顶空悬滴液相微萃取技术在油气化探中的应用

Application of headspace single-drop microextraction( HS-SDME)technique in geochemical exploration for petroleum

油气化探的理论基础是地下油气藏中的烃类向上渗漏,在近地表形成一系列可被检测的有规律的地球化学响应,而油气化探通常以C1-C5烃类为检测对象。如果说土壤或沉积物中的C1-C4烃类还有可能是细菌作用形成的,那么C6-C12的烃组分则应该完全为热成因的。因此,检测土壤或海底沉积物中的C6-C12的烃组分,可以为油气藏预测提供最直接的证据。由于汽油烃组分在土壤和海底沉积物中含量低及检测手段和技术的缺乏,导致汽油烃组分在油气化探中很少被关注。以分析完罐顶气后的钻井岩屑液体为对象,采用顶空悬滴液相微萃取技术(HS-SDME),对某钻井中不同深度的汽油烃(C6-C12)组分进行定量分析。研究结果显示,通过HS-SDME法可以很好地检测钻井岩屑液体中的汽油烃组分,且利用这些汽油烃组分含量判别的钻井油气储层深度与实际储层深度一致,表明HS-SDME法可用于井中化探及地表油气化探。

All surface geochemical exploration methods for oil and gas are based on the theory that hydrocarbons generated and trapped at depth seep in varying but detectable quantities to the surface,and the main components detected are usually C1- C5 hydrocarbons. The C1- C4 hydrocarbons could come from degradation of organic matter by microbial organisms,while the gasoline range hydrocarbons are totally sourced from thermogenic processes. Therefore,the detection of gasoline range hydrocarbons in soils or sediments could be the most direct evidence for hydrocarbon seepage and the method used to detect the C6- C12 range hydrocarbons could be a useful technique for surface geochemical exploration method for petroleum. However,because the concentration of gasoline range hydrocarbons in the soils or sediments are usually very low,and the present techniques for detecting those hydrocarbons are not adequate,the gasoline range hydrocarbons have seldom been used in surface geochemical exploration for oil and gas. In this study,the headspace single-drop microextraction（ HS-SDME） technique coupled with gas chromatography-flame ionization detection（ GC-FID） was employed to determine C6- C12 gasoline range hydrocarbons in well drilling mud sample. The results show that the C6- C12 hydrocarbons in the samples could be detected by HS-SDME,and the reservoir depth determined by the concentration of C6- C12 hydrocarbons was the same with the actual petroleum reservoir depth,which indicated further that the HS-SDME method could be used in geochemical exploration for petroleum.