Department of Chemical and Biomolecular Engineering, Rice University, 6100 Main Street, Houston, Texas77005, United States.
Department of Chemical and Biomolecular Engineering, University of Delaware, 150 Academy Street, Newark, Delaware19716, United States.
J Phys Chem Lett. 2023 Feb 2;14(4):1059-1065. doi: 10.1021/acs.jpclett.2c03699. Epub 2023 Jan 24.
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 H NMR relaxation times and of heptane in kerogen. In the case of , we discover the important role of confinement in reducing 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 , we discover that confinement breaks spatial isotropy and gives rise to residual dipolar coupling which reduces by ∼5 orders of magnitude from the value for bulk heptane. We use the simulated to calibrate the surface relaxivity and thence predict the pore-size distribution of the organic nanopores in kerogen, without additional experimental data.
富有机质页岩储层将在能源转型中发挥关键作用，但纳米限域对干酪根中碳氢化合物 NMR 弛豫的影响仍不清楚。我们使用原子分子动力学模拟研究了纳米限域对干酪根中庚烷的 H NMR 弛豫时间 和 的影响。对于 ，我们发现限域在将其从庚烷本体中降低约 3 个数量级方面起着重要作用，这与从 Kimmeridge 页岩中溶解的庚烷的测量结果一致，而无需任何模型或自由参数。对于 ，我们发现限域破坏了空间各向同性，并产生了残余偶极耦合，从而将其从庚烷本体的值降低了约 5 个数量级。我们使用模拟的 来校准表面弛豫率，然后预测干酪根中有机纳米孔的孔径分布，而无需额外的实验数据。
