Separation of solid and liquid components in organic-rich chalks using NMR relaxation

Liu, Yunke; Wang, Xinglin; Hirasaki, George J.; Vinegar, Eva G.; Vinegar, Harold J; Singer, Philip M.

doi:10.1016/j.fuel.2022.126223

Cited by 6 publications

(11 citation statements)

References 48 publications

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“…The universal form T 1 ∝ f 0 0.6 above f 0 > 100 MHz for all three systems shows the lack of dependence of T 1 on the level of confinement for heptane, analogous to T 1 plateauing at high η/ T for viscous fluids. Furthermore, the functional form T 1 ∝ f 0 0.6 is consistent with measurements of heptane confined in organic-rich chalk . In general, a power-law dependence T 1 ∝ f 0 β suggests relaxation by RMTD (reorientations mediated by translational displacements) .…”

Section: T 1 Dispersionsupporting

confidence: 80%

“…In the slow-motion (i.e., high viscosity) regime defined as ω 0 ⟨τ⟩ ≫ 1, T 1 > T 2 and there is dispersion in T 1 . For crude oils and polymers, the transition ω 0 ⟨τ⟩ ≃ 1 occurs at a viscosity of η ≃ 6.4 × 10 3 cP/ f 0 (at 25 °C) for f 0 in MHz units . A similar concept exists for fluids under nanoconfinement, where ⟨τ⟩ increases with the degree of confinement.…”

Section: T 1 Dispersionmentioning

confidence: 84%

“…Furthermore, the functional form T 1 ∝ f 0 0.6 is consistent with measurements of heptane confined in organic-rich chalk. 41 In general, a power-law dependence T 1 ∝ f 0 β suggests relaxation by RMTD (reorientations mediated by translational displacements). 42 Further investigations are underway to determine whether the dynamic molecular modes P(τ) can give insights into the RMTD mechanism and the surface topography.…”

Section: ■ T 1 Dispersionmentioning

confidence: 99%

“…Interestingly, Figure 5 indicates that the pore-size distribution in kerogen is broader than for typical zeolites used in the petrochemical industry. 23−26 A similar derivation of the pore-size distribution from T 1 is not presented due to strong cross-relaxation effects in T 1 , 41 which are not present in T 2 . Cross-relaxation has a tendency to average out and narrow the measured T 1 distribution from all 1 H in contact with each other, via spin diffusion (a.k.a.…”

Section: The Journal Ofmentioning

confidence: 99%

“…A similar derivation of the pore-size distribution from T 1 is not presented due to strong cross-relaxation effects in T 1 , which are not present in T 2 . Cross-relaxation has a tendency to average out and narrow the measured T 1 distribution from all 1 H in contact with each other, via spin diffusion (a.k.a.…”

Section: T 2 Residual Dipolar Couplingmentioning

confidence: 99%

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Effect of Nanoconfinement on NMR Relaxation of Heptane in Kerogen from Molecular Simulations and Measurements

Parambathu

Chapman

Hirasaki

et al. 2023

J. Phys. Chem. Lett.

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Kerogen-rich shale reservoirs will play a key role during the energy transition, yet the effects of nanoconfinement on the NMR relaxation of hydrocarbons in kerogen are poorly understood. We use atomistic MD simulations to investigate the effects of nanoconfinement on the 1H NMR relaxation times T 1 and T 2 of heptane in kerogen. In the case of T 1, we discover the important role of confinement in reducing T 1 by ∼3 orders of magnitude from that of bulk heptane, in agreement with measurements of heptane dissolved in kerogen from the Kimmeridge Shale, without any models or free parameters. In the case of T 2, we discover that confinement breaks spatial isotropy and gives rise to residual dipolar coupling which reduces T 2 by ∼5 orders of magnitude from the value for bulk heptane. We use the simulated T 2 to calibrate the surface relaxivity and thence predict the pore-size distribution of the organic nanopores in kerogen, without additional experimental data.

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Section: T 1 Dispersionsupporting

confidence: 80%

Section: T 1 Dispersionmentioning

confidence: 84%