Alternating N 2 gas injection as a potential technique for enhanced gas recovery and CO 2 storage in consolidated rocks:
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Alternating N2 gas injection as a potential technique for enhanced gas recovery and CO2 storage in consolidated rocks: an experimental study Nuhu Mohammed1 · Abubakar Jibrin Abbas1 · Godpower C. Enyi1 · Salihu M. Suleiman1 · Donatus E. Edem1 · Muhammad Kabir Abba1 Received: 21 April 2020 / Accepted: 11 June 2020 © The Author(s) 2020
Abstract The promotion of enhanced gas recovery (EGR) and CO2 storage is still shrouded in contention and is not well accepted, due to the excessive in situ C O2 mixing with the nascent natural gas. This adulterates the recovered CH4 and thus results in a high sweetening process cost thereby making the technique impractical. This has not only limited the field application of EGR in actual projects to a few trails but renders it uneconomical. This study aims to present, experimentally, alternating N2 injection as a potential technique for EGR and CO2 storage in sandstone rock cores. A laboratory core flooding experiment was carried out to simulate a detailed process of unsteady-state methane (CH4) displacement using Bandera grey core plug. This was carried out at 40 °C, 1500 psig, and 0.4 ml/min injection rate by alternative injection of N 2 and C O2 in succession designed to suit the application based on optimum operating conditions. The results show that both C O2 storage capacity and CH4 recovery improved significantly when gas alternating gas (GAG) injection was considered. The best results were observed at lower N2 cushion volumes (1 and 2 PV). Therefore, the GAG injection method with N2 as cushion gas can potentially increase both CO2 storage and C H4 recovery of the gas reservoir. This technique if employed will assert the current position and provide vital information for further researches aimed at promoting environmental sustainability and economic viability of the EGR and CO2 sequestration processes. Keywords Dispersion coefficient · Enhanced gas recovery · Cushion gas · Breakthrough · Concentration profile List of symbols yCO2 CO2 mole fraction yN2 N2 mole fraction D Diffusion coefficient, m2/s Q Flow rate mil/min tD Dimensionless time xD Dimensionless distance d Characteristic length scale, m KL Longitudinal dispersion, m2/s L Core sample length, mm Lexp Experimental length, m μ Viscosity, cP P Pressure, psig
T Temperature, K u Interstitial velocity, m/s ϕ Core porosity, % α Dispersivity, m τ Tortuosity Pe Péclet number Pem Medium Péclet number PV Pore volume r Radius of core sample, m λ90 Lambda function at 90% of effluent concentration λ10 Lambda function at 10% of effluent concentration
Electronic supplementary material The online version of this article (https://doi.org/10.1007/s13202-020-00935-z) contains supplementary material, which is available to authorized users.
CO 2 emissions are generalized as a significant factor responsible for inhibiting climate change that later results to increase in environmental temperature (global warming). It was predicted that there will
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