Extra heavy oil

In a general sense, however, the term heavy oil is often appHed to a petroleum that has a gravity <20° API. The term heavy oil has also been arbitrarily used to describe both the heavy oil that requires thermal stimulation for recovery from the reservoir and the bitumen in bituminous sand (also known as tar sand or oil sand) formations, from which the heavy bituminous material is recovered by a mining operation. Extra heavy oil is the subcategory of petroleum that occurs in the near-soHd state and is incapable of free flow under ambient conditions. The bitumen from tar sand deposits is often classified as an extra heavy oil. 

A process innovation was introduced by Valentine [61], who added an SOx sorbent for mitigating the inhibiting effects of the formed oxysulfides. This process was developed for sulfur removal from extra heavy oils, bitumens, and its emulsions, such as the trade mark Orimulsion. Any active biocatalyst may be used in this process carried out at temperatures close to 50°C. The main features disclosed in patents protecting the use of R. rhodochrous-bas d biocatalysts, in desulfurization reactions are summarized in Table 12. 

The physical and economic or technical approaches made no big difference with respect to the oil that has been produced until now. According to the economic or technical approach - as advancing technology and rising prices will facilitate the economic production of new resources - the boundary will increasingly be shifted from unconventional oil towards conventional oil. This is, for instance, the case in Venezuela and Canada, where extra heavy oil and oil sands have already been economically produced for several years. According to the physical approach, however, this leads to a rise in the production volumes of unconventional oil. In this publication, the distinction between conventional and unconventional occurrences will be made according to the physical approach. 

Includes crude oil, shale oil and NGL, as well as oil sands and extra-heavy oil for Canada and Venezuela, respectively. 

Table 3.2 shows the remaining potential (the sum of reserves and resources) of conventional oil at the end of 2005, which amounts to around 1800 Gb, made up of 1200 Gb reserves and 600 Gb resources. In line with the definition in Section 3.3.1, these figures do not include unconventional oil, such as crude bitumen from oil sands production in Canada or extra heavy oil from Venezuela.11 Almost three-quarters of... 

Heavy cmde oil will not be explicitly addressed, as there are often no clear boundaries with conventional oil and extra-heavy crude oil within a heavy oil reservoir. To avoid double counting, reserves of heavy oil will not be considered either, as they are already partially or completely included in conventional or extra-heavy oil reserves (BGR, 2003). 

Resource estimates and current production According to the USGS, total resources of extra-heavy oil in place worldwide are estimated at around 1350 Gb, of which about 90% are located in the Orinoco Belt in Venezuela. It is estimated that between 240 and 270 Gb of the Venezuelan resources in place are ultimately recoverable. The synthetic crude produced from heavy oil is considered to be refined oil and is, therefore, not subject to OPEC quotas, unlike Venezuela s conventional oil production. 

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. 

The elemental analysis of oil sand bitumen (extra heavy oil) has also been widely reported (Speight, 1990), but the data suffer from the disadvantage that identification of the source is too general (i.e., Athabasca bitumen which covers several deposits) and is often not site specific. In addition, the analysis is quoted for separated bitumen, which may have been obtained by any one of several procedures and may therefore not be representative of the total bitumen on the sand. However, recent efforts have focused on a program to produce sound, reproducible data from samples for which the origin is carefully identified (Wallace et al., 1988). It is to be hoped that this program continues as it will provide a valuable database for tar sand and bitumen characterization. 

With all of the scenarios in place, there is no doubt that petroleum and its relatives residua, heavy oil, and extra heavy oil (bitumen) will be required to produce a considerable proportion of liquid fuels into the foreseeable future. Desulfurization processes will be necessary to remove sulfur in an environmentally acceptable manner to produce environmentally acceptable products. Refining strategies will focus on upgrading the heavy oils and residua and will emphasize the differences between the properties of the heavy crude feedstocks. This will dictate the choice of methods or combinations thereof for conversion of these materials to products (Schuetze and Hofmann, 1984). 

At the present, several countries are recognized as producers of petroleum and have available reserves. These available reserves have been defined (Campbell, 1997), but not quite in the manner outlined above. For example, on a worldwide basis the produced conventional crude oil is estimated to be approximately 784 billion (7 84 X 109) bbl with approximately 900 to 1000 billion (900-1000 X 109) bbl remaining as reserves (Alazard and Montadert, 1993). It is also estimated that there are 180 billion bbl, which remain to be discovered with approximately 1 trillion (1 X 1012) bbl yet-to-be-produced. The annual depletion rate is estimated to be 2.6%. However, it is believed that the apparent increase in the proven reserves of conventional crude oil is due more to revisions of previous estimates of reserves rather than to new discoveries (Alazard and Montadert, 1993). The outlook for liquid fuels into the next century and for the next several decades is believed to hinge upon the availability and conversion of heavy oils, residua, and extra heavy oils (bitumen). 

Table 6-4 Distillation Characteristics for Conventional Crude Oil and Bitumen (Extra Heavy Oil)... 

A dramatic expansion of field upgrading operations in the oil sand bitumen deposits in Canada and the extra-heavy-oil Orinoco deposits in Venezuela. 

The authors have investigated a process to upgrade the bitumen extracted from unconventional extra heavy oils (Oil sands in Canada, Orinoco tar sands in Venezuela, etc.) using nuclear energy. 

The term bitumen (also, on occasion, referred to as native asphalt and extra heavy oil) includes a wide variety of reddish-brown to black materials of semisoUd, viscous to brittle character that can exist in nature with no mineral impurity or with mineral matter contents that exceed 50% by weight. Bitumen is frequently found filling pores and crevices of sandstone, limestone, or argillaceous sediments, in which case the organic and associated mineral matrix is known as rock asphalt. 

Cassani E, Eglinton G. (1986) Organic geochemistry of Venezuelan extra-heavy oils. I. Pyrolysis of asphaltenes a technique for the correlation and maturity evaluation of crude oils. Chem. Geol. 56, 167—83. 

Trabelsi, K., Espitalie, j. Hue, A. Y. 1994. Characterisation of extra heavy oils and tar deposits by modified pyrolysis. In European Symposium on Heavy Oil Technologies in a Wider Europe, Proceedings. 7 and 8 June 1994, 30-40. 

Venezuela is one of the world s largest energy suppliers, in particular, of extraheavy crude oils and bitumens. Continuous steam injection could raise the oil recovery rates. Studies have been conducted in Venezuela to apply a high-temperature gas-cooled reactor to the chemical processes of extracting and upgrading the domestic heavy crude oil resources, of the production of synthetic fuel, and of the gasification of extra heavy oil and the so-called Orimulsion (mixture of bitumens and water) fuel [18]. 

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