用正构烷烃分布特征鉴别海上混合原油

Identification of blend crude oils spilled on sea by distribution characteristics of n-Alkanes

为鉴别海上混合型溢油,对混合原油的正构烷烃分布特征进行探讨,通过混油实验考察混合比对正构烷烃分布以及诊断比值的影响.实验中正构烷烃分布相异最大的大庆原油和沙特原油混合后,n-C_(10)—n-C_(18)的相对含量与大庆原油比例呈线性负相关,而n-C_(18)—n-C_(35)与其呈线性正相关,这种双向分布的特点明显不同于单油的单向分布.正构烷烃分布相近的阿联酋-伊拉克混油中n-C_(10)—n-C_(35)分布与单油几乎相同,但其n-C_(18)/Ph随着混合比而变化,据此可以判别是混油还是单油.混合原油的n-C_(17)/Pr、n-C_(18)/Ph和Pr/Ph取决于单油之间的差异性,相差较大的混合后与混合比呈线性相关.30 d短期风化实验表明,混油中的n-C_(10)—n-C13受风化影响下降明显,而n-C15—n-C_(35)变化不大.混合原油的n-C_(17)/Pr、n-C_(18)/Ph和Pr/Ph基本上不受风化影响,即诊断比值仍可作为鉴别风化混油种类的依据.

Distribution characteristics of n-alkanes in blend crude oils were investigated to identify the types of oils spilled on sea. The influence of blend ratio on n-alkanes distribution and diagnostic ratio were investigated after crude oil mixing. For the blend oil of Daqing and Saudi Arabi which had the maximum difference in n-alkanes distribution, the relative content of n-C10-n-C18 negatively and linearly correlated with same proportion, but that of n-C18-n-C35 positively and linearly correlated with the proportion of Daqing. This means that the distribution of n-alkanes in blend curde oil is two-way and significantly different from one-way distribution of single crude oil. The distribution of n-C10-n-C35 in blend oil of UAE and Iraq was similar to each oil, but n-C18/Ph ratio changed with blend ratio, this feature could be used to distinguish single or blent oil in this case. n-C17/Pr, n-C18/Ph and Pr/Ph in blend oils depend on the dissimilarity of each oil, the diagnostic ratio linearly correlated with blend ratio after mixing with large dissimilarity. The short-term weathering experiments for 30 days showed that n-C10-n-C13 decreased significantly but n-C15-n-C35 changed little in blend oil. The diagnostic ratio of blend oil was almost unchanged by weathering, and can still be used for identification of blend oil species.