Limitation of EOR Applications in Tight Oil Formation

Abstract Tight oil reservoirs have become one of the main forces of oil production growth in the USA. Only 3% to 7% of the oil can be recovered under primary depletion. Further improvement in oil recovery in tight oil reservoirs can be achieved by applying gas flooding or huff ‘n’ puff. However, these methods have limitations, especially when dealing with ultra-low permeable formations. Hence, the objective of this study was to discover the limitations of EOR methods in tight formation. A 2D compositional simulation model was used to investigate the limitations of applying gas flooding and huff ‘n’ puff in a tight formation. The results were compared under distinct scenarios and conditions. Distinct values of well spacing were used to identify the optimal well spacing. Different average permeability values were used to study the effect of permeability value on the EOR performance in tight formation. The Simulation Model results showed a potential of applying EOR in tight formation under specific conditions. Well spacing optimization has a significant effect on the gas flooding performance in tight formations. Hence, it is recommended to identify the well spacing before commencing gas flooding or huff ‘n’ puff. This simulation study showed any formation with a permeability less than 0.01 md should not be considered for gas flooding due to gas injectivity issues, long injection time, and long depletion time. Huff ‘n’ puff showed better results and more oil recovery at a permeability less than 0.01 md. Simulation results showed that any formation with a permeability greater than 0.1 md may be considered for gas flooding because of the following reasons: gas flooding showed a better recovery factor compared to the huff ‘n’ puff method; short depletion time was needed to start gas injection; and gas flooding required less injection time and provided long well spacing. This study increases understanding of the EOR factor in a tight formation. The results of the study showed the limitations of the EOR using simulation approaches. Knowing the disadvantages and limitations of EOR in tight formations will lead to improving the efficiency of EOR in tight formations.