Changes

This situation will no doubt change as concern for the potential exhaustion of conventional lighter oil deposits increases; as technology for extracting and upgrading the bitumen contained in the tar sands to an economical feedstock for refineries becomes available; and as new uses for the bitumen are developed, as, for example, the elaboration in Venezuela of the [[Orimulsion]], a direct combustion product, an emulsion composed of 70% extra-heavy oil suspended in 30% water with the help of a chemical surfactant to stabilize the emulsion.<ref name<PachecoandAlonso_1995>Pacheco, L. A., and J. Alonso, 1995, Orimulsion-The growing pain of an idea, ''in'' R. F. Meyer, ed., Heavy crude and tar sands-Fueling for a clean and safe environment: 6th United Nations Institute for Training and Research International Conference on Heavy Crude and Tar Sands (Houston, Texas, February 1995), v. 1, p. 203-211.</ref>

This situation will no doubt change as concern for the potential exhaustion of conventional lighter oil deposits increases; as technology for extracting and upgrading the bitumen contained in the tar sands to an economical feedstock for refineries becomes available; and as new uses for the bitumen are developed, as, for example, the elaboration in Venezuela of the [[Orimulsion]], a direct combustion product, an emulsion composed of 70% extra-heavy oil suspended in 30% water with the help of a chemical surfactant to stabilize the emulsion.<ref name<PachecoandAlonso_1995>Pacheco, L. A., and J. Alonso, 1995, Orimulsion-The growing pain of an idea, ''in'' R. F. Meyer, ed., Heavy crude and tar sands-Fueling for a clean and safe environment: 6th United Nations Institute for Training and Research International Conference on Heavy Crude and Tar Sands (Houston, Texas, February 1995), v. 1, p. 203-211.</ref>

Although problems of upgrading, transportation, and use need to be solved, the economics of producing bitumens and extra-heavy oils are improving, and attention is progressively being focused in the last few years on delineating and assessing the known bitumen and extra-heavy- and heavy-oil deposits and in searching for new ones. Many of the tar-sand deposits [[crop out]] and were identified early in the exploration for oil throughout the world. Most of those that do not crop out are at shallow depths along the rims of [[sedimentary basins]]

Although problems of upgrading, transportation, and use need to be solved, the economics of producing bitumens and extra-heavy oils are improving, and attention is progressively being focused in the last few years on delineating and assessing the known bitumen and extra-heavy- and heavy-oil deposits and in searching for new ones. Many of the tar-sand deposits [https://en.wikipedia.org/wiki/Outcrop crop out] and were identified early in the exploration for oil throughout the world. Most of those that do not crop out are at shallow depths along the rims of [[sedimentary basins]]

and were discovered when drilling for deeper, lighter oil prospects. Not many of those that crop out have remained unknown, but some of those in the shallow subsurface may be still waiting to be discovered.

and were discovered when drilling for deeper, lighter oil prospects. Not many of those that crop out have remained unknown, but some of those in the shallow subsurface may be still waiting to be discovered.

==See also==

==See also==