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采集了世界各地的水下天然气水合物样品并分析了其中烃类气体成分和甲烷碳同位素组成后认为,进入水晶格结构中的甲烷分子主要是微生物还原沉积有机质的CO_2而产生的。典型的测试结果为:甲烷含量占烃类气体总量的99％以上;甲烷碳同位素组成(δ~(13)C PDB)范围在-57‰～-73‰。仅在墨西哥湾和里海两处发现了主要由热成因甲烷形成的天然气水合物,烃类气体中甲烷含量为21％～97％,甲烷碳同位素值为-29‰～-57‰。少数地区天然气水合物中的甲烷为混合成因,以微生物成因的甲烷为主。在阿拉斯加和俄罗斯的陆上气体水合物中,甲烷含量亦大于烃类气体总量的99％,碳同位素组成则为-41‰～-49‰,这种甲烷也属混合成因,但似乎以热成因的甲烷为主。
After collecting samples of underwater gas hydrates from all over the world and analyzing the composition of hydrocarbon gas components and methane carbon isotopes, it is considered that the methane molecules entering the crystal lattices of the crystal structure are mainly produced by microbial reduction of CO 2 from the deposited organic matter. Typical test results are as follows: the methane content accounts for more than 99% of the total amount of hydrocarbon gases; the carbon isotope composition (δ ~ (13) C PDB) of methane ranges from -57 ‰ to -73 ‰. Gas hydrates mainly formed of pyrogenic methane are found in the Gulf of Mexico and the Caspian Sea, with methane content of 21% -97% and methane carbon isotope of -29 ‰ ~ -57 ‰. Methane in a few areas of natural gas hydrate is a mixed cause, mainly due to microbial methane. In continental gas hydrates in Alaska and Russia, the methane content is also greater than 99% of the total hydrocarbon gas and the carbon isotope composition is -41 ‰ ~ -49 ‰, which is also a mixed cause, but seems to be mixed with heat Genesis of methane-based.