Diffusion/adsorption/dissolution coupling process of methane gas in kerogen nano-slit: Molecular simulation and a chemical potential-based mass transfer model

Understanding the multi-mechanism pore-scale gas transport in shale reservoirs plays a key role in estimating the reserves and production of shale gas. In this work, nano-scale slits confined by two pieces of quasi planar organic kerogen materials were modeled on the atomic scale. An integrated solution to quantify the complicated mass transfer process was proposed, involving adsorption thermodynamics analyses, diffusion coefficient calculations for free and adsorbed gas, and a chemical potential-based diffusion model to predict the dissolution process. The calculated density distribution in the slit agreed well with the Molecular Dynamics results, which proves the model's accuracy for various diffusion mechanisms.

Automated summary

Understanding the transport of gas in shale reservoirs is crucial for estimating reserves and production. This study models nano-scale slits with organic kerogen materials and proposes a solution to quantify mass transfer processes. The results are accurate and consistent with Molecular Dynamics results, validating the model's accuracy for different diffusion mechanisms.