天然气中SF_6等多种氟化物气体示踪剂的气相色谱检测

Detection of fluoride gas tracers in natural gas by gas chromatography

为了监测气驱油藏中的气体示踪剂,利用GC/ECD建立了一种分析天然气中多种氟化物气体示踪剂的方法。该方法选用GDX-104色谱柱,排除了样品中空气峰对检测的干扰,通过正交试验优化最低灵敏度组分的检测条件,并以此作为同时检测天然气或空气中多种气体示踪剂(SF_6、CF_2Br_2和C_4F_8)的条件,其中SF6、CF_2Br_2和C_4F_8的检出限分别为1×10^(-6)、1×10^(-5)和1×10^(-3)μg/L,重复进样7次的相对标准偏差不大于7%。通过对中原油田天然气驱油藏的气体示踪剂的监测,得到了示踪剂的产出曲线,弄清了该区块的非均质性和注采井的连通关系。该检测方法快速、简便,所需样品量少,可实现多种示踪剂同时检测,不仅适用于天然气中微量气体示踪检测,而且适用于大气环流的微量气体示踪检测。

In order to monitor the gas tracers in gas flooding reservoirs,a method for analyzing several fluoride gas tracers in natural gas by GC / ECD is proposed. GDX-104 chromatographic column is used in the analysis method,which eliminates the interference of the air peak in the sample to the detection results. The testing conditions of the fluoride gas tracer with the lowest sensitivity are obtained by orthogonal experiments,and they are as the conditions for detecting several gas tracers( sulfur hexafluoride,two fluorine dibromomethane and eight fluorine cyclobutane) in air or natural gas at the same time. The detection limit of SF_6,CF_2Br_2 and C_4F_8is 1 × 10- 6,1 ×10- 5and 1 × 10- 3μg/L respectively,the relative standard deviation of 7 samples is not more than 7%. The gas tracer output curves of the gas flooding reservoirs in Zhongyuan oilfield are obtained using the analysis method,and the heterogeneity of the reservoir and the connectivity between gas injection wells and production wells in the block are clarified. This fluoride gas tracer detection method is fast and simple,and can be used to detect many kinds of tracers at the same time,which is suitable for the detection of trace gases not only in natural gas but also in atmospheric circulation.