(252b) Mesoscopic Modeling of Hydrocarbon Flow in Porous Media

Accurate and efficient numerical models for the flow of hydrocarbons in geological mesoscale confinement are considered essential research means in the development of enhanced geotechnical engineering for energy source recovery and carbon capture & storage in low-porosity, low-permeability rock formations. The interconnected pore channels in which hydrocarbons may reside and flow manifest a multiscale distribution of pore aperture sizes ranging from a few nanometers to a few micrometers. A numerical model for the flow of hydrocarbons that can efficiently handle both the sub-continuum fluid dynamics in the nanoscale and continuum (or continuum-like) fluid dynamics in the microscale at the same time is much desired. To address such needs, we have developed an atomistically-validated, mesoscopic fluid flow model based on the many-body dissipative particle dynamics (mDPD) method. Heptane and porous silica are chosen in this work as a representative fluid and porous medium, respectively. In this mesoscopic model, both heptane molecule and silica atoms are coarse-grained in mDPD beads and the mDPD model parameters have been calibrated with a rigorous upscaling approach using reference data, including experimental measurements and/or molecular dynamics (MD) simulations. Our numerical results have shown that this mDPD model accurately predicts the bulk pressure-density relation, surface tension, mass diffusivity and dynamic viscosity of heptane, and contact angle of heptane on silica surfaces. Our upscaling approach provides a unified way to calibrate the mDPD model for specific types of fluids and solids by coarse-graining from their underlying MD models. The coarse-grained models allow for much faster simulation compared to atomistic ones for systems that are relevant for the development of enhanced geotechnical engineering for energy source recovery and carbon capture and storage in low-porosity, low-permeability rock formations.