Flaring associated natural gas is commonly employed in the oil and gas industry to reduce methane (CH4) emissions but generates carbon dioxide (CO2) and harmful pollutants, significantly contributing to air pollution and posing risks to public health.To mitigate this impact, M2X Energy Inc. has developed a small-scale, modular gas-to-methanol system.This system features an engine reformer that performs fuel-rich partial oxidation of wellhead gas to produce syngas-a mixture of carbon monoxide (CO) and hydrogen (H2)-followed by a downstream reactor for methanol synthesis.This study focused on computational fluid dynamics (CFD) modeling of the engine reformer to simulate partial oxidation chem., predict the rich-burn operating limit, and assess syngas quality, ultimately aiding in design and operational optimization.The CFD model, developed within a Reynolds-Averaged Navier-Stokes (RANS) turbulence framework, incorporated sub-models for turbulent combustion, a chem. mechanism with polycyclic aromatic hydrocarbon (PAH) pathways, and soot emissions to accurately capture the fuel-rich, turbulent jet ignition and combustion processes.Model validation against exptl. data showed good agreement across pre- and main-chamber pressures, apparent heat release rates, and exhaust gas concentrations of key species (H2, CO, CO2, CH4) for varying intake equivalence ratios.The model identified a rich-burn operating limit near a fuel-air equivalence ratio of 2.35, consistent with exptl. observations.Furthermore, syngas quality anal. revealed that extending the rich-burn limit through engine reformer optimization could enhance syngas production, contributing to higher methanol synthesis efficiency.