EXPERIMENTAL STUDY ON TRACE ELEMENT METHOD IN SURFACE GEOCHEMICAL PROSPECTING FOR OIL AND GAS

Based on confirming the existence of hydrocarbon microseepage over Xinchang gas field in west of Sichuan Basin,surface trace element survey and hydrocarbon geochemical exploration were conducted in this area.The relationship between trace elements and surface geochemical indicators with hydrocarbon microseepage were studied.Some trace elements were proved to have stability and indicative significance to oil and gas by comparing the new data with previous ones.According to multivariate statistics and combining with the effects of microseep anomaly reflected by trace elements in surface soil over the known gas field,it is thought that trace element indicators Cl,S,V,Ni,Cu,Zn,Sb,Cr,Co,Ba,Mo,Mn,Fe,Fe/Mn and V/Ni are effective for gas-prospect evaluation in this area because of the respondence to the gas field.Moreover,the geologic significance of the characteristics of trace elements anomaly was discussed.The effective indicators optimized in the known gas field are of certain directive significance and important immediate significance to perspective assessment of oil and gas in large area for the future.