Adsorption based realistic molecular model of amorphous kerogen

Area of Science:

• Geochemistry
• Computational Chemistry
• Materials Science

Background:

• Kerogen, a complex organic macromolecule, plays a crucial role in subsurface gas behavior.
• Understanding kerogen's interaction with gases like N₂ and CO₂ is vital for energy applications.
• Existing kerogen models require refinement due to organic matter's inherent complexity.

Purpose of the Study:

• To simulate and analyze N₂ and CO₂ gas adsorption on diverse kerogen models.
• To validate simulation results against experimental data for accuracy.
• To elucidate the differential adsorption mechanisms of N₂ and CO₂ on kerogen.

Main Methods:

• Grand Canonical Monte Carlo (GCMC) and molecular dynamics (MD) simulations were employed.
• Three distinct kerogen models were constructed based on analytical data (¹³C-NMR, XPS, XANES).
• Simulated adsorption isotherms were compared with experimental data from physical samples.

Main Results:

• GCMC/MD simulations showed excellent agreement with experimental N₂ and CO₂ adsorption isotherms.
• Kerogen models accurately predicted N₂/CO₂ uptake across various pressures.
• CO₂ exhibited stronger interactions, leading to subsurface penetration, while N₂ remained surface-adsorbed.

Conclusions:

• Simulations provide a reliable method for studying gas adsorption in kerogen.
• Kerogen's role in gas separation and transport within organic-rich shale is significant.
• Findings support kerogen's importance in CO₂ sequestration and enhanced oil recovery (EOR).