Evaluating flue gas geo-sequestration and EOR in fractured reservoirs through simulated synergistic reservoir characteristics and injection kinetics

Abstract

The global reliance on hydrocarbon resources and fossil fuels has resulted in a significant surge in carbon dioxide emissions, necessitating urgent measures to mitigate greenhouse gas emissions. Integrating CO₂ storage with enhanced oil recovery (EOR) presents a promising solution for reducing emissions and enhancing oil recovery by sequestering CO₂ within oil reservoirs, especially in fractured carbonate reservoirs. The research utilized the Eclipse simulator to model different gas injection scenarios in a crude oil reservoir, focusing on assessing the effectiveness of CO₂ and flue gas geo-sequestration and EOR, performing sensitivity analyses on reservoir characteristics, and evaluating the impact of varying injection rates on gas storage capacity and oil recovery factor. The findings demonstrated a superior capacity to store flue gas (150 MMSCF) in comparison to CO₂ (85 MMSCF) and flue gas injection demonstrated better reservoir pressure maintenance than CO₂ injection, while CO₂ injection resulted in a higher oil recovery factor of 52% compared to flue gas injection at 36%. Additionally, analysis of reservoir characteristics in gas storage revealed that, an augmentation in reservoir porosity, permeability, and injection rate substantiated an increase in gas storage capacity for both CO₂ and flue gas injection. Except for CO₂ storage, which displayed a normal distribution trend in the permeability analysis. Additionally, it was elucidated that higher reservoir pressure and temperature in flue gas injection resulted in a reduction of gas storage capacity, while these variables exhibited relative stability in the context of CO₂ injection. The scrutiny of gas storage in reservoir characteristics unveiled substantial alterations in porosity and injection rate, signifying their pivotal roles in influencing gas storage capacity. In the EOR study, heightened reservoir pressure, temperature, permeability, and injection rate collectively contributed to an amplified oil recovery for both flue gas and CO₂, except CO₂ injection demonstrated a normal distribution trend in oil recovery within the permeability analysis. Conversely, higher porosity was associated with a decrease in oil recovery. The findings of this research provide valuable insights into the feasibility and effectiveness of employing flue gas geo-sequestration and EOR in fractured carbonate reservoirs.