The mercury vapour shows clearly a good similarity to gases derived from oil and gas fields in aspect of their migration and accumulation.Therefore

its existence in these gases is not only related to the nature of the.crude oil

but also depends on the geological setting.The mercury vapour generally has relatively high penetrative ability and it can constitutean anomalous distribution in soil

while moving upwards from oil-gas reser-voir and arriving at the earth surface.Systematic measurements of mercury vapour were carried out in 1979 over two oil fields in the Biyang basin

after a test analysis of the geochemical features of mercury vapour overvarious places of Huabei

northern Jiangshu and Jianghan basins

and it isproven that there ate indeed mercury anomalies which exist over oil fields.Thus

this can be used as a new parameter for the oil and gas prospecting.A correlative analysis of data available reveals further that thecontent of mercury in natural gases is in function with some factor srelevent to oil productive horizons.A predominent detection conforms thatthe content of mercury vapour has apparently a positive relationship with temporature

depth and static pressure of oil productive horizons

but negativere lationship with gas/oil ratio and quantity of waters in crude oil.