天然气中硫化氢含量及硫同位素联测方法

Combined measurement of hydrogen sulfide content and sulfur isotope in natural gas

杨华敏 王萍 陶成 王杰 马亮帮

YANG Huamin WANG Ping TAO Cheng WANG Jie MA Liangbang

1. 中国石化 石油勘探开发研究院 无锡石油地质研究所, 江苏 无锡 214126; 2. 中国石化 油气成藏重点实验室, 江苏 无锡 214126

1. Wuxi Research Institute of Petroleum Geology, SINOPEC, Wuxi, Jiangsu 214126, China; 2. SINOPEC Key Laboratory of Petroleum Accumulation Mechanisms, Wuxi, Jiangsu 214126, China

我国含硫化氢天然气勘探潜力巨大，硫化氢成因、来源、形成机制为石油工作者所关注。硫化氢含量及硫同位素是两项常用且重要的判识指标。因硫化氢的强毒性，国内很多实验室较少检测或取消了此类检测项目。通过前处理流程优选硫化氢转化试剂，同时通过改进同位素质谱仪配套设备——调试硫同位素法拉第杯离子束聚焦等参数，安装特制色谱柱、特氟龙管路、硫反应管等，搭建了硫化氢含量及硫同位素联测技术平台；其次将高纯二氧化硫标准气替换为低浓度、低压力、小体积的工作标准气，通过系统条件实验探索(稳定性，标样分析等)，确定最优实验条件；最后将反应生成的固体沉淀物送入质谱仪中进行硫同位素组成信息的检测，通过与标准纯含硫物质同位素组成的信号对比，计算出待测气体中硫化氢含量。用该方法对鄂尔多斯盆地大牛地气田、富县气田、鄂西渝东红星地区部分含硫化氢天然气进行硫化氢含量和硫同位素测试，所测结果稳定、精度良好，同时与外部实验室比对结果吻合。与传统方法比，该方法一次进样可得到硫含量和硫同位素数值；优选醋酸银试剂一步化学法一次性转化，减少同位素分馏；另一方面将硫化氢转化为固态硫化银，与标准物质硫化银硫同位素直接对比，同位素溯源结果更具可靠性；以低浓度、低压力、小体积的二氧化硫作为工作标准气，降低了实验室安全风险和仪器损害，满足环保安全需求。

The natural gas containing hydrogen sulfide in China has great exploration potential, and the origin, source and formation mechanism of hydrogen sulfide are of concern to petroleum workers. Hydrogen sulfide content and sulfur isotope analysis are two common and important identification indicators. Due to strong toxicity of hydrogen sulfide, many laboratories in China conduct fewer tests or cancel such testing items. In this paper, hydrogen sulfide conversion reagent is preferring selected in pretreatment process. At the same time, through improving isotope mass spectrometer supporting equipment, i.e. tuning the parameters of ion beam focusing of sulfur isotope Faraday cup, installing special chromatography column, Teflon pipeline, sulfur reaction tube, etc., the technology platform for combined measurement of hydrogen sulfide content and sulfur isotope is constructed. Secondly, the high purity sulfur dioxide standard gas is replaced with working standard gas of low concentration, low pressure and small volume, and the optimal experimental conditions are determined through system condition experimental exploration (stability, standard substance analysis, etc.). Finally, the solid precipitate generated by the reaction was sent into the mass spectrometer for the detection of sulfur isotope composition information, and the concentration of hydrogen sulfide in the gas to be measured is calculated by comparing signal with the isotopic composition of standard pure sulfur-containing substances. By using this method, the hydrogen sulfide content and sulfur isotope in some natural gas of Daniudi and Fuxian gas fields in Ordos Basin, and Hongxing area in western Hubei and eastern Chongqing are measured. The measured results are stable with good precision, and are consistent with the results of external laboratories. Comparing traditional method, this method can obtain sulfur content and sulfur isotope values by a single sampling. The preferred silver acetate reagent with one-step chemical method can reduce isotopic fractionation. In addition, the hydrogen sulfide inverting into solid silver sulfide are more reliable directly compared with the standard substance silver sulfide isotope. With low concentration, low pressure, small volume SO2 as the working standard gas, it reduces the laboratory safety risk and instrument damage, and meets the environmental safety requirements.

国家自然科学基金面上项目(42273015)和中国石化油田部先导项目(YTBXD-FCZY-2023-1-07-003)联合资助。

https://doi.org/10.11781/sysydz202401166