应用显微激光拉曼光谱测定CO_2气体碳同位素值δ^(13)C的定量方法研究  

Quantitative Approach to Determination of δ^(13)C Value of CO_2 with Micro-Laser Raman Spectroscopy

作　　者：李佳佳[1] 李荣西[1] 董会[2] 王志海[2] 赵帮胜 程敬华[1] 

机构地区：[1]长安大学地球科学与资源学院,陕西西安710054 [2]中国地质调查局西安地质调查中心,陕西西安710054

出　　处：《光谱学与光谱分析》2017年第4期1139-1144,共6页Spectroscopy and Spectral Analysis

基　　金：国家自然科学基金项目(41173055);中央高校基金项目(310827165015)资助

摘　　要：单个流体包裹体同位素在研究岩矿古流体成因、矿床、油气和大地构造演化动力学等多个领域具有十分重要的意义,激光拉曼光谱是一项可以分析单个流体包裹体同位素的有效方法。本文提出应用显微激光拉曼光谱法来计算CO_2气体碳同位素值δ^(13)C。利用自行设计的装置将^(12)CO_2和^(13)CO_2按比例分别与N2混合,对混合气体样品进行显微激光拉曼测试分析后确定^(12)CO_2和^(13)CO_2的拉曼参数,这为用激光拉曼分析碳同位素值δ^(13)C奠定了理论基础。通过对不同比例的^(12)CO_2/^(13)CO_2人工合成CO_2包裹体样品和胜利油田CO_2天然气藏样品进行激光拉曼光谱分析,发现CO_2气体碳同位素摩尔分数比N_(13)/N_(12)与拉曼参数之间存在数学关系式,由此建立了根据碳同位素计算公式δ^(13)C=[(C_(13)/C_(12))_(样品)/(C_(13)/C_(12))_(标准)-1]×1 000‰,用激光拉曼分析获得的CO_2气体有关激光拉曼参数来计算δ^(13)C值的方法。按照该方法,应用显微激光拉曼光谱对胜利油田CO_2天然气藏样品分析计算其δ^(13)C值为-5.318‰,与用质谱仪分析测出的δ^(13)C值(-5.6‰)比较,其相对误差较小(≈5%),可以初步建立起应用显微激光拉曼光谱测定CO_2气体碳同位素值δ^(13)C的定量方法。Abstract Stable isotope of individual fluid inclusion has great significance in researching the formation of rock and mineral paleofluid, geology of ore deposits, oil/gas mineral deposits and geodynamics of tectonic evolutioru Micro-Laser Raman analysis is a method for stable isotopes in single fluid inclusions. This study proposed a method to calculate δ13C value with Micro-Laser Ra- man spectroscopy. 12 CO2 and la CO2 mixed with N2 at various molar fraction ratios respectively through self-devised experimental apparatus. The determination of Raman parameters provides theoretical basis for calculating the δ13 C value. Based on the study of principles and feasibility of the method of laser Raman spectroscopy, a series of known molar fractions of 12 CO2/la CO2 binary mixtures as artificial CO2 fluid inclusions have been prepared. The artificial CO2 fluid inclusions and CO2 gas from Shengli Oil- field have been analyzed with Micro-Laser Raman analysis method. And the molar fraction ratio Nla/N12 is related to Raman parameters, the value of δ13C could be calculated by formula δ13 C= [-（C13/C12 ）sample/（C13/C12 ）PDB--1]× 1 000δ. The δ13C value of CO2 gas from Shengli Oibfield is -- 5.6‰ and -- 5. 318‰ by using mass spectrometry and Micro-Laser Raman analysis method, respectively. The results demonstrate that it builds up a way to determine δ13 C Value of CO2 with Micro-Laser Raman Spectroscopy.

关 键 词：δ13C值 显微激光拉曼光谱 拉曼参数 流体包裹体 CO2气藏 

分 类 号：O657.3[理学—分析化学]