Study of EOR-CO2 Miscible Flooding Performance Using Compositional Reservoir Simulation with Local Grid Refinement
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COv2 injection in oil reservoirs has been widely accepted as an effective technique for enhanced oil recovery (EOR), which has been applied by the oil industry for over 40 years. Concerns over greenhouse gas emissions are leading to the investigation and realization of its potential as a carbon storage method in recent years. To achieve better miscibility and sweep efficiency for COv2 flooding, production performance needs to be optimized. However, optimization of production performance remains a challenging task in the upstream oil and gas industry due to the physical and/or financial uncertainties. In this study, a commercial reservoir simulator has been used to analyze optimum development strategies for COv2 miscible flooding. Since grid-refinement sensitivity is an extremely troublesome problem in many compositionally enhanced solvent simulations, the effect of local grid refinement on conducting COv2 flooding simulation will be first discussed in this study. Coarse reservoir models without local grid refinement are found to contribute to significant error. The nature of the errors resulting from numerical dispersion and the non-linearity of flash calculations depends on many variables, including petrophysics and fluid types; not using local grid refinement may result in overly optimistic or pessimistic production performances. The impacts of injection/production variables on oil recovery and COv2 storage are investigated. Injection variables studied include: injection pore volume, injection initiation timing and produced gas recycling while the production variables include producer bottomhole pressure, target oil rate and gas rate limits. Results show that optimum injection/ production strategies differ significantly for both light and heavy oil reservoirs. Overall, this study has determined a systematic general injection and production workflow to recover more oil and store more COv2 underground simultaneously.
Yeap, Wei Jian (2018). Study of EOR-CO2 Miscible Flooding Performance Using Compositional Reservoir Simulation with Local Grid Refinement. Master's thesis, Texas A & M University. Available electronically from