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古海洋数据表明,甲烷水合物在全球气候变化中起着重要的作用。然而,人们对全球气候变暖期间可能引起甲烷释放的机理却了解得甚少。尤其是在天然气水合物区域下面的游离气带的大小和作用,大都因为其游离气带的底界并不是一个相界,而相对来说并不受限制,所以也就无法进行系统描述。在本文中,我们评价了在上伏沉积物中,通过由断层滑动所引起的阀盖开关作用而使得连通游离气带的最大厚度在机制上得到调整的可能性。我们所得到的结果表明,临界天然气柱就存在于盆地环境中大多数天然气水合物区域的下面,这意味着上述这些区域就是引起机械断裂的原因,因此,对极端条件下的变化应予以高度重视。据估计,全球游离气储层中甲烷总量的61~23可能圈闭在水合物中。如果这些气藏沿被动大陆斜坡都是巨厚的,那么我们便可计算出,海底温度每增加5℃就会导致游离气带释放出约2000Gt的甲烷气,同时这也是在全球变暖过程中快速释放甲烷的机理。
Paleoclimate data show that methane hydrate plays an important role in global climate change. However, little is known about the mechanisms by which methane may be released during global warming. In particular, the size and effect of the free gas zone beneath the gas hydrate zone are largely unknown because the bottom boundary of the free gas zone is not a phase boundary but relatively unrestricted. In this paper, we evaluate the possibility of a mechanistic adjustment of the maximum thickness of the communicating free gas zone in the ascending sediment by the valve cover switch action caused by the sliding of the fault. The results we have obtained show that the critical natural gas column is present below most of the gas hydrate area in the basin environment, which means that these areas are the cause of mechanical failure and therefore should be given high priority for changes in extreme conditions . It is estimated that 61 to 23 of the total amount of methane in the global free gas reservoir may trap in hydrates. If these reservoirs are massive along the passive continental slope, then we can calculate that every 5 ° C increase in the seafloor would result in about 2000Gt of methane gas being released from the free gas zone, and this is also a factor in the global warming process Quick release of methane mechanism.