The effect of natural fractures on CO2 storage performance and oil recovery from CO2 and WAG injection in an Appalachian basin reservoir

Abstract

AbstractNatural fractures affect both the oil recovery from the enhanced oil recovery (EOR) process and the associated CO2 storage during and after EOR. The main objective of this study is to evaluate two performance parameters: (1) oil recovery during CO2 and water alternating gas (WAG) injection, and (2) CO2 storage, during and after EOR, in a fractured oil reservoir of the Appalachian basin. While previous studies have shown the potential of CO2‐EOR to enhance oil recovery in the Appalachian basin, this work investigates WAG performance in comparison to continuous CO2‐EOR. A compositional numerical modeling approach was used to quantify the incremental oil recovery stemming from incorporating natural fractures. History matching of primary production and CO2 huff‐and‐puff pilot test for a well producing from a depleted oil field in Ohio was used to assign the fracture network parameters in the dual continuum model. The scenarios modeled include continuous CO2 and WAG injection under two injection pore volumes. Each scenario is followed by a CO2 storage phase. These simulations help evaluate the performance of different scenarios in terms of oil recovery and CO2 storage. Simulation results show how oil recovery and CO2 storage vary significantly as a function of operational parameters. The results also show the amount of CO2 stored during WAG injection is significantly lower than that stored during the storage phase at the end of oil recovery. In addition, the operational parameters during WAG affect the amount of CO2 stored at the end of following storage phase. © 2020 Society of Chemical Industry and John Wiley & Sons, Ltd.