Petroleum products can be generally divided into four categories: gas (propane and butane), light distillate oil (gasoline and naphtha), distillate oil (kerosene, gas oil, heating oil and diesel oil) and residue (including fuel oil, heating oil, heavy diesel oil, heavy industrial fuel and marine oil). At present, some oil products closely related to chemical products in the futures market are: gasoline, naphtha, diesel oil and fuel oil.