Ikelic - Alliance Digital Repository

OIL SANDS
Chakrabarty and Longo present laboratory and
field data that support the hypothesis that the
minerals in the ciasts play a role in the produc
tion problems of the shaley oil sands. Laboratory
tests reveal that ciasts in the shaley oil sands
have an abundance of carbonate minerals such
as sWerite (iron carbonate) and aluminosilicate
minerals such as kaolinite and feldspar.
Laboratory
studies under steam stimulation con
ditions show that the mineral reactions between
carbonates and aluminosilicates can generate for
mation damaging products such as swelling clay
and carbon dioxide.
Swelling clay can damage the formation by plug
ging the pore throats, whereas carbon dioxide
can lead to near-well-bore scaling. Calcium car
bonate scales have been observed in downhole
pumps and liners in Cold Lake wells. The field
bitumen production appears to be inversely corre
lated with the carbonate content of the ciasts.
The field bitumen production is also inversely
correlated with the amount of carbon dioxide gen
erated in the laboratory by
tions of ciasts.
Chakrabarty
hydrothermal reac
and Longo conclude that the
bitumen production potential of a well can be pre
dicted from the carbonate content of the ciasts
and the amount of CO, generated in the
laboratory by
mineral reactions. The higher the
carbonate content and the higher the C02 gener
ated, the lower is the bitumen production poten
tial.
Possible remediation methods for the production
problems in the complex reservoir include HCI
and EDTA to dissolve calcite scales, and mud
acid to dissolve clays and silica.
Possible prevention methods for the production
problems in the complex reservoir include 1)
avoidance of the potentially troublesome part of
priori"
the complex reservoir by "a assessment of
the reservoir quality, and 2) changes in the
operating conditions of the cyclic steam stimula
tion process.
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3-18
INTERNATIONAL
INTEREST BUILDING IN CHINA'S TAR SANDS
In China, tar sands deposits have been found in
Xinjiang Autonomous Region, in Inner Mongolia
Autonomous Region, and in Qinghai and Sichuan
Provinces. However, only a little work on the
geological exploration of tar sands has been
carried out to date.
Zhun GeEr Basin in Xinjiang Autonomous
Region
Tar sands are widely distributed in the
northwestern part of the Zhun GeEr Basin of Xin
jiang
Examples include Hong San Zui District,
Karamay-Hei You San District, Bei Jian Tan Dis
Autonomous Region in northwestern China.
trict, and Wu Er He District. Only preliminary in
vestigations have been completed.
Tar sands in the Hong San Zui District belong
geologically to the Cretaceous Period; in
Karamay-Hei You San they belong to the Triassic
and lower Jurassic Periods; in Bei Jian Tan they
belong to the Jurassic and Cretaceous Periods;
and in Wu Er He District they belong to the
Cretaceous Period.
Hong San Zui tar sands have been found in an
area of about 70 square kilometers, with an effec
tive thickness of about 6 meters, near the ground
surface. The porosity of the deposit is
28 percent, the bitumen content is about
7.7 percent, and geological reserves are es
timated at 20 x 106
tons of bitumen.
Karamay-Hei You San tar sands have been found
over an area of about 45 square kilometers, with
an effective thickness of about 8 meters, near the
ground surface. The porosity of the deposit is
25 percent, the bitumen content is about
8.3 percent, and geological reserves are believed
to be 25 x 106
tons of bitumen.
Bei Jian Tan tar sands have been found over an
area of 40 square kilometers, with a thickness of
THE SYNTHETIC FUELS REPORT, JANUARY 1995