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The Chemistry and Technology of Petroleum
a jet slotting process can be used to wash out or drill slots in the oil-saturated zone to increase the
productivity of the individual well. Other shaft configurations include those for mining in weak rock
and shafts for pumping drainage.
Excavation of shafts and tunnels during the mining process results in waste rock that must be
stored or disposed of at the ground surface. The waste rock cannot be dumped in a heap near the
mine shaft as an eyesore for future generations and a source of air and water pollution for untold
years. Air, water, and esthetics must be conserved not only for the present but also against reasonable future contingencies, either natural or man-made.
7.3 NONMINING METHODS
The gravity of tar sand bitumen is usually less than 10°API depending upon the deposit, and viscosity is very high. Whereas conventional crude oils may have a viscosity of several poise (at 40°C,
105°F), the tar sand bitumen has a viscosity of the order of 50,000–1,000,000 cP or more at formation temperatures (approximately 0°C–10°C, 32°F–50°F depending upon the season). This offers a
formidable (but not insurmountable) obstacle to bitumen recovery.
The successful recovery technique that is applied to one deposit/resource is not necessarily the
technique that will guarantee success for another deposit. There are sufficient differences between
the tar sand deposits of the United States and Canada deposits that general applicability is not
guaranteed. Hence, caution is advised when applying the knowledge gained from one resource to
the issues of another resource. Although the principles may at first sight appear to be the same, the
technology must be adaptable.
In principle, the nonmining recovery of bitumen from tar sand deposits is an enhanced recovery
technique and requires the injection of a fluid into the formation through an injection wall. This
leads to the in situ displacement of the bitumen from the recovery and bitumen production at the
surface through an egress (production well). There are, however, several serious constraints that
are particularly important and relate to bulk properties of the tar sand and the bitumen. In fact,
both must be considered in toto in the context of bitumen recovery by nonmining techniques. For
example, such processes need a relatively thick layer of overburden to contain the driver substance
within the formation between injection and production wells.
One of the major deficiencies in applying mining techniques to bitumen recovery from tar sand
deposits is (next to the immediate capital costs) the associated environmental problems. Moreover,
in most of the known deposits, the vast majority of the bitumen lies in formations in which the
overburden/pay zone ratio is too high. Therefore, it is not surprising that over the last two decades
a considerable number of pilot plants have been applied to the recovery of bitumen by nonmining
techniques from tar sand deposits where the local terrain and character of the tar sand may not
always favor a mining option.
In principle, the nonmining recovery of bitumen from tar sand deposits requires the injection of
a fluid into the formation through an injection well, the in situ displacement of the bitumen from the
reservoir, and bitumen production at the surface through an egress (production well). There are, of
course, variants around this theme but the underlying principle remains the same.
There are, however, several serious constraints that are particularly important and relate to bulk
properties of the tar sand and the bitumen. In fact, both must be considered in the context of bitumen
recovery by nonmining techniques. For example, the Canadian deposits are unconsolidated sands
with a porosity ranging up to about 45% whereas other deposits may range from predominantly lowporosity, low-permeability consolidated sand to, in a few instances, unconsolidated sands. In addition, the bitumen properties are not conducive to fluid flow under deposit conditions. Nevertheless,
where the general nature of the deposits prohibits the application of a mining technique, a nonmining method may be the only feasible bitumen recovery option.
Another general constraint to bitumen recovery by nonmining methods is the relatively low
injectivity of tar sand formations. Thus it is usually necessary to inject displacement or recovery
The Chemistry and Technology of Petroleum
a jet slotting process can be used to wash out or drill slots in the oil-saturated zone to increase the
productivity of the individual well. Other shaft configurations include those for mining in weak rock
and shafts for pumping drainage.
Excavation of shafts and tunnels during the mining process results in waste rock that must be
stored or disposed of at the ground surface. The waste rock cannot be dumped in a heap near the
mine shaft as an eyesore for future generations and a source of air and water pollution for untold
years. Air, water, and esthetics must be conserved not only for the present but also against reasonable future contingencies, either natural or man-made.
7.3 NONMINING METHODS
The gravity of tar sand bitumen is usually less than 10°API depending upon the deposit, and viscosity is very high. Whereas conventional crude oils may have a viscosity of several poise (at 40°C,
105°F), the tar sand bitumen has a viscosity of the order of 50,000–1,000,000 cP or more at formation temperatures (approximately 0°C–10°C, 32°F–50°F depending upon the season). This offers a
formidable (but not insurmountable) obstacle to bitumen recovery.
The successful recovery technique that is applied to one deposit/resource is not necessarily the
technique that will guarantee success for another deposit. There are sufficient differences between
the tar sand deposits of the United States and Canada deposits that general applicability is not
guaranteed. Hence, caution is advised when applying the knowledge gained from one resource to
the issues of another resource. Although the principles may at first sight appear to be the same, the
technology must be adaptable.
In principle, the nonmining recovery of bitumen from tar sand deposits is an enhanced recovery
technique and requires the injection of a fluid into the formation through an injection wall. This
leads to the in situ displacement of the bitumen from the recovery and bitumen production at the
surface through an egress (production well). There are, however, several serious constraints that
are particularly important and relate to bulk properties of the tar sand and the bitumen. In fact,
both must be considered in toto in the context of bitumen recovery by nonmining techniques. For
example, such processes need a relatively thick layer of overburden to contain the driver substance
within the formation between injection and production wells.
One of the major deficiencies in applying mining techniques to bitumen recovery from tar sand
deposits is (next to the immediate capital costs) the associated environmental problems. Moreover,
in most of the known deposits, the vast majority of the bitumen lies in formations in which the
overburden/pay zone ratio is too high. Therefore, it is not surprising that over the last two decades
a considerable number of pilot plants have been applied to the recovery of bitumen by nonmining
techniques from tar sand deposits where the local terrain and character of the tar sand may not
always favor a mining option.
In principle, the nonmining recovery of bitumen from tar sand deposits requires the injection of
a fluid into the formation through an injection well, the in situ displacement of the bitumen from the
reservoir, and bitumen production at the surface through an egress (production well). There are, of
course, variants around this theme but the underlying principle remains the same.
There are, however, several serious constraints that are particularly important and relate to bulk
properties of the tar sand and the bitumen. In fact, both must be considered in the context of bitumen
recovery by nonmining techniques. For example, the Canadian deposits are unconsolidated sands
with a porosity ranging up to about 45% whereas other deposits may range from predominantly lowporosity, low-permeability consolidated sand to, in a few instances, unconsolidated sands. In addition, the bitumen properties are not conducive to fluid flow under deposit conditions. Nevertheless,
where the general nature of the deposits prohibits the application of a mining technique, a nonmining method may be the only feasible bitumen recovery option.
Another general constraint to bitumen recovery by nonmining methods is the relatively low
injectivity of tar sand formations. Thus it is usually necessary to inject displacement or recovery