RELATIONS BETWEEN THE LIGHT-HYDROCARBON INDICATORS IN PETROLEUM GEOCHEMICAL EXPLORATION AND THE SURFACE EXPRESSIONS OF HYDROCARBON MIGRATION

Hydrocarbon gases exist in the forms of free gas,adsorbed gas,dessolved gas and gas-liquid inclusion in surface.Petroleum geochemical prospecting in Gujiazi and Houwujiahu gas field areas in the Shiwu Fault Depression in Southeastern Songliao Basin shows that the indicators of acid-digestion hydrocarbon,heat-release hydrocarbon and head-space gas are not correlative with each other.This means the hydrocarbons have different sources.The indicators of acid-digestion hydrocarbon,heat-release hydrocarbon and head-space gas contain abundant oil and gas information.The anomaly distributions of these hydrocarbon indicators are corresponding with the structures and gas fields in the study area.The correlation between gas field and surface hydrocarbon anomaly shows that it is the hydrocarbon vertically migrating to the surface from deep oil and gas accumulation that bring the hydrocarbon anomalies into existence in the surface.