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Recovery of Heavy Oil and Tar Sand Bitumen
may be achieved in fractured reservoirs by improving mining methods than in less heterogeneous
reservoirs. Other reservoirs that are good candidates for oil mining are those that are shallow have
high oil saturation, have a nearby formation that is competent enough to support the mine, and cannot be efficiently produced by conventional methods.
Surface mining is the mining method that is currently being used by Suncor Energy and Syncrude
Canada Limited to recover oil sand from the ground. Surface mining can be used in mineable oil
sand areas, which lie under 75 m (250 ft) or less of overburden material. Only 7% of the Athabasca
Oil Sands deposit can be mined using the surface mining technique, as the other 93% of the deposit
has more than 75 m of overburden. This other 93% will have to be mined using different mining
techniques.
The first step in surface mining is the removal of muskeg and overburden. Muskeg is a watersoaked area of decaying plant material that is 1–3 m thick and lies on top of the overburden material.
Before the muskeg can be removed it must be drained of its water content. The process can take
up to 3 years to complete. Once the muskeg has been drained and removed, the overburden must
also be removed. Overburden is a layer of clay, sand, and silt that lies directly above the oil sands
deposit. Overburden is used to build dams and dykes around the mine and will eventually be used
for land reclamation projects. When all of the overburden is removed, the oil sand is exposed and
is ready to be mined.
There are two methods of mining currently in use in the Athabasca Oil Sands. Suncor Energy
uses only the truck and shovel method of mining whereas Syncrude uses the truck and shovel
method of mining as well as draglines and bucket-wheel reclaimers. These enormous draglines
and bucket-wheels are being phased out and soon will be completely replaced with large trucks
and shovels. The shovel scoops up the oil sand and dumps it into a heavy hauler truck. The
heavy hauler truck takes the oil sand to a conveyor belt that transports the oil sand from the
mine to the extraction plant. Presently, there are extensive conveyor belt systems that transport
the mined oil sand from the recovery site to the extraction plant. With the development of new
technologies these conveyors are being phased out and replaced with hydrotransport technology.
Hydrotransport is a combination of ore transport and preliminary extraction. After the bituminous sands have been recovered using the truck and shovel method, it is mixed with water and
caustic soda to form a slurry and is pumped along a pipeline to the extraction plant. The extraction process thus begins with the mixing of the water and agitation needed to initiate bitumen
separation from the sand and clay.
Mine spoils need to be disposed of in a manner that assures physical stabilization. This means
appropriate slope stability for the pile against not only gravity, but also earthquake forces. Since
return of the spoils to the mine excavations is seldom economical, the spoil pile must be designed
as a permanent structure whose outline blends into the landscape. Straight, even lines in the pile
must be avoided.
Even though estimates of the recoverable oil from the Athabasca deposits are only of the order
of 27 × 109 bbl of synthetic crude oil (representing <10% of the total in-place material), this is,
for the Canadian scenario, approximately six times the estimated volume of recoverable conventional crude oil. In addition, the comparative infancy of the development of the alternative options
almost ensured the adoption of the mining option for the first two (and even later) commercial
ventures.
Underground mining options have also been proposed but for the moment have not been developed because of the fear of collapse of the formation onto any operation/equipment. This particular
option should not, however, be rejected out-of-hand because a novel aspect or the requirements of
the developer (which remove the accompanying dangers) may make such an option acceptable.
Currently, bitumen is recovered commercially from tar and deposits by a mining technique. This
produces tar sand that is sent to the processing plant for separation of the bitumen from the sand
prior to upgrading.
Recovery of Heavy Oil and Tar Sand Bitumen
may be achieved in fractured reservoirs by improving mining methods than in less heterogeneous
reservoirs. Other reservoirs that are good candidates for oil mining are those that are shallow have
high oil saturation, have a nearby formation that is competent enough to support the mine, and cannot be efficiently produced by conventional methods.
Surface mining is the mining method that is currently being used by Suncor Energy and Syncrude
Canada Limited to recover oil sand from the ground. Surface mining can be used in mineable oil
sand areas, which lie under 75 m (250 ft) or less of overburden material. Only 7% of the Athabasca
Oil Sands deposit can be mined using the surface mining technique, as the other 93% of the deposit
has more than 75 m of overburden. This other 93% will have to be mined using different mining
techniques.
The first step in surface mining is the removal of muskeg and overburden. Muskeg is a watersoaked area of decaying plant material that is 1–3 m thick and lies on top of the overburden material.
Before the muskeg can be removed it must be drained of its water content. The process can take
up to 3 years to complete. Once the muskeg has been drained and removed, the overburden must
also be removed. Overburden is a layer of clay, sand, and silt that lies directly above the oil sands
deposit. Overburden is used to build dams and dykes around the mine and will eventually be used
for land reclamation projects. When all of the overburden is removed, the oil sand is exposed and
is ready to be mined.
There are two methods of mining currently in use in the Athabasca Oil Sands. Suncor Energy
uses only the truck and shovel method of mining whereas Syncrude uses the truck and shovel
method of mining as well as draglines and bucket-wheel reclaimers. These enormous draglines
and bucket-wheels are being phased out and soon will be completely replaced with large trucks
and shovels. The shovel scoops up the oil sand and dumps it into a heavy hauler truck. The
heavy hauler truck takes the oil sand to a conveyor belt that transports the oil sand from the
mine to the extraction plant. Presently, there are extensive conveyor belt systems that transport
the mined oil sand from the recovery site to the extraction plant. With the development of new
technologies these conveyors are being phased out and replaced with hydrotransport technology.
Hydrotransport is a combination of ore transport and preliminary extraction. After the bituminous sands have been recovered using the truck and shovel method, it is mixed with water and
caustic soda to form a slurry and is pumped along a pipeline to the extraction plant. The extraction process thus begins with the mixing of the water and agitation needed to initiate bitumen
separation from the sand and clay.
Mine spoils need to be disposed of in a manner that assures physical stabilization. This means
appropriate slope stability for the pile against not only gravity, but also earthquake forces. Since
return of the spoils to the mine excavations is seldom economical, the spoil pile must be designed
as a permanent structure whose outline blends into the landscape. Straight, even lines in the pile
must be avoided.
Even though estimates of the recoverable oil from the Athabasca deposits are only of the order
of 27 × 109 bbl of synthetic crude oil (representing <10% of the total in-place material), this is,
for the Canadian scenario, approximately six times the estimated volume of recoverable conventional crude oil. In addition, the comparative infancy of the development of the alternative options
almost ensured the adoption of the mining option for the first two (and even later) commercial
ventures.
Underground mining options have also been proposed but for the moment have not been developed because of the fear of collapse of the formation onto any operation/equipment. This particular
option should not, however, be rejected out-of-hand because a novel aspect or the requirements of
the developer (which remove the accompanying dangers) may make such an option acceptable.
Currently, bitumen is recovered commercially from tar and deposits by a mining technique. This
produces tar sand that is sent to the processing plant for separation of the bitumen from the sand
prior to upgrading.