Compositional Simulation Evaluation of Miscible Gas Injection Performance in Tight Oil Formation

Abstract Studying the performance of different techniques to improve oil recovery of tight oil reservoirs have become the main focus of many researchers because of the significant contribution of these reservoirs to the USA daily oil production. Recent studies have shown possibility of using EOR methods to improve oil recovery of tight and ultra-tight oil reservoirs as an attempt to encouagre the development of these reservoirs. This paper studies the feasibility and limitations of applying miscible gas flooding to enhancing oil recovery of tight and ultra-tight formation. A compositional simulation study was conducted and three main factors were used to study the performance of gas flooding; formation permeability, distance between wells, and gas injection period. Five permeability values, 1 md, 0.1 md, 0.01 md, 0.001 md, and 0.0001md, were used to build five simulation models then these models were used to study the performance and define the limitations of gas flooding process for each model. The results of the first part of the compositional simulation study show that the oil recovery has been improved when the miscible gas displacement process was applied to a formation that has permeability larger than 0.01 md becuase gas flooding did not significantly improve oil recovery for the models that have formation permeability less than 0.01 md. Second, we used the distance between the injection and production wells and gas injection period to investigate the performance and the limitations of applying gas flooding on each models. As a result of that, it has been found that formation permeability has a significant effect on the selection of well spacing. Forthermore, the study helped to recommend the well spacing that should be considered for different formation permeability values. Finally, this study promotes the understanding of implementing the miscible gas flooding in tight and ultra-tight oil formation and helps in the selection of the best candidate to apply gas flooding base on its permeability. Furthermore, it helps in optimize the well spacing of tight formation if gas flooding process is considered in future.