Quantitative discrimination of hydrocarbon micro-seepage pattern

Studies of hydrocarbon micro-seepage have indicated that,when reservoir has been formed,oil and gas mainly seep as micro-bubble or with water.Based on isopachous stratigraphic model,a quantitative discrimination coefficient of micro-seepage pattern has been proposed and calculated according to general geological theory.It has been concluded that,1) Due to the changes of geological conditions,the micro-seepage pattern of hydrocarbon in strata is also changing;2) Hydrocarbon usually seeps as micro-bubbles and transfers to water-soluble pattern as it comes closer to earth surface.The 2 pa-tterns result in hydrocarbon abnormality on earth surface while diffusion only forms background field;3) Sealing ability of direct seal,stratigraphic physical property and vertical movable water content are the key factors controlling hydrocarbon micro-seepage pattern.Proposal of the discrimination coefficient is significant for micro-seepage mechanism research.It also settled a foundation for numerical simulation,formation interpretation and evaluation of geochemical field in hydrocarbon chemical exploration.