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The Chemistry and Technology of Petroleum
problems and costs. In situ upgrading could be a very beneficial process for leaving the unwanted
elements in the reservoir and increasing API gravity.
The concept of downhole catalytic upgrading of heavy oil using in situ combustion is not new as
evidenced by interest in the concept and work performed over the past four decades (e.g., Reichert
et al., 1989; Mamora et al., 1993; Weissman and Kessler, 1996; Weissman, 1997; Moore et al.,
1999; Fan and Liu, 2002). The downhole catalytic upgrading process requires suitable placement
of a catalyst bed in the reservoir, the flow of oil through the catalytic bed at a specified temperature
and pressure, and finally drainage of the upgraded oil into the production well.
There are two ways that are currently practiced in bringing heavy crude oil to market. The first
method is to upgrade the material in the oil field and leave much of the material behind as coke, and
then pipeline the upgraded material out as synthetic crude. In this method, the crude is fractionated and the residue is coked. The products of the coking operation, and in some cases some of the
residue, are hydrotreated. The hydrotreated materials are recombined with the fractionated light
materials to form synthetic crude that is then transported to market in a pipeline.
The second method is to effect partial upgrading in situ as part of the recovery process. Such an
option, to produce an acceptable pipeline material would be an ideal solution but has a number of
limitations (Motaghi et al., 2010). For example, the amount of heavy oil production could be limited
by the recovery process and the upgraded products must be compatible with the original or partially
changed heavy oil. The products and the original (partially changed) heavy oil have limited compatibility, which would limit the amount of dilution and again could limit the effectiveness of the
recovery process.
A final option that is already in common practice is to use traditional crude that is located in
the general area to dilute the nontraditional crude to produce an acceptable pipeline material. This
option is workable but does not represent any form of upgrading of the heavy oil—the operative
word is dilution. This option also suffers from the limitation due to the potential for incompatibility.
If the heavy oil and the conventional crude oil have limited compatibility this would limit the
amount of dilution and, consequently, limit the amount of heavy oil recovery. Since this option does
not involve upgrading, it will not be discussed further here.
Thus, it is the purpose of this section to (1) present an outline of the options for surface upgrading facilities and (2) upgrading during an in situ recovery process. Nevertheless, some consideration
of both options is warranted here with the possibility that one or the other (or both) must become a
reality in the not-too-distant future.
7.4.1 PArtIAl uPgrAdIng At tHe surFACe
The influx of heavy oils into the refinery system can offset the shortages of conventional crude
oil but there is also a need for increased refining capacity as well as the need for lighter crude oil
feedstocks. While new residue processing capacity needs be added to existing refineries (Speight,
2007, 2011), there is the need for simple primary upgrading system to make the oil acceptable to a
pipeline—many heavy oils are too viscous to transport by pipeline and fall outside of the specification required by pipeline owners.
The option of partial upgrading at the surface involves recovery of the heavy crude and sufficient upgrading to make the crude transportable by pipeline. As a result of such upgrading, the
properties of the heavy crude would be modified to meet the specification required by the pipeline
company. This could either be through dilution with a suitable (presumably aromatic solvent that
would prevent the asphaltene constituents from separating as a separate phase) or through partial
thermal upgrading.
Traditional heavy feedstock processing such as coking or hydrocracking are very expensive processes, and require large scale to be viable. Thus, adaptation of such processes to the wellhead is not
always viable. Thus, the manner in which refineries convert heavy oil into low-boiling high-value
The Chemistry and Technology of Petroleum
problems and costs. In situ upgrading could be a very beneficial process for leaving the unwanted
elements in the reservoir and increasing API gravity.
The concept of downhole catalytic upgrading of heavy oil using in situ combustion is not new as
evidenced by interest in the concept and work performed over the past four decades (e.g., Reichert
et al., 1989; Mamora et al., 1993; Weissman and Kessler, 1996; Weissman, 1997; Moore et al.,
1999; Fan and Liu, 2002). The downhole catalytic upgrading process requires suitable placement
of a catalyst bed in the reservoir, the flow of oil through the catalytic bed at a specified temperature
and pressure, and finally drainage of the upgraded oil into the production well.
There are two ways that are currently practiced in bringing heavy crude oil to market. The first
method is to upgrade the material in the oil field and leave much of the material behind as coke, and
then pipeline the upgraded material out as synthetic crude. In this method, the crude is fractionated and the residue is coked. The products of the coking operation, and in some cases some of the
residue, are hydrotreated. The hydrotreated materials are recombined with the fractionated light
materials to form synthetic crude that is then transported to market in a pipeline.
The second method is to effect partial upgrading in situ as part of the recovery process. Such an
option, to produce an acceptable pipeline material would be an ideal solution but has a number of
limitations (Motaghi et al., 2010). For example, the amount of heavy oil production could be limited
by the recovery process and the upgraded products must be compatible with the original or partially
changed heavy oil. The products and the original (partially changed) heavy oil have limited compatibility, which would limit the amount of dilution and again could limit the effectiveness of the
recovery process.
A final option that is already in common practice is to use traditional crude that is located in
the general area to dilute the nontraditional crude to produce an acceptable pipeline material. This
option is workable but does not represent any form of upgrading of the heavy oil—the operative
word is dilution. This option also suffers from the limitation due to the potential for incompatibility.
If the heavy oil and the conventional crude oil have limited compatibility this would limit the
amount of dilution and, consequently, limit the amount of heavy oil recovery. Since this option does
not involve upgrading, it will not be discussed further here.
Thus, it is the purpose of this section to (1) present an outline of the options for surface upgrading facilities and (2) upgrading during an in situ recovery process. Nevertheless, some consideration
of both options is warranted here with the possibility that one or the other (or both) must become a
reality in the not-too-distant future.
7.4.1 PArtIAl uPgrAdIng At tHe surFACe
The influx of heavy oils into the refinery system can offset the shortages of conventional crude
oil but there is also a need for increased refining capacity as well as the need for lighter crude oil
feedstocks. While new residue processing capacity needs be added to existing refineries (Speight,
2007, 2011), there is the need for simple primary upgrading system to make the oil acceptable to a
pipeline—many heavy oils are too viscous to transport by pipeline and fall outside of the specification required by pipeline owners.
The option of partial upgrading at the surface involves recovery of the heavy crude and sufficient upgrading to make the crude transportable by pipeline. As a result of such upgrading, the
properties of the heavy crude would be modified to meet the specification required by the pipeline
company. This could either be through dilution with a suitable (presumably aromatic solvent that
would prevent the asphaltene constituents from separating as a separate phase) or through partial
thermal upgrading.
Traditional heavy feedstock processing such as coking or hydrocracking are very expensive processes, and require large scale to be viable. Thus, adaptation of such processes to the wellhead is not
always viable. Thus, the manner in which refineries convert heavy oil into low-boiling high-value