1. In southern California oil was mined from the early
1860s to the 1890s because the heavy oil would not
flow to the wells.
Tar sands are sandstone reservoirs which have
been filled with oil at shallow depth (less than 2 km—
70-80 ‘C) so that the oil became biodegraded.
Tar sand contains asphaltic oil rich in asphaltenes
and resins. It has a high content of aromatics and
naphthenes compared to paraffins and high content
of nitrogen, sulphur and oxygen.
The viscosity of the biodegraded oil is very high
and the oil must be heated so that the viscosity is
reduced before it can be produced by drilling wells.
Methods of extraction
. Heating of reservoir
— heating can be achieved by soaking the reservoir
with injected steam. This is called cyclic steam
injection.
— bum (make the oil flow or travel, with no
particular purpose or destination) some of the oil in
the subsurface.
— heat the oil electrically, possibly powered by a
nuclear reactor to reduce the CO2 emissions from
burning oil to produce heat.
. Freezing the ground at a distance from the well.
SAGD Steam assisted gravity drainage
. Two horizontal wells are drilled
. Injected steam forms a ‘’steam chamber’’
. Steam and gases rise filling the void left by oil
. The condensed water and crude oil or bitumen is
recovered to the surface by pumps
Unconventional oilHeavy oil and tar sands
AAPG ASUSC . ‫بالبريمة‬ ‫انزل‬ PROSPECT GENERATION . PETROLEUM GEOLOGY SESSION
Thermal Heavy oil recovery methods
CSS Cyclic Steam Stimulation
Stage 1. high pressure steam injected
Stage 2. Major portion of reservoir is thoroughly
saturated
Stage 3. production phase (when production phase
declines another cycle of steam injection begins)
REFERENCES
Photos: stockopedia, sefton resourcess , inc.
Text: Swapnil Pal IMT Geological technology,
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