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Investigation of Gas Injection Process For Enhanced Oil Recovery Using Scaling Analysis

Rahmani, Mojtaba | 2023

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 55936 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Ghazanfari, Mohammad Hossein; Fatemi, Mobeen
  7. Abstract:
  8. The process of gas injection is well-known for Enhanced Oil Recovery (EOR) among researchers in the past few decades. This process depends on both compositional effects and IFT reduction effects as the conditions approach miscibility. This study seeks to evaluate the interactions of these two fundamental mechanisms in the process of enriched gas injection for EOR. At first, we investigate the relative dominance of the key mechanisms, as well as composition paths, component and phase distribution, and component production via compositional simulation of the process of gas injection into 1D homogeneous porous media such as slim tube and core under immiscible and near-miscible conditions. Then, impacts of compositional effects, IFT reduction effects, and underlying heterogeneity on the overall performance of the process of gas injection into 1D and 2D heterogeneous porous media are analyzed. At first, the flow functions that were simultaneously determined using a history matching technique for the injected gas – volatile oil coreflood experiment conducted in the laboratory were used to estimate the flow functions of the same process at different conditions based on a new approach taking advantage of a trapping model and the improved normalization technique. Furthermore, the results of compositional simulations in 1D homogenous porous media demonstrated that whether pressurizing or enriching the injectant with intermediate components is employed to accomplish near-miscible conditions, due combined role of vaporizing gas drive and condensing gas drive, leads to distinct flow and thermodynamic behavior of the fluids and discrepancies in the extent of component extraction or dissolution, which, in turn, may impact the relative importance of compositional effects vs. IFT reduction effects and overall performance of the process. In addition, the results of compositional simulations in 2D heterogeneous porous media demonstrated that in the horizontal orientation, enrichment of the injectant with intermediate components – approaching miscibility – leads to higher gas saturation in the preferential routes, better local displacement efficiency compared to immiscible conditions, thus causing more severe viscous fingering and heterogeneity channeling to occur, which, in turn, impedes the viscous crossflow from unswept regions. However, in the vertical orientation, as the system approaches miscibility through enriching the injectant, the gas phase reflects its tendency to move upward towards upper regions of the porous media. In other words, due to vertical permeability, buoyancy driving forces, and gas tendency to move upward, the gravity-driven crossflow from unswept zones, thus leading to improved areal displacement efficiency in the upper regions of the porous media and enhanced oil recovery. Finally, a sensitivity analysis of ultimate oil recovery vs. heterogeneity scaling groups at near miscible conditions for enriched gas injection process in 2D heterogenous porous media was performed. A major disagreement between the results obtained at near-miscible conditions and those previously presented at immiscible or miscible conditions. Therefore, the dimensionless scaling groups proposed for immiscible and miscible conditions are not applicable for near-miscible conditions and new dimensionless scaling groups have to be derived
  9. Keywords:
  10. Gas Injection ; Enhanced Oil Recovery ; Near Miscible Condition ; Mixing ; Compositional Simulation ; Scaling Analysis ; Flow Functions

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