MultiScale Materials Science for Energy and Environment (MSE2), The joint CNRS-MIT Laboratory, UMI CNRS 3466, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States.
Department of Civil and Environmental Engineering, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States.
Nano Lett. 2018 Feb 14;18(2):832-837. doi: 10.1021/acs.nanolett.7b04079. Epub 2018 Jan 18.
In a context of growing attention for shale gas, the precise impact of organic matter (kerogen) on hydrocarbon recovery from unconventional reservoirs still has to be assessed. Kerogen's microstructure is characterized by a very disordered pore network that greatly affects hydrocarbon transport. The specific structure and texture of this organic matter at the nanoscale is highly dependent on its origin. In this study, by the use of statistical physics and molecular dynamics, we shed some new lights on hydrocarbon transport through realistic molecular models of kerogen at different level of maturity [ Bousige et al. Nat. Mater. 2016 , 15 , 576 ]. Despite the apparent complexity, severe confinement effects controlled by the porosity of the various kerogens allow linear alkanes (from methane to dodecane) transport to be studied only via the self-diffusion coefficients of the species. The decrease of the transport coefficients with the amount of adsorbed fluid can be described by a free volume theory. Ultimately, the transport coefficients of hydrocarbons can be expressed simply as a function of the porosity (volume fraction of void) of the microstructure, thus paving the way for shale gas recovery predictions.
在页岩气日益受到关注的背景下，有机物质（干酪根）对非常规储层中烃类回收的精确影响仍有待评估。干酪根的微观结构的特点是具有非常无序的孔隙网络，这极大地影响了烃类的传输。这种有机物质的纳米尺度的具体结构和纹理高度取决于其来源。在这项研究中，我们通过统计物理学和分子动力学，对不同成熟度的干酪根的真实分子模型中的烃类传输进行了一些新的研究[Bousige 等人，《自然材料》2016 年，15 期，576]。尽管存在明显的复杂性，但各种干酪根的孔隙率控制的严重限制效应允许仅通过物种的自扩散系数来研究线性烷烃（从甲烷到十二烷）的传输。随着吸附流体量的增加，传输系数的减少可以用自由体积理论来描述。最终，烃类的传输系数可以简单地表示为微观结构孔隙率（空隙体积分数）的函数，从而为页岩气回收预测铺平了道路。
