气田水对甲烷氢同位素分馏作用  

The effect of gas field water on hydrogen isotope fractionation of methane

作　　者：秦胜飞[1] 周国晓 Qin Sheng-fei,Zhou Guo-xiao(PetroChina Research Institute of Petroleum Exploration ＆ Development ,Beijing 100083,China)

机构地区：[1]中国石油勘探开发研究院,北京100083

出　　处：《天然气地球科学》2018年第3期311-316,共6页Natural Gas Geoscience

基　　金：国家自然科学基金项目(编号:41372150);中国石油天然气股份有限公司科技项目(编号:2014B-0608);中国石油勘探开发研究院科技创新项目(编号:2012Y-001)联合资助

摘　　要：水对甲烷碳同位素有明显的分馏作用,但对甲烷氢同位素是否也有分馏作用目前还未见报道。采用自然脱气和真空水浴加热脱气的方法对四川盆地安岳大气田龙王庙组气藏中的气田水进行分步脱气,开展水溶气与游离气中甲烷氢同位素对比研究。发现气田水中脱出的甲烷氢同位素值比游离气的明显偏高。分步脱气研究表明,先后脱出的甲烷氢同位素有依次增高的趋势,说明气田水对甲烷氢同位素组成有明显的分馏作用。由此推断,在气藏形成过程中如果经历了大幅度的构造抬升,就会有较多的天然气从水中释放出来混入到游离气中,会使气藏中的甲烷氢同位素值增高。Water has obvious fractionation on carbon isotope composition of methane, but there is little study on the hydrogen isotope fractionation of methane caused by water.By means of the method of natural degassing and vacuum water heating degassing, step by step degasification on gas field water from Long-wangmiao gas reservoir of Anyue Gasfield in Sichuan Basin was carried out in this paper.Comparative stud ies were also carried out on hydrogen isotope between water-soluble methane and free gas.It is found that the hydrogen isotope of methane from the gas field water is obviously less negative than that of free gas. Step by step degassing studies show that the hydrogen isotopic value of methane got from gas field water became less and less negative.It indicates that the gas field water has obvious fractionation on methane hydrogen isotope composition.In the process of gas accumulation,if the reservoir experienced significant tectonic uplift, much natural gas released from the water will become free gas, so that the hydrogen isotopic composition of methane in the gas reservoir will become less negative.

关 键 词：气田水 水溶气 甲烷 氢同位素 分馏 

分 类 号：TE122.113[石油与天然气工程—油气勘探]