By utilizing surface geochemical data; one may effectively delineate geochemical anomalies and determine the range of vertical migration of hydrocarbon. Nevertheless; this merely meets the basic requirements for oil and gas exploration and is hence unsatisfactory. Through an analysis of vertical geochemical data and surface geochemical free hydrocarbon data; the present paper has made a preliminary discussion on the appliccation of geochemical kinetic indices to the determination of preservation conditions and buried depth of oil and gas accumulations.