Most of the natural gas that we use is called dry.. It generally consists of 95% methane, 3% ethane, propane, and butane, and 2% non-hydrocarbon gases such as carbon dioxide, nitrogen, or helium (EPA 2010).On the other hand, some forms of natural gas-called âwetâ - contain up to 20% of ethane, propane, and butane.ost of the natural gas that we use is called dry.. It generally consists of 95% methane, 3% ethane, propane, and butane, and 2% non-hydrocarbon gases such as carbon dioxide, nitrogen, or helium (EPA 2010).