Optimization of steam assisted gravity drainage, electrical Joule’s heating, and thermal-chemical processes for heavy oil reservoirs
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Thermal enhanced oil recovery techniques have been considered as the best approach to produce heavy oil, however, not all thermal methods are appropriate or effective for oil production from every heavy oil reservoir. Therefore, this research study aims to investigate how reservoir and operational parameters affect certain thermal enhanced oil recovery methods (steam assisted gravity drainage, and low frequency electrical heating) and a hybrid thermal-chemical process (method which combines low frequency electrical heating with hot water and alkaline/co-solvent/polymer injection). In this master’s thesis, a compositional reservoir simulator, UTCHEM, was used to build the base case reservoir models. UTCHEM is a three-dimensional, multicomponent, multiphase reservoir simulator, which is mainly utilized to model chemical flooding processes. Besides modeling many features of chemical floods, the simulator can also handle complex phase behavior, heterogeneous porous medium properties. In this study, a modified version of UTCHEM, which includes a thermal module to model thermal recovery processes, was used to design steam assisted gravity drainage, low frequency electrical heating and hot water flooding periods and a geochemical module of UTCHEM was used for simulating chemical flooding part. Simulation results showed that a considerable increase in oil recovery is obtained when multiple SAGD well pairs are used. It is also observed that steam injection rate and heat loss have a significant influence on the steam assisted gravity drainage process. On the other hand, heat loss does not affect low frequency electrical heating method. It is deduced that low frequency electrical heating technique is not economically feasible and not very efficient to heat the reservoir. Therefore, low frequency electrical heating method can be used as a preheating application to lower the oil viscosity and, in turn, increase the injectivity in high viscous oil reservoirs. Finally, simulation results revealed that in the thermal-chemical process at the end of chemical flood, the amount of oil recovered is 80% of original oil in place (OOIP) where the oil recovery is only around 5% after hot water flooding. Thus, combining reservoir (pre)heating and chemical enhanced oil recovery methods has the potential to become a promising oil recovery method for heavy oil reservoirs.