Hydrocarbon is a direct indicator to underground oil and gas reservoirs in surface oil and gas geochemical exploration. The hydrocarbon gas detected by acid-extraction method used at present in oil and gas geochemical exploration practice should be defined as "occluded hydrocarbon" instead of "adsorbed hydrocarbon", because this kind of hydrocarbon is combined with such media as soil grains. The surface anomaly of acid-extraction hydrocarbon is highly stable and has good repeatability, suggesting that the hydrocarbon migration process did occur during the geological history. Nevertheless, when used to reflect the information of deep oil and gas, the surface anomaly of acid-extraction hydrocarbon is subject to multi-interpretation. In view of this weakness of the acid-extraction method, a set of hydrocarbon desorption devices have been designed and developed, and a new extraction method and technique for soil adsorption hydrocarbon has been established. This newly developed hydrocarbon detecting technique can be used to collect the dynamic information of petroleum system at surface, intensify the study of hydrocarbon sources in the course of surface hydrocarbon measurement, and improve the prediction success ratio in surface oil and gas geochemical exploration practice.
