Hydrocarbon gases generated at deeper depths by thermal cracking of sedimentary organic matter into hydrocarbon liquids and gases. Thermogenic gas is cogenetic with oil, and is known as primary thermogenic gas. At high thermal maturity levels, as thermal cracking increases, secondary thermogenic gas is associated with the cracking of oil at high temperatures into gas. Thermogenic gas can be dry, or can contain significant concentrations of “wet gas” components (ethane, propane, butanes) and condensate (C5+ hydrocarbons).