Numerical and Mathematical Modeling of In-situ Reflux (ISR) Recovery Process
Creators: name: Zeidani, Mohammad
Publisher: name: Graduate Studies
Year: 2024
Subjects: subject: In Situ Reflux
subject: Solvent
subject: Education--Technology

description: In-Situ Reflex (ISR) is a novel solvent-based process that utilizes resistive electric heaters to vaporize solvent and recycle mobilized water downhole. ISR promises a significant reduction in greenhouse gas emissions through the elimination of steam generation and water handling facilities at the surface as well as effectively vaporizes the injected fluid along a wellbore. However, the economic viability of this process is highly dependent on the in-situ refluxing of a solvent which requires an in-depth understanding of the process and associated challenges numerically and analytically. In modeling the SAGD (steam assisted gravity drainage) process, optimal operating conditions rely on a relatively constant temperature profile across the major portion of a steam chamber that leads to an excessive energy input requirement. However, ISR optimal operating conditions tend to exhibit different temperature profiles as a result of changing thermal recovery to a solvent-diluting mechanism. As such, employing a SAGD analytical model results in misunderstanding the ISR fundamental thermodynamics and hindering further optimization of the process. The traditional method for injecting a mixture at high temperatures in the context of hybrid processes involving solvent and steam applications was often based on the assumption that increased energy input would result in better incremental recovery rates. Numerous numerical simulations on the amalgamation of solvent and steam have provided a wide range of operating circumstances, demonstrating the possibility of high-temperature regimes even for lighter solvents like C3 and C4. The current study focuses on the technical optimization of key performance parameters that are integral to the azeotropic in-situ reflux (AISR) process. The optimal operating temperatures for both injector and producer heaters were determined by the application of a sensitivity analysis. These temperatures were chosen to decrease the retained solvent per volume of the bitumen recovery factor. Additionally, a determined attempt was made to carefully recycle the retrieved solvent within a reservoir in an ideal manner, which was accomplished by using a producer heater to mimic the core ideas of the AISR concept. An unsteady-state semi-analytical model has been developed for predicting ISR performance. The developed model has been validated using numerical simulation data and is capable of properly predicting a temperature distribution in a steam-solvent gaseous chamber in the presence of a fixed source of heat in an injector. This model includes fixed heat sources in both injectors and producers to represent the resistive heater concept, capture the reflux idea, and evaluate the contribution of a refluxed solvent to reducing solvent usage. In addition, the model helps better understand the phase behavior and the effectiveness of various solvents in further analyzing and determining the optimum downhole operating conditions and improving the overall ISR performance and its economic viability.