?????????????????????????????

介绍了游离烃技术方法，该方法通过抽取土壤中气体，检测其中与油气微渗漏有关的烃类组分，确定油气化探异常。研究了游离烃组分的浓度分布特征，揭示出烷烃中甲烷(以YC₁表示)是独立因子，加之其浓度分布分异性好，证明了YC₁中储存与油气有关的信息，具有重要的化探意义。通过游离烃组分与其它化探指标关系的分析研究，得出了与其它化探指标不相关的认识，证明游离烃在其它化探指标中是独立因子，指出其具有独立的化探意义。最后阐述了其化探意义表现的3个方面：已知区验证效果良好；应用地域广阔，不仅适用于北方碱性土壤区，更适用于南方酸性土壤区；YC₁的δ13C₁具有良好的应用前景。

PETROLEUM GEOCHEMICAL EXPLORATION SIGNIFICANCE OF SOIL FREE HYDROCARBON TECHNIQUE

The free hydrocarbon technique by detecting the oil/gas microfiltration related hydrocarbon compenents in the gas aspirated from soil and by determining the petroleum geochemical exploration anomalies is introduced in the paper.Through investigating the concentration distribution features of free hydrocarbon component,it was revealed that YC１ is an independent factor with good concentration distribution differential property and proved that some messages relevant to oil/gas are stored in the YC１,which is of important geochemical exploration significance.In light of analyzing and studying the relations between the free hydrocarbon component and the other geochemical exploration indexes,it was pointed that the free hydrocarbon component is an independent factor which has distinctive geochemical exploration significance,being uncorrelated to the other geochemical exploration indexes.Its geochemical exploration significance include three aspects,i.e.the effectiveness examined at the known hydrocarbon bearing area was good;the region of its being applied is vast,being suitable not only for the alkline soil in the north but also for the acid soil in the south;and the δ１３Ｃ１,of ＹＣ１ is of a fair application prospect.