Step 1: Understanding the Concept:
The question asks about the geological association of natural gas with other minerals or resources.
Step 2: Detailed Explanation:
Natural gas is a fossil fuel, formed from the decomposition of organic matter under heat and pressure over millions of years. This formation process is very similar to that of petroleum (crude oil). As a result, deposits of natural gas are most commonly found trapped in underground reservoirs along with petroleum. The gas can be dissolved in the oil or exist as a separate 'gas cap' above the oil. While some natural gas is also found associated with coal deposits (coal-bed methane), its primary and most significant association is with petroleum.
Step 3: Final Answer:
Natural gas is most commonly found with petroleum.