5/16/2023 0 Comments Viscosity equationTypically, in the hot solvent process such as steam/light solvents co-injection in SAGD (see Fig. Essentially, these processes offered many advantages including improved production rate, in situ upgrading of the bitumen, lower steam requirement, reduced consumption of natural gas as well as reduction in the emission of greenhouse gasses (Nourozieh et al. (Butler and Mokrys 1992 Etherington and McDonald 2004 Motahhari et al. These include non-thermal solvent-based method such as the vapor extraction process (VAPEX), and the thermal-assisted methods including hot VAPEX method (N-Solv), expanding solvent SAGD (ES-SAGD), steam and gas push (SAGP), steam alternating solvent process (SAS) and liquid addition to steam (LASER), etc. Thus, several solvent-based processes and the hybrid ones have been proposed. Similarly, co-injection of non-condensable gas, as solvent, with steam causes thermal insulation effect at the top of steam chamber, which subsequently reduces the heat loss during a steam-based system such as SAGD (Azinfar et al. Steam and solvent injection into a bitumen reservoir reduces the viscosity (through solvent dissolution and asphaltene precipitation) and improves the recovery (Imai et al. Better still, injection of steam along with solvent, or combination of both, is an efficient method to extract bitumen. Essentially, addition of diluents and organic solvents with bitumen leads to significant viscosity reduction (Shu 1984 Mehrotra 1990 Miadonye et al. Solvent-assisted methods have been introduced in bitumen recovery and production to serve as alternatives to the thermal recovery methods, which have various disadvantages including high energy, and water consumption, water pollution and emission of greenhouse gas (Azinfar et al. However, because of high viscosity, bitumen recovery, production, transportation, and refining are characterized with several technical challenges including high-energy consumption during recovery, high-pressure drop during flow and transportation, and high energy required for pumping (Alade et al. The total reserves of bitumen and extra-heavy oil in Canada, Venezuela, USA, China, and Nigeria are comparable to that of light crude oil, especially in Middle East, USA, and Russia (Clark et al. Bitumen has been defined as an involatile, adhesive, and waterproofing material derived from crude petroleum (as vacuum residue), or present in natural asphalt, which is completely or nearly completely soluble in toluene, and nearly solid at ambient temperatures (Lesueur 2009 Redelius and Soenen 2015). It is referred to as extra heavy oil or bitumen if it has lower than 10° API with the viscosity of up to 10 6 mPa s at the reservoir conditions (see Fig. On the other hand, crude oil is categorized as heavy oil if it has the viscosity between 10 3 and 10 5 mPa s, and lower than 20° API. The conventional light crude oil has viscosity as low as 10–100 mPa s at the reservoir temperature and pressure, and greater than 20° API gravity. The generic term heavy oil has been arbitrarily used to describe both the heavy oils that require thermal stimulation of recovery from the reservoir and the bitumen (or extra-heavy oil) in bituminous sand formations from which the heavy bituminous material is recovered by mining operation (Speight 2006). Heavy oil is an important energy resource with commercial availability in several places around the world including Canada, Venezuela, USA, China, etc. Therefore, there is room for further improvement on the viscosity modeling of bitumen–solvent system for wider applications. Thus, no model has been found to have absolute capability to predict the viscosity for all mixtures. Available reports revealed that the accuracy of a model to predict the viscosity of bitumen–solvent mixtures depends on various factors including the type and concentration of solvents, and the properties of the bitumen. The aim of this article is to present a concise survey of the various viscosity models that have been proposed to predict the viscosity of bitumen–solvent mixtures, and make comparative discussion on their applicability. Therefore, modeling and predicting viscosity of bitumen–solvent mixture has become an important step in the development of solvent-assisted system. Addition of organic solvents or diluents with bitumen leads to significant viscosity reduction and forms the basis for the steam/solvent-assisted recovery methods of extra-heavy oil and bitumen. High viscosity, which is sometimes greater than 1 million mPa s, at the initial reservoir conditions, is a major challenge to recovery, production, and transportation of bitumen. Viscosity is the resistance of a material to continuous deformation exerted by shear force.
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