Compositional Analysis and Screening for Enhanced Oil Recovery Processes in Different Reservoir and Operating Conditions

The feasibility of different gases (CO2, N2, or Enriched Gas) and Water-Alternating-Gas (WAG) to maintain pressure and optimize oil recovery have been examined on a simple mechanistic reservoir model of considerably depleted saturated oil reservoir. The simulation study was conducted on 3-phase- 2D finely gridded compositional simulation model. A compositional model is necessary to account for mass transfer and changes in composition of a saturated oil system because the miscibility takes place through inter-phase mass transfer during the miscible solvent injection. Also the compositional study is indispensable to design the surface facilities to deal not only with the reservoir hydrocarbon fluid but also the solvents and water after their break-through. These surface facility operations include the separation of injected solvent, water and reservoir hydrocarbon fluids, and the treatment of solvent & produced water and their reinjection into the reservoir. Due to better mobility control WAG injection was found to be significantly more efficient than the gas injection. For more optimization a sensitivity study was conducted on the injection cycling and component ratios. A sensitivity study was also conducted on the following parameters to study its effect on the overall field’s recovery the composition of the produced oil. Some of these parameters include the completion of the injector well and the presence of a thief zone and its level of permeability For the good reservoir management a reliable prediction of oil and gas rate