Heavy Oil as an Important Resource for the Future With more than 87 million barrels of oil being consumed worldwide every day, oil has come to be the life-blood of modern civilization. It is cheap, relatively easy to procure and use, and has become addictive in terms of its flexibility in enhancing our lives in multiple applications. First and foremost, we are dependent on oil for transportation because more than 90% of transportation energy comes from oil. In addition, oil provides a feedstock for pharmaceuticals, agriculture, plastics, clothing, mining, electricity, and several other products that we use in our everyday lives. Almost all goods are connected to oil in one way or another; we are all dependent on oil and gas more than any other resource, yet not many of us think about this dependence. Oil exploration and production has fueled world economic growth over the last century, and it has reached a stage where the economy of several nations is dependent on the exports of oil to the international market. Global demand for oil is now outstripping supply growth and the importance of this crucial commodity is such that companies engaged in oil exploration and production or transportation have dwarfed those in every other commodities sector. Some important aspects to keep in mind are that oil and gas are absolutely critical to the operation of today's industrial society, essential for sustained economic growth in the industrialized world, and key to progress in nations working their way toward prosperity. This translates into a growing demand for oil and gas, much of it coming from developing nations with low levels of energy use per capita.

Introduction Rocks filled with heavy oil do not comply with established theories for porous media. Heavy oils demonstrate a blend of purely viscous and purely elastic properties, also referred to as viscoelasticity. They have a nonnegligible shear modulus that allows them to support shear-wave propagation depending on frequency and temperature. These oils behave as solids at high frequencies and low temperatures and as fluids at low frequencies and high temperatures. The solid-like properties of heavy oils violate Gassmann’s equation, the most common and widely used fluid-substitution technique in the industry. Few instances of elastic property modeling for heavy-oil-saturated rocks have been reported. Most previously reported work has involved modeling without comparison with measured data, or modeled results on simple grain-fluid aggregates with comparison to measured ultrasonic data. We have modeled the viscoelastic properties of heavy-oil-saturated rock samples using the Hashin—Shtrikman (HS) bounds and the frequency-dependent complex shear modulus of the heavy oil. The two studied rock samples are very different in terms of lithology and consolidation state. In our exercise, we have extended the HS bounds to incorporate complexities such as intragranular porosity and the contribution of heavy oil to rock matrix properties. By considering the complex shear modulus of the heavy oil in our HS calculations, we have been able to estimate attenuation. We also tested the applicability of Ciz and Shapiro’s (2007) form of the generalized Gassmann’s equations in predicting the saturated bulk and shear moduli of the heavy-oil-saturated rock samples.

Introduction Heavy oil has recently become an important resource as conventional oil reservoirs have limited production and oil prices rise. More than 6 trillion barrels of oil in place have been attributed to the world's heaviest hydrocarbons (Curtis et al., 2002). Therefore, heavy-oil reserves account for more than 3 times the amount of combined world reserves of conventional oil and gas. Of particular interest are the large heavy-oil deposits of Canada and Venezuela, which together may account for approximately 55%–65% of the known less than 20° American Petroleum Institute (API) gravity oil deposits in the world (Curtis et al., 2002). Heavy oils cover a large range of API gravities, from 22° for the lightest heavy oils to less than 10° for extra-heavy oils. This wide range of values means that heavy oils vary greatly in their physical properties. Thus, extensive research is required before the properties of heavy oil can be properly understood. Several prevailing issues are seen repeatedly in various fields around the world, including how to make measurements on unconsolidated sandstone cores, production of sand with oil and its effect on formation, exsolution gas drive of heavy oil, understanding the control of viscosity and other physical properties of heavy oils, and monitoring of steam recovery processes. Simply, the high viscosity of heavy oils limits its extraction by traditional methods