Abstract: Geochemical exploration is one of geological prospecting method for oil and gas.An important role has been played by such a technique in finding oil and gas over years.The presence of trace amount of light hydrocarbons in surface soil or in ground water,however,are either the micro-seepage from subfurface hydrocarbon accumulations or other sources due to photodecomposition of organic matters and microorganism activities.This paper gives a discussion on the screening out of significant information from surface geochemical data based on a comprehensive study and computer processing of the data as well as improvement of sampling methods in order to enhance the successful ratio in predicting the potential hydrocarbon deposits.