By using synthetic assessment and interpretation of downhole geochemical exploration

this paper proposed following methods such as the analogy-foil method of both key horizon and marker horizon which could be used to check the effectiveness of geochemical exploration index; the probability analysis for oil and gas reservoir prospercting; the method to analyse hydrocarbon superimposition intensity and the density gradient of hydrocarbon gas; Paxle graphic method for hydrocarbon-bearing formation evaluationl triangular diagram;light alkane ratio;D-function analysis.According to the methods mentioned above

the model of geochemical exploration anomoly for hydrocarbon generation and reservoiring was established in this paper.