Natural bitumen and extra-heavy oil

Publisher Summary Extra-heavy oil and natural bitumen represent crude oils which have been severely degraded by microbial action, as evidenced by their paucity of low-molecular-weight saturated hydrocarbons. The chemical and physical attributes of extra-heavy oil lead to an array of problems with respect to exploitation, transportation, storage, and refining. This is reflected in the increased cost of extraction and processing and physical limitations on production capacity. Due to the high viscosity of the crude, some form of improved recovery is usually required for production. Two fundamental upgrading processes are presently employed to prepare heavy oil and natural bitumen for transportation and refining to finished products. These processes are carbon rejection and hydrogen addition. Each process improves the hydrogen-to-carbon ratio but by following different paths. New technologies allow production rates comparable to those of conventional oil reservoirs. Major cost-reduction breakthroughs in upgrading, transportation, and refining are enhancing the movement of these hydrocarbons into mainstream world oil supply.