Subcontinuum mass transport of condensed hydrocarbons in nanoporous media

Kerstin Falk (1) , Benoit Coasne (2) , Roland Pellenq (1) , Franz-Josef Ulm (3) , Lydéric Bocquet (1)

1 MSE 2 - Multiscale Material Science for Energy and Environment
2 ICGM - Institut Charles Gerhardt Montpellier - Institut de Chimie Moléculaire et des Matériaux de Montpellier
3 MIT - Massachusetts Institute of Technology

Although hydrocarbon production from unconventional reservoirs, the so-called shale gas, has exploded recently, reliable predictions of resource availability and extraction are missing because conventional tools fail to account for their ultra-low permeability and complexity. Here, we use molecular simulation and statistical mechanics to show that continuum description-Darcy's law-fails to predict transport in shales nanoporous matrix (kerogen). The non-Darcy behaviour arises from strong adsorption in kerogen and the breakdown of hydrodynamics at the nanoscale, which contradict the assumption of viscous flow. Despite this complexity, all permeances collapse on a master curve with an unexpected dependence on alkane length. We rationalize this non-hydrodynamic behaviour using a molecular description capturing the scaling of permeance with alkane length and density. These results, which stress the need for a change of paradigm from classical descriptions to nanofluidic transport, have implications for shale gas but more generally for transport in nanoporous media.

Domaines: Physique [physics]

Kerstin Falk, Benoit Coasne, Roland Pellenq, Franz-Josef Ulm, Lydéric Bocquet. Subcontinuum mass transport of condensed hydrocarbons in nanoporous media. Nature Communications, 2015, 6 (1), ⟨10.1038/ncomms7949⟩. ⟨hal-02015075⟩