The Study On The Distribution Change Of N-Alkanes In Blend Crude Oil

With the acceleration of modern industrialization, accidents of oil spill continue to occur, which has become one of the main pollution in the marine environment. Most of the oil spill is dominated by single species, while the other is blend oil species, and this gives the relevant law enforcement brings lots of difficulties for ruling the liability of oil spill accidents. Currently, many studies on the identification of oil spill mostly focus on the characteristics of single crude oil, while the study on the characteristics of blend crude oil is extremely rare. Therefore, this problem was attempted to solve in this study. The characteristics of distribution change of n-alkanes in blend crude oil were discussed in order to provide a technical support for the identification of oil spill.Five kinds of crude oil samples from Saudi Arabia, UAE, Iraq, Malaysia and Daqing were collected, and GC-FID method was used to detect and analyze the n-alkanes in the oil samples. According to the principal components analysis of n-alkanes and the ratio of Ni to V of five single crude oil, four groups of oil samples were blended and regarded as samples before weathering. The influence of blending ratio on the change of relative content of n-alkanes and the characteristics of n-C17/Pr、 n-C18/Pr、Pr/Ph were investigated. On this basis, a group of Daqing-Saudi Arabia in which n-alkanes distributions are different and a group of UAE-Iraq in which n-alkanes distributions are similar were selected for30days weathering experiments, the influence of weathering on n-alkanes and n-C17/Pr、n-C18/Ph、Pr/Ph in different blend ratios were discussed.A group of Daqing-Saudi Arabia: The distribution change of n-alkanes was significant with the change of blend ratio. The relative contents of n-C10～n-C18was negatively and linearly correlated with the proportion of Daqing crude oil, and the linearity equation as y=-0.2684x+59.338(r=0.9494). The relative contents of n-C18～n-C35was positively and linearly correlated with the proportion of Daqing crude oil, and the linearity equation as y=0.2643x+46.283(r=0.9474). n-C17/Pr and Pr/Ph of Daqing and Saudi Arabi crude oil were similar, so they almost did not change and were not affected by the blend ratio in blend oil. However, n-C18/Ph which was different between two crude oil was linearly correlated with blend ratio. After weathering for30days, the relative contents of n-C10～n-C13declined obviously. n-C17/Pr、n-C18/Ph and Pr/Ph are related with blend ratio, but hardly affected by weathering.A group of UAE-Iraq: Because the distributions of n-alkanes in UAE and Iraq crude oil were almost the same, the distribution of n-alkanes of UAE-Iraq in different blend ratios was still quite similar. n-C17/Pr and Pr/Ph of UAE and Iraq crude oil were similar, so they almost did not change. But n-C18/Ph which was different between two crude oils was linearly correlated with blend ratio. After weathering for30days, the relative content of n-C10～n-C１3declined obviously. n-C17/Pr、n-C18/Ph and Pr/Ph are related with blend ratio, but hardly affected by weathering.