Molecular anatomy and macroscopic behavior of oil extraction from nanopores by CO2 and CH4

Moh, Do Yoon; Zhang, Hongwei; Sun, Shuyu; Qiao, Rui

doi:10.1016/j.fuel.2022.124662

Cited by 13 publications

(16 citation statements)

References 39 publications

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“…In the shale oil exploitation, a composition analysis to the extraction oil is a routine for the quality assessment of crude oil. One prevailing method is the SARA analysis method according to the solubility difference . A fact is that the asphaltene content in most shale oil samples is pretty low.…”

Section: Resultsmentioning

confidence: 99%

“…The displacement efficiency can be reinforced with the increase of chain length and viscoelasticity . There are also some studies on the gas replacement of oil molecules in blind pores. , The carbon dioxide and methane show two different exchange modes for the extraction of decane molecules in calcite pores. The former preferentially exchanges the adsorbed decane molecules and then it turns to free decane molecules, while the latter shows an opposite exchange transition .…”

Section: Introductionmentioning

confidence: 99%

“…The former preferentially exchanges the adsorbed decane molecules and then it turns to free decane molecules, while the latter shows an opposite exchange transition. 43 In essence, both gas replacement and viscoelastic polymers flooding exert an external force to oil molecules. Nevertheless, the dynamic migration behavior of gas and oil in blind pore through a pore throat under reservoir pressure has been given little attention.…”

Section: Introductionmentioning

confidence: 99%

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Molecular Understanding on Migration and Recovery of Shale Gas/Oil Mixture through a Pore Throat

Hong

et al. 2022

Energy Fuels

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Shale gas/oil remaining in blind pores accounts for a large proportion in total reserves, which is urgent to be further exploited. Understanding the microscopic mechanism of gas/oil extraction from blind pores is critical to enhanced gas/oil recovery. In this study, we investigated the migration and recovery behavior of shale gas/oil mixture through a pore throat connecting blind pores and microfractures. Our simulations show that some oil molecules tend to migrate in the form of clusters, which increases their effective size and causes possible blockage of the pore throat. The recovery ratio of gas/ oil mixture has a strong dependence on the pore size. Below the critical size, which is smaller than the size of oil clusters, the pore throat would be blocked and the recovery ratio will decrease significantly. The heavy fractions of shale oil suppress the extraction of gas/oil molecules from blind pores by four inhibition mechanisms: edge adsorption, surface adsorption, throat blockage, and liquid bridge. The kerogen pore shows a stronger adsorption ability for gas/oil mixture than quartz pore, resulting in more residues in it. We also found that a higher gas/oil ratio can provide a larger driven force, leading to a higher recovery of methane and light fractions. These findings advance the understanding of the recovery mechanisms of remaining gas/oil in blind pores and provide a practical guideline on shale gas/oil exploitation.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Molecular Understanding on Migration and Recovery of Shale Gas/Oil Mixture through a Pore Throat

Hong

et al. 2022

Energy Fuels

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“…The rescaled MD and experimental data show very good agreement, thus highlighting the power of MD simulations of nanoscopic systems in understanding experimental data. It is worth noting that the diffusive nature of gas recovery facilitated by gas injection is the same as that of oil recovery from nanopores driven by gas injection. − …”

Section: Pore-scale Physics Of Shale Gas Recovery Dynamicsmentioning

confidence: 99%

Review on Pore-Scale Physics of Shale Gas Recovery Dynamics: Insights from Molecular Dynamics Simulations

et al. 2022

Self Cite

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Reliable prediction of gas recovery from shale formations is essential for achieving the full potential of shale gas. A distinguishing feature of shales is that nanoscale pores dominate their porosity. Hence, confinement and fluid−wall interactions modulate shale gas storage, transport, and recovery, which are neglected in conventional gas recovery models. Because these nanoscale effects can be simulated using molecular dynamics (MD), related works have proliferated. Here, we review MD modeling of shale gas recovery at the pore scale. The design and simulation protocols of MD systems for studying gas recovery are surveyed first. Then, the gas recovery in three scenarios, i.e., recovery of single-component gas, recovery of multicomponent gas, and gas recovery involving multiphase flows, are reviewed. In particular, works exploring and elucidating new pore-scale phenomena and guiding and validating new pore-scale continuum models are highlighted. Finally, we recommend best practices in MD shale gas studies and suggest several research directions.

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“…Among the unconventional sources, shale oil has aroused extensive interest attributed to its abundant reserves, continuous distribution, and easy exploitation in comparison with the existing primary fossil energy [ 4 , 5 , 6 ]. Shale oil is widely presented in nano-porous shale slit through physicochemical changes such as adsorption and deposition [ 7 , 8 , 9 , 10 ]. Some technologies such as horizontal drilling, hydraulic fracturing, and supercritical carbon dioxide (sCO 2 ) displacing methods have been developed to exploit shale oil [ 1 , 11 , 12 ].…”

Section: Introductionmentioning

confidence: 99%

Mechanism of Hexane Displaced by Supercritical Carbon Dioxide: Insights from Molecular Simulations

Song

Zhu

2022

Molecules

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Supercritical carbon dioxide (sCO2) has great potential for displacing shale oil as a result of its high solubility and low surface tension and viscosity, but the underlying mechanisms have remained unclear up to now. By conducting equilibrium molecular dynamics (EMD) simulations, we found that the displacing process could be divided into three steps: the CO2 molecules were firstly injected in the central region of shale slit, then tended to adsorb on the SiO2-OH wall surface and mix with hexane, resulting in loose hexane layer on the shale surface, and finally displaced hexane from the wall due to strong interactions between CO2 and wall. In that process, the displacing velocity and efficiency of hexane exhibit parabolic and increased trends with pressure, respectively. To gain deep insights into this phenomenon, we further performed non-equilibrium molecular dynamics (NEMD) simulations and found that both the Onsager coefficients of CO2 and hexane were correlated to increase with pressure, until the diffusion rate of hexane being suppressed by the highly dense distribution of CO2 molecules at 12 MPa. The rapid transportation of CO2 molecules in the binary components (CO2 and hexane) actually promoted the hexane diffusion, which facilitated hexane flowing out of the nanochannel and subsequently enhanced oil recovery efficiency. The displacing process could occur effectively at pressures higher than 7.5 MPa, after which the interaction energies of the CO2-wall were stronger than that of the hexane-wall. Taking displacing velocity and efficiency and hexane diffusion rate into consideration, the optimal injection pressure was found at 10.5 MPa in this work. This study provides detailed insights into CO2 displacing shale oil and is in favor of deepening the understanding of shale oil exploitation and utilization.

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Molecular anatomy and macroscopic behavior of oil extraction from nanopores by CO2 and CH4

Cited by 13 publications

References 39 publications

Molecular Understanding on Migration and Recovery of Shale Gas/Oil Mixture through a Pore Throat

Molecular Understanding on Migration and Recovery of Shale Gas/Oil Mixture through a Pore Throat

Review on Pore-Scale Physics of Shale Gas Recovery Dynamics: Insights from Molecular Dynamics Simulations

Mechanism of Hexane Displaced by Supercritical Carbon Dioxide: Insights from Molecular Simulations

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