Influences of water media on the hydrogen isotopic composition of natural gas/methane in the processes of gaseous hydrocarbon generation and evolution  

作　　者：WANG XiaoFeng LIU WenHui XU YongChang ZHENG JianJing 

机构地区：[1]Key Laboratory of Petroleum Resources Research, Institute of Geology and Geophysics, Chinese Academy of Sciences, Lanzhou 730000, China [2]Research Institute of Petroleum Exploration and Production, China Petroleum & Chemical Corporation, Beijing 100083, China

出　　处：《Science China Earth Sciences》2011年第9期1318-1325,共8页中国科学（地球科学英文版）

基　　金：supported jointly by National Natural Science Foundation of China (Grant No. 40703001) ;the "Western Doctors’ Project under the Western Light Program" sponsored by the Chinese Academy of Sciences

摘　　要：The influences of water media on the hydrogen isotopic composition of organic-thermogenic natural gas were tested in three series of experiments on coal pyrolysis, with no water, deionized water （δDH2O-58‰）, and seawater （δSDn2O=-4.8‰） added, respectively. The experimental results show that the productivities of H2 and CO2 obviously increased under hydrous conditions and that the productivity of CH4 also remarkably increased in the high-evolution phase of hydrous experiments. Water was involved in the chemical reaction of hydrocarbon generation, and then the hydrogen isotopic composition of methane was affected. There is a linear correlation between the hydrogen isotopic composition of methane and its productivity, as reflected in the three series of experiments. In the case of the same CH4 productivity, the hydrogen isotopic composition of the methane produced in anhydrous experiments was the heaviest, that of the methane produced in seawater-adding experiments came second, and that of the methane produced in deionized water-adding experiments was the ligbtest. The hydrogen isotopic composition of natural gas/methane is affected by the following factors： 1） the characteristics of hydrogen isotopic composition of organic matter in source rocks, 2） the thermal evolution extent of organic matter, and 3） fossil-water media in the natural gas-generation period. The experimental results show that the influence of the fossil-water medium in the natural gas-generation period was lower than that of the other factors.The influences of water media on the hydrogen isotopic composition of organic-thermogenic natural gas were tested in three series of experiments on coal pyrolysis, with no water, deionized water (δDH2O=?58‰), and seawater (δDH2O=?4.8‰) added, respectively. The experimental results show that the productivities of H2 and CO2 obviously increased under hydrous condi tions and that the productivity of CH4 also remarkably increased in the high-evolution phase of hydrous experiments. Water was involved in the chemical reaction of hydrocarbon generation, and then the hydrogen isotopic composition of methane was affected. There is a linear correlation between the hydrogen isotopic composition of methane and its productivity, as reflected in the three series of experiments. In the case of the same CH4 productivity, the hydrogen isotopic composition of the methane produced in anhydrous experiments was the heaviest, that of the methane produced in seawater-adding experiments came se cond, and that of the methane produced in deionized water-adding experiments was the lightest. The hydrogen isotopic com position of natural gas/methane is affected by the following factors: 1) the characteristics of hydrogen isotopic composition of organic matter in source rocks, 2) the thermal evolution extent of organic matter, and 3) fossil-water media in the natural gas-generation period. The experimental results show that the influence of the fossil-water medium in the natural gas-generation period was lower than that of the other factors.

关 键 词：water medium natural gas hydrogen isotopic composition pyrolytic simulation experiment 

分 类 号：P588.121[天文地球—岩石学] TM619[天文地球—地质学]