Integrated Study on the Applicability of Co2-EOR in Unconventional Liquids Rich Reservoir

Unconventional Liquids Rich Reservoirs (ULR) such as Bakken, Niobrara, and Eagle Ford have become the main target for oil and gas investors as conventional formations started to deplete and diminish in number. These unconventional plays have a huge oil reserve; however, the predicted primary oil recovery is still low as an average of 7.5 %. Unconventional Improved Oil Recovery (UIOR) techniques are still a new concept in the oil industry because there is no commercial project for any IOR technique so far. Injecting carbon dioxide (CO2) might be the most potential strategy to improve oil recovery in such complex plays.;In this study, three different approaches were combined to investigate the applicability of CO2-EOR in these unconventional reservoirs. Firstly, experimental data analysis for the feasibility of CO2-EOR was conducted on 95 cases of natural preserved core samples collected from different shale formations. Secondly, a numerical simulation study was conducted to upscale the reported experimental-studies outcomes to the field conditions. Thirdly, CO2-EOR performances in some of the fields' pilots performed in Bakken formation were matched and analyzed by using numerical simulation methods.;This study found that the kinetics of oil recovery process in productive areas and CO2-diffusivity level in the field scale of ULR are the keys to perform a successful CO2-EOR project. The results also diagnosed the gap between CO2 performances in lab-conditions versus to what happened in field pilots. Geomechanics coupling has a clear effect on CO2-EOR performance; however, different geomechanics approaches have a different validity in these shale plays. Finally, this research provided deep insights on how CO2-EOR is different in conventional reservoirs as in unconventional formations.