A natural gas reservoir is a geological formation that contains significant amounts of natural gas, which is primarily composed of methane. These reservoirs are typically found in porous rock layers, where gas can accumulate over time. The gas is often trapped beneath impermeable rock layers, preventing it from escaping to the surface. Natural gas reservoirs can be located onshore or offshore and are explored and extracted using various techniques. The extraction process involves drilling wells to access the gas, which can then be processed and transported for use in heating, electricity generation, and as a fuel source in various industries.