Light hydrocarbons can react by the means of free radicals.The double bonds of alkenes are easy to rupture.There is surplus bond force in solid surface,which can adsorb light hydrocarbons.When the sediment surfaces adsorb light hydrocarbons,it follows the theory of solid surface adsorption.Firstly,light hydrocarbons adsorbed physically,the molecule interval minish and the Vandwa force augment.Then the adsorbed bond C-H of alkyl hydrocarbons turn into Cand H,and the adsorbed bond.