have been degraded from the original crude oil by bacteria and erosion. Often, bitumen is more viscous than cold molasses and does not flow at ambient conditions. According to World Resources Institute, concentrations of remarkable quantities of heavy oil and oil sands are found in Canada and Venezuela. The U.S. Energy Information Administration (EIA) reported in 2001 that the largest reserves of heavy crude oil in the world were located north of the Orinoco river, 270-mile long by 40-mile wide Orinoco Belt, in eastern Venezuela. At that time Venezuela began authorizing "joint ventures to upgrade the extra-heavy crude resources." Petroleos de Venezuela, S.A. (PDVSA) at that time estimated that there were 270 billion barrels of recoverable reserves in the area, the same amount as the conventional oil reserves of Saudi Arabia. The Orinoco Belt in Venezuela is sometimes described as oil sands, but these deposits are non-bituminous, falling instead into the category of heavy or extra-heavy oil due to their lower viscosity. Natural bitumen and extra-heavy oil differ in the degree by which they have been degraded from the original conventional oils by bacteria. Thirty or more countries are known to have reserves. Production, transportation, and refining of heavy crude oil present special challenges compared to light crude oil. Generally, a diluent is added at regular distances in a pipeline carrying heavy crude to facilitate its flow. Dilbit (diluted bitumen) is a means of transporting highly viscous hydrocarbons. Per the Alberta Oil Sands Bitumen Valuation Methodology, "Dilbit Blends" means "Blends made from heavy crudes and/or bitumens and a diluent usually condensate, for the purpose of meeting pipeline viscosity and density specifications, where the density of the diluent included in the blend is less than 800 kg/m3." Economics Heavy crude oils provide an interesting situation for the economics of petroleum development. The resources of heavy oil in the world are more than twice those of conventional light crude oil. In October 2009, the United States Geological Survey updated the Orinoco deposits (Venezuela) recoverable value to , making this area one of the world's largest recoverable oil deposits. However, recovery rates for heavy oil are often limited from 5-30% of oil in place. The chemical makeup is often the defining variable in recovery rates. New technology utilized for the recovery of heavy oil is constantly increasing recovery rates. On one hand, due to increased refining costs and high sulfur content for some