EXPLORATION, RECOVERY, AND TRANSPORTATION 99
incoherent sand or poorly cemented sandstone, large quantities of
sand are produced along with the oil and gas. On its way to the surface, the sand has been known to scour its way completely through
pipes and fittings.
It must also be remembered that in any field where primary
production is followed by a secondary or enhanced production
method, there will be noticeable differences in properties between
the fluids produced (Thomas et al., 1983). The differences in elemental composition may not reflect these differences to any great extent
(Zou et al.., 1989), but more significant differences will be evident
from an inspection of the physical properties. One issue that arises
from the physical property data is that such oils may be outside
the range of acceptability for refining techniques other than thermal options. In addition, overloading of thermal process units will
increase as the proportion of the heavy oil in the refinery feedstock
increases. There is a need for more and more refineries to accept
larger proportions of heavy crude oils as the refinery feedstock and
have the capability to process such materials.
Technologies such as alkaline flooding, microemulsion (micellar/emulsion) flooding, polymer augmented water flooding, and
carbon dioxide miscible/immiscible flooding do not require or
cause any change to the oil. The steaming technologies may cause
some steam distillation that can augment the process when the
steam distilled material moves with the steam front and acts as a
solvent for oil ahead of the steam front (Pratts, 1986). Again, there is
no change to the oil although there may be favorable compositional
changes to the oil insofar as lighter fractions are recovered and
heavier materials remain in the reservoir (Richardson et al, 1992).
The technology where changes do occur involves combustion of
the oil in situ. The concept of any combustion technology requires
that the oil be partially combusted and that thermal decomposition
occur to other parts of the oil. This is sufficient to cause irreversible
chemical and physical changes to the oil to the extent that the product is markedly different to the oil in place. Recognition of this phenomenon is essential before combustion technologies are applied
to oil recovery.
Although this improvement in properties may not appear to
be too drastic, nevertheless it usually is sufficient to have major
advantages for refinery operators. Any incremental increase in the
units of hydrogen/carbon ratio can save amounts of costly hydrogen during upgrading. The same principles are also operative for
incoherent sand or poorly cemented sandstone, large quantities of
sand are produced along with the oil and gas. On its way to the surface, the sand has been known to scour its way completely through
pipes and fittings.
It must also be remembered that in any field where primary
production is followed by a secondary or enhanced production
method, there will be noticeable differences in properties between
the fluids produced (Thomas et al., 1983). The differences in elemental composition may not reflect these differences to any great extent
(Zou et al.., 1989), but more significant differences will be evident
from an inspection of the physical properties. One issue that arises
from the physical property data is that such oils may be outside
the range of acceptability for refining techniques other than thermal options. In addition, overloading of thermal process units will
increase as the proportion of the heavy oil in the refinery feedstock
increases. There is a need for more and more refineries to accept
larger proportions of heavy crude oils as the refinery feedstock and
have the capability to process such materials.
Technologies such as alkaline flooding, microemulsion (micellar/emulsion) flooding, polymer augmented water flooding, and
carbon dioxide miscible/immiscible flooding do not require or
cause any change to the oil. The steaming technologies may cause
some steam distillation that can augment the process when the
steam distilled material moves with the steam front and acts as a
solvent for oil ahead of the steam front (Pratts, 1986). Again, there is
no change to the oil although there may be favorable compositional
changes to the oil insofar as lighter fractions are recovered and
heavier materials remain in the reservoir (Richardson et al, 1992).
The technology where changes do occur involves combustion of
the oil in situ. The concept of any combustion technology requires
that the oil be partially combusted and that thermal decomposition
occur to other parts of the oil. This is sufficient to cause irreversible
chemical and physical changes to the oil to the extent that the product is markedly different to the oil in place. Recognition of this phenomenon is essential before combustion technologies are applied
to oil recovery.
Although this improvement in properties may not appear to
be too drastic, nevertheless it usually is sufficient to have major
advantages for refinery operators. Any incremental increase in the
units of hydrogen/carbon ratio can save amounts of costly hydrogen during upgrading. The same principles are also operative for