ABSTRACT
Categorizing hydrocarbons can be complex, "heavy oils" can simply be characterized based on their tank flow properties, such as saturation and a viscosity of approximately 100 centipoises (100 millipascal-seconds) or higher. These heavy oils constitute a significant global hydrocarbon resource, if fully extracted it will meet a substantial demand. The processes of effectively recovering heavy oils pose significant challenge.
The initial stage entails the extraction of natural hydrocarbons under the initial pressure decline of the reservoir, typically accounting for about 20-30% of the well's reserves. The second stage commences as the well pressure decreases and is unable to produce the well, and during this phase, oil recovery employs secondary methods like water flooding, enabling the retrieval of approximately 40-50% of the reservoir's hydrocarbons. The well is considered depleted when the recovery rate no longer economical. At this juncture, the third phase, known as Enhanced Oil Recovery (EOR) or tertiary oil recovery, is initiated. Enhanced oil recovery involves the use of external energy as a means in maximizing the recovery of viscous crude oil reserves. Given the ever-increasing energy demand, Enhanced oil recovery holds immense potential for efficiently tapping into crude oil reserves and reaping substantial economic advantages.
EOR encompasses both thermal and non-thermal techniques aimed at altering the properties of crude oil within the reservoir, such as its mobility ratio and viscosity, facilitating better flow within the reservoir and thereby enhancing recovery rates. Among the various EOR methods, thermal enhanced oil recovery takes precedence and is the primary focus of this research. This study offers a comprehensive overview of the classifications of thermal and non-thermal enhanced oil recovery methods. Furthermore, it presents an in-depth review of temperature effect on thermal EOR technique employed for optimizing the recovery of heavy oils, incorporating numerical analysis and the development of computer programs to predict reservoir behavior in such scenarios.
