原油中微量元素地球化学特征

GEOCHEMISTRY OF TRACE ELEMENTS IN CRUDE OILS

利用原油中微量元素的分布，可以明显地将陆相原油和海相原油区分开，结合原油的硫含量，可以初步判断油源岩沉积环境和岩性。利用原油稀土元素配分模式可以进行油／油对比，稀土元素分馏特征反映原油运移效应，Ｅｕ异常反映油源岩沉积时的相对氧化－还原条件。本文根据塔里木盆地原油中微量元素的地球化学特征，区分了陆相、海相原油，源于石炭系的原油接近于陆相原油。

In the article, the geochemical features of trace elements in crude oils are mainly discussed. Based on the ratios of Ca/Ni,Mg/Ni, Cu/Ni, Zn/Ni, Sr/Ni, Ba/Ni, V/Ni and Ph/Ni, oils can be divided into 3 groups in Tarim basin. V, Cu, Cr and Sr are generally rich in marine oils, and Ni is very rich in nonmarine oils. We can also get oil groups and determine depositional environments of source rocks by V-Ni fractions and sulfur contents in the oils. For example, the values of V/(V+Ni) are generally less than 0. 10 in nonmarine oils, in marine oils they change from 0. 10 to 0. 90 and sulfur contents are less than 1. 0%. Furthermore, by using V/Ni values, we can find out where the oil comes from. The oil-oil correlation can be carried out based on the distribution patterns of rare earth elements. By using the ∑REE, oils can be divided into three groups. The depositional environments of source rocks could be reflected by the Eu anomalous values, and petroleum migration can be discussed through the fractionation of rare earth elements.