Multi-scale Imaging and Transport Properties in Shales from Experiments and Molecular Dynamics Simulations

Transport properties in shales were investigated using experimental and computersimulation methods. First, an experimental method based on a transient pressuredecay technique was further developed and used instead of classical Darcy core-flood methods. This has allowed measurement of the permeability of tight shale samples on much shorter time scales than by conventional methods. Second, molecular dynamics (MD) computer simulations were used to measure the diffusion coefficients of water and cations in a model clay sample. Measurements of the self-diffusion coefficient showed that the values increased with increasing water content. The results for Na-, Li-, and K-smectites are in satisfactory agreement with experimental and with other simulation results in the literature indicating that the clay interlayer space is an important route of transport for ions and water. The results also lend credibility to the correctness of the diffusion coefficients obtained from the current MD simulations.