烃类成因对天然气水合物成藏的控制

天然气水合物具有能量密度高、分布广、规模大、埋藏浅、成藏物化条件优越等特点,是未来的新型海洋能源。模拟实验显示,在烃类气体供给充分,温度低于平衡温度、压力大于平衡压力的条件下,天然气水合物的形成对于烃类气体的来源没有选择性。然而,已经获取的天然气水合物样品的分析显示,形成水合物的气体大多数为微生物成因气体,只有少量为热解气。最新的研究显示,形成生物气的营养源丰富,适合微生物的地质条件宽泛,生物气能够为形成天然气水合物提供充足的气源。通过对热解气和生物气形成天然气水合物条件的研究,以及对天然气水合物的地质分布特征的分析,笔者强调指出,与热解气相比,生物气更易于形成天然气水合物,而热解气形成的天然气水合物实际上意味着资源的严重破坏,并进一步认为,南海天然气水合物勘探方向,应集中在有利生物气形成富集以及有利于水合物形成的地质条件的分析和地质体的调查上,而不是在常规的深部油气藏附近展开。

Gas origin constraint on the formation of gas hydrate

Although the experiment testified that there is no superiority among gas origins in the course of gas hydrate formation, the analyses on the samples acquired exhibited that biogases are the majority and thermolytical gases are the minority in the gases that formed gas hydrate. The latest re.search indicated that there are abundant nutrition sources for forming biogases and extensive geological environmem suitable to micro-organisms, therefore, it is sure that biogases can provide sufficient gases to form gas hydrate. By comparing the forming condition of these two different origin gases and by characteristic analysis of geological distribution of gas hydrate, the author emphasizes that biogases are much easier to form gas hydrate than thermolytical gases, and that the thermolytical gas hydrate signifies the re`source depletion instead of the re.source accumulation. Moreover, the author suggests that the exploration should not be carried out around the regular deep gas and oil, but focus on the survey of geological conditions prone to biogas formation and accumulation and to gas hydrate formation.