天然气水合物发现区和潜在区气源成因

为探讨天然气水合物发现区的气源成因，对ODP 204航次4个站位58个沉积物样品进行5个温度点的生气量模拟实验，对各温度点产生的气体进行同位素测定。测试结果显示，在低温阶段（25 ℃、35 ℃、45 ℃），甲烷的δ¹³C明显偏大，一般大于-40‰，显示出热解成因气的特征；而高温阶段（55 ℃）甲烷的δ¹³C为-75.5‰，显示出明显的生物成因气的特征。结合东沙海域天然气水合物潜在区气源成因的讨论，可以得出如下结论：天然气水合物的气源成因受控因素多，需要综合多种指标进行判别。

Gas Sources Genesis in the Gas Hydrate Discoveries and Potential Areas

In order to study the gas sources genesis in gas hydrate discoveries and potential areas,gas-generating amounts of 58 sediment samples from 4 sites of ODP 204 Expedition have been modeled by 5 temperature points,gas chromatography is used to test the isotope from different temperature points.The test results show that methane carbon isotope(δ13C)is evidently heavier among the lower temperature modeling points,commonly larger than-40‰,displaying the isotopic feature of thermogenic gas;while the lighter δ13C could reach to-75.5‰ when the modeling temperature is higher than 55 ℃,showing the isotopic feature of biogenic gas.Integrated with the discussion of gas genesis of Dongsha potential area,the conclusions could be drawn as follows,gas genesis could be controlled by many factors,and correct gas genesis could be got through the combination of other factors besides the methane carbon isotope.