流体包裹体微量元素在油气勘探中的应用——以塔里木盆地塔中地区为例

摘要

Trace elements of oil-bearing fluid inclusion in sixteen Silurian oil-containing sandstones from ten wells in Tazhong area were performed by inductively coupled plasma mass spectroscopy（ICP-MS）,the distribution characteristics were analyzed,and their demonstrative geological significance were furthermore discussed.The results show that for the same sample,each trace element abundance is small to one order of magnitude,and large to hundreds orders of magnitude,but for the different samples,the difference times of the same element abundance is ordinarily lower than one order of magnitude,some element（Ni and Ti）may reach up to one order of magnitude or more.In the same well field,the abundance distribution of part trace elements of samples from different wells present preferable regularity,such as Ni,Fe,Al,Cu,Ti,Mg,Cr and so on,and the distribution rules of Ni,Cu and Ti show a certain similarity,whereas the distribution of Cr,Al,Mn and Mg are similar to each other.As a whole,the distribution rule of main trace elements is that the abundance is increasing from downstructure location to structural high.Of all the samples,the ratios of V/Ni is generally low,range from 0.044 to 0.683,most of samples are less than 0.5,lower V/Ni ratio and high Fe content represent a strong reductive depositional environment.Variation characteristics of the single trace elements,such as Ni,Cu,Αl and Ti,obviously disappear a noticeable rule and indicated that oil migrated from Well Tazhong 69 and Well Tazhong 15 to Well Tazhong 16 and Well Tazhong 161,namely Silurian hydrocarbons in Tazhong area migrated towards structural high or stratigraphic pinch out direction,from northwest to southeast on the plane,which also reflected by the trace element suite.Therefore,trace elements of oil-bearing fluid inclusion can provide effective evidence for studying oil and gas migratory direction.%采用电感耦合等离子体质谱（ICP-MS）测试分析技术,对塔中地区10口井16个志留系沥青砂岩包裹体微量元素进行了分析,探讨了包裹体微量元素分布特征及变化规律,并深入分析了其所指示的地质意义。结果表明,所测得的微量元素丰度差异明显,同一井区内或不同井区之间,各井主要的微量元素分布规律表现出从构造低部位向构造高部位方向,微量元素丰度总体上呈增大的趋势。较低的V/Ni比值和较高的Fe含量指示一种强还原的沉积环境;单个微量元素与微量元素组的变化规律表现出较好的一致性,反映出塔中志留系油气向构造高位置或地层尖灭方向的运移,在平面上从西北向东南方向运移。因此,包裹体微量元素在研究油气运移方向时可以提供有效的依据。