During a mass and energy exchange between the light hydrocarbon in reservoirs and its environment

a dynamic equilibrium is formed by the light hydrocarbons of all states under the action of sediment surface.The light hydrocarbon physically absorbed by surface soil mainly comes from the reservoirs below and their composition and content can reflect the nature and features of the associated reservoirs.By tracing the composition and content of absorbed light hydrocarbons

the hydrocarbon source(i.e.reservoir)can be located and its quality and characteristics can be predicted.The technology of physical absorption of light hydrocarbon is to completely release the physically absorbed light hydrocarbons from soil samples in a vacuum state and qualitative and quantificational analyse the composition of released hydrocarbon with a gas-chromatogram

so as to predict the quality and characteristics of the reservoir through an observation of the concentration change.The application of the technology in the pilots in Xinchang gas field of Sichuan basin

in Zhenyuan-Jinchuan loess tableland of Ordos basin

and in Chaiwopu Gobi of Tarim basin both with complex surface and geologic conditions gains positive resuits and implies a bright future for its further application and development.