| Abstract |
Aqueous solutions of gas nanobubbles (NBs) possess unique properties that make them a promising alternative to traditional water flooding and enhanced oil recovery (EOR) methods. NBs are stable for weeks to months, which is crucial for practical deployment, and their nanometer size enables penetration into narrow porous spaces in tight formations, which are particularly important targets for EOR. This study presents the first experiments testing of N2-based NBs for oil recovery enhancement using spontaneous imbibition, comparing the NB performance to that of distilled water (DW). The tests were conducted on two rock samples: Minnesota Northern Cream (MNC) carbonate and Berea sandstone, under two wettability conditions (strongly water-wet for both rocks and strongly oil-wet for MNC) and a wide range of temperatures and pressures (ambient to 90 psi and 120 °C). For both rocks and wettability conditions, NBs generally enhance the oil recovery compared to DW at most temperatures and pressures, except for the highest tested pressure (90 psi), where the difference was not statistically significant. The greatest enhancement was obtained from oil-wet MNC at 45 psi and 120 °C, which neared the recovery from water-wet MNC under the same conditions. Additional experiments with N2 NB solutions of varying gas–liquid quality (amount of N2 gas per unit liquid volume) revealed that higher gas–liquid ratios led to lower NB stability and progressively lower oil recoveries. The study further explores potential mechanisms for the recovery enhancement by NB solutions, discussing the effects of wettability, temperature, pressure, and gas quality and considers the implications for practical NB-based EOR applications. |
| Authors |
Hala I. El-Naggar   , Amira Taman , Ramzi Ali , Maziar Arshadi , Dev Joshi , Sheikh F. K. Joy , Nagi Nagarajan , Jan Kubelka , Lamia Goual , Mohammad Piri
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