Petroleum, IndianaPetroleum is an unincorporated community in Nottingham Township, Wells County, Indiana, United States. Petroleum has a population of 196.HistoryPetroleum was platted in 1894, and is so named because it was laid out in an oil field. The post office at Petroleum has been in operation since 1894.DemographicsThe United States Census Bureau designated Petroleum as a census designated place in the 2022 American Community Survey.