or less deeply degraded (oxidation by bacteria), of high specific
gravity and viscosity.
They form either underground layers or tar sands emerging at ground
level. A fraction of these heavy oils can be produced directly, when the oil
reservoir is located deep enough to reach a temperature which makes the
oil fluid enough to circulate in the productionwell as a liquid phase. This is
the case of the heavy oils presently exploited in Venezuela. If it is not the
case, these heavy oils can be exploited by surface mining or by drilling,
using a thermal process to reduce the oil viscosity. The method most often
used is to inject vapour to increase temperature and so reduce viscosity.
Thus, the SAGD (steam assisted gravity drainage) process involves in-
jecting steam in a horizontal well and discharging the heated oil through a
second horizontal well located above the injection well [79]. Such pro-
cesses are already used, and production costs, which can be below20 US $