The process by which organic matter decomposes deep underground to form petroleum and its underlying kerogen matrix has so far remained a no man’s land to theoreticians, largely because of the geological (Millions of years) timescale associated with the process. Using reactive molecular dynamics and an accelerated simulation framework, the replica exchange molecular dynamics method, we simulate the full transformation of polymers such as cellulose and lignin into kerogen and its associated fluid phase under prevailing geological conditions. We observe in sequence the fragmentation of the cellulose and lignin molecular crystals and production of water, CO, CO2…, the development of an unsaturated aliphatic macromolecular phase, and its aromatization. The composition of the solid residue along the maturation pathway follows what is observed for natural kerogen and for artificially matured samples under confined conditions. After expulsion of the fluid phase, the obtained microporous kerogen possesses the structure, texture, density, porosity, and stiffness observed for mature type III kerogen and a microporous carbon obtained by saccharose pyrolysis at low temperature. As expected for this variety of precursor, the main resulting hydrocarbon is methane. The present work thus demonstrates that molecular simulations can now be used to quantitatively assess, such complex chemical processes as petrogenesis in fossil reservoirs and, more generally, the possible conversion of any natural product into bio-sourced materials and/or fuel. All content contained within this webinar is copyrighted by Dr. Roland Pellenq and its use and/or reproduction outside the portal requires express permission from Dr. Roland Pellenq.