Headspace gas analysis refers to the determination of the interstitial light hydrocarbon gases that collect in the headspace above canned cuttings by gas chromatography/flame ionization detection (GC/FID). The abundance and composition of the gas can be used to indicate the presence of source rocks, and also reservoir hydrocarbons. The chemical composition includes (methane, ethane, ethylene, propane, propylene, butanes, pentanes, C6+, carbon dioxide, nitrogen and oxygen).