COMPOSITIONAL SIMULATION OF CO2 ENHANCED OIL RECOVERY IN UNCONVENTIONAL LIQUID RESERVOIRS
ABSTRACT
After implications of hydraulic fracturing operations, the commercial production of tight formations and shale plays were successfully achieved in past decades. The
industry now shifts its interest in enhancing the production after the stimulation treatment. Experimental results showed promising oil recovery potential using CO2. This study utilizes commercial simulation software to investigate the oil production mechanisms from the matrix into the fracture by simulating two laboratory experiments, and evaluates the potential of using CO2 huff n puff process to enhance the oil recovery in liquid rich shale plays with nano-Darcy range permeability values. This study fully explores the mechanisms contributing to the oil recovery with numerical modeling of experimental works, and performs a thorough investigation on the effects of various parameters on oil recovery. The core scale modeling involves two methods of determining properties used to construct the 3D heterogeneous models. The experimental findings are then upscaled to a field case model where a single stage hydraulic fracture is modeled. The effects of reservoir properties and operational parameters on oil recovery are then investigated. Diffusion is proven to be the dominating oil recovery mechanism with laboratory scale modeling. However, it is not as significant in the field scale model. Due to the difference in mass transfer mechanism between the core scale model and the field scale model, the two models are sensitivity to different parameters. The CO2 huff n puff process was found beneficial in both models in terms of enhancing the ultimate oil recovery in unconventional liquid reservoirs.
