Tar Sand Bitumen

Coal, tar, and heavy oil fuel reserves are widely distributed throughout the world. In the Western hemisphere, Canada has large tar sand, bitumen (very heavy cmde oil), and coal deposits. The United States has very large reserves of coal and shale. Coal comprises ca 85% of the U.S. recoverable fossil energy reserves (6). Venezuela has an enormous bitumen deposit and Brazil has significant oil shale (qv) reserves. Coal is also found in Brazil, Colombia, Mexico, and Pern. Worldwide, the total resource base of these reserves is immense and may constitute >90% of the hydrocarbon resources in place (see... 

Distinctions between tar sands bitumens and heavy oils are based largely on differences in viscosities. The bitumen in oil sand has a specific gravity of less than 0.986 g/mL (12°API), and thus oil sands may be regarded as a source of extremely heavy cmde oil. Whereas heavy oils might be produced by the same techniques used for the lighter cmde oils, the bitumens in tar sands are too viscous for these techniques. Consequently these oil-bearing stones have to be mined and specially processed to recover contained hydrocarbon. 

Physical methods of fractionation of tar sand bitumen usually indicate high proportions of nonvolatile asphaltenes and resins, even in amounts up to 50% wt/wt (or higher) of the bitumen. In addition, the presence of ash-forming metallic constituents, including such organometaUic compounds as those of vanadium and nickel, is also a distinguishing feature of bitumen. 

The API gravity of tar sand bitumen varies from 5 to ca 10°API, depending on the deposit, and the viscosity is very high. Whereas conventional cmde oils may have a high (>100 MPa-s(=cP)) viscosity at 40°C, tar sand bitumen has a viscosity on the order of 10-100 kPa-s(10 -10 P) at formation temperature (ca 0—10°C), depending on the season. This offers a formidable obstacle to bitumen recovery and, as a result of the high viscosity, bitumen is relatively nonvolatile under conditions of standard distillation (Table 4) (12,13), which influences choice of the upgrading process. 

For many years, petroleum and heavy oil were very generally defined in terms of physical properties. For example, heavy oil was considered to be a crude oil that had gravity between 10 and 20° API. For example. Cold Lake heavy crude oil (Alberta, Canada) has an API gravity equal to 12°, but extra-heavy oil (such as tar sand bitumen), which requires recovery by nonconventional and nonenhanced methods, has an API gravity in the range 5 to 10°. Residua would vary depending on the temperature at which distillation was terminated, but vacuum residua were usually in the range 2 to 8° API. 

A. Zandona, 0. J. Busch, L. E. Hettinger, W. P., Jr. "Reduced Crude Conversion Symposium on Production, Characterization and Processing of Heavy Oils, Tar Sand Bitumens, Shale Oils and Coal-Derived Liquids", University of Utah, 1981. 

Canadian oil sand processing plants have been developed by Syncrude and Suncor for extraction and upgrading of tar sand bitumen into fuel. Aboveground surface mining and in-situ methods have been developed to recover raw material. Bitumen recovery from surface mined oil sand requires conditioning in order to free the bitumen from the sand matrix. 

Protolysis can involve not only C—H but also C—C bonds [Eq. (1.23)] this explains why alkanes can be directly cleaved protolytically by superacids, which is of significance, for example, in hydrocleaving heavy oils, shale oil, tar-sand bitumens, and even coals ... 

Analytical separation and spectroscopic techniques normally used for petroleum crudes and residues were modified and used to characterize coal liquids, tar sands bitumens, and shale oils. These techniques include solvent extraction, adsorption, ion-exchange, and metal complexing chromatography to provide discrete fractions. The fractions are characterized by various physical and spectroscopic methods such as GLC, MS, NMR, etc. The methods are relatively fast, require only a few grams of sample, provide compound type fractions for detailed characterization, and provide comparative compositional profiles for natural and synthetic fuels. Additional analytical methods are needed in some areas. 

The literature on tar sands and tar sand bitumen is not very rich as compared with that on shale oils and coal. Most of the currently available... 

Table III. Chemical Analysis and Molecular Weights of Tar Sands Bitumen, Coal Liquids, and Their Fractions...

Tar Sand Bitumen. This material is very viscous, black, and contains a considerable amount of sulfur, some nitrogen and oxygen, and no... 

Figure 2. GLC of saturates from tar sands bitumen. Numbers indicate n-poraffin standards.

Figure 3. IH NMR spectra of aromatic fractions from tar sands bitumen...

Of the material boiling above 470°F, the tar sand bitumen contains more saturates than the other fuels. As pointed out above, these saturates are unique in that they do not contain free alkanes while the saturates from the other fuels contain 22-40% alkanes as determined by MS (Table VI). 

Perhaps, where these fuels differ most is in the amount of resins, asphaltenes, and benzene insolubles. The shale oils contain a very large amount of resins from 12 to 69%, or approximately 50% by weight on a total shale oil basis. The tar sand bitumen contains only half as much resins, and the coal liquids contain much less. On the other hand, the asphaltenes are significant in the tar sand bitumen and in the Pitt Seam coal liquids. These latter materials are the only ones to contain a significant amount of benzene insolubles. 

The authors wish to thank A. V. Vayda for aid in preparing the coal liquids W. E. Magison for help in obtaining the NMR data W. Hubis and H. P. Malone for helpful discussions The Oil Shale Corp. and Sun Oil Co. for providing the samples of shale oil and tar sand bitumen, respectively, and for their permission to publish the data obtained on them. 

Another major difference between the tar sand bitumen and the petroleum residues is suggested in Table IV. In all the petroleum samples, the base content is higher than the acid content. In the P. R. Spring sample, the acids are higher than the bases. This could indicate the differences in oxidation, maturation, or origin for the tar sand bitumen as compared with crude oils. In addition, the acid content may often have important effects on recovery processes, such as those which rely on caustic flooding. 

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