Ikelic - Alliance Digital Repository

OIL SANDS
results In increased pollution hazards for the en
vironment.
First, the bitumens and associated mineralized
waters which are brought to the surface contain
hydrogen sulfide and such other harmful inclu
sions as metals.
Second, bitumens occur close to the surface, at
the lower boundary of fresh ground waters.
Therefore, any
thermal or physical-chemical
stimulation of the producing formation can
directly influence the air, fresh subsurface and
surface waters.
The most explored Tatarstan bitumen deposits in
the sandstones of the Sheshminski horizon occur
at depths of 50-70 meters and 100-130 meters.
They are covered by clay cap rock (argillites)
6-12 meters thick. An overlying water-bearing for
mation of limestone is used for household-utility
purposes in the nearby inhabited areas. Even
under natural conditions,
"traces"
of bitumen
manifest themselves in this water-bearing forma
tion by hydrogen sulfide content, increased
mineralization of water, etc. This is due to poor
isolating properties of the clay cap rocks due to
the presence of tectonic fissures. Therefore,
there are already a number of inhabited areas
that suffer from a deficit of fresh subsurface
waters.
Development experience in the Mordovo-
Karmalskaya deposit of bitumen, using in situ
thermal methods, shows increases in the tem
perature and pressure of the overlying water
bearing formation, changes of chemical composi
tion of the water and a worsening of its quality.
The presence of hydrogen sulfide and mercap-
tans in the air has been observed.
The development of bitumen deposits by under
ground and surface mining methods will require
water drainage and the reclamation of wastes. It
can lead to dewatering of upper water-bearing
layers, and as a result the nearby inhabited areas
will remain without water.
3-22
Due to the shallow depth of burial of the
bitumens, any
certain negative consequences for the environ
method of development can cause
ment. Therefore, say the authors, prior to prepar
projects for the development of bitumen
ing
deposits it is necessary to study
in detail the
hydrogedogic conditions; carry out analyses;
and forecast the ecologic consequences of the
recommended technologies of application.
Conductance of pilot projects should include,
together with the try-out of bitumen recovery
technology, the development of environment
protection methods.
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FOURTEEN IN SITU COMBUSTION
PROJECTS ACTIVE WORLDWIDE
In 1994 there were at least 14 active commercial
In Situ Combustion (ISC) projects worldwide,
says A. Turta of the Petroleum Recovery Institute
in Calgary, Alberta, Canada. More than 160 ISC
pilot projects have been carried out since the
1930s. Turta spoke at last year's Symposium on
Field Applications of In Situ Combustion.
A review of ISC projects was carried out in order
to emphasize the important factors which con
tributed to the success of the processes. Accord
ing to Turta, success in developing an ISC pilot
into a commercial ISC project is strongly con
nected with two factors: 1) starting the operation
from the uppermost part of the structure and ex
tending the process downward and 2) applica
tion of the line drive well configuration instead of
patterns, whenever it is possible. An effective,
peripheral line drive operation requires pool
unitization.
Background
Patented in 1920 in the United States, the first
short-term field pilot took place in the former
Soviet Union in 1933-1934, while the true testing
THE SYNTHETIC FUELS REPORT, JANUARY 1995