Dependence of Methane Transport on Pore Informatics in the Amorphous Nanoporous Kerogen Matrix

Area of Science:

• Geochemistry and Petroleum Science
• Computational Materials Science
• Chemical Engineering

Background:

• Fluid transport in kerogen is primarily diffusion-driven, but its relationship with pore characteristics remains unclear.
• Experimental determination of pore informatics' influence on kerogen fluid transport is challenging.

Purpose of the Study:

• To investigate methane transport behavior in amorphous kerogen using molecular dynamics simulations.
• To characterize the impact of pore properties like connectivity and tortuosity on methane diffusion.

Main Methods:

• Molecular dynamics simulations were employed to model methane transport in kerogen matrices.
• Key pore properties (porosity, connectivity, size, tortuosity) were quantified.
• Self-diffusion coefficients (effective and total) were calculated based on free volume theory.

Main Results:

• Both effective and total self-diffusion coefficients decrease exponentially with methane loading.
• Discrepancies arise in transport estimations when pore connectivity is low, highlighting the importance of connected pores.
• Effective diffusion coefficients correlate with pore size and tortuosity, specifically increasing with (pore size/tortuosity)^2.

Conclusions:

• Accurate evaluation of fluid transport in kerogen necessitates considering connected pores, as unconnected pores do not contribute to actual transport.
• The study provides critical insights into kerogen pore informatics and their influence on methane transport, vital for shale gas exploration and development.