Non-Fickian diffusion and the accumulation of methane bubbles in deep-water sediments.
Non-Fickian diffusion and the accumulation of methane bubbles in deep-water sediments.
复制标题
深水沉积物中的非菲克扩散和甲烷气泡的积累。
DOI：
10.1140/epje/i2014-14045-x
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发表时间：
2014
期刊：
影响因子：
--
通讯作者：
Goldobin DS
中科院分区：
文献类型：
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作者：
Goldobin DS
摘要在没有裂缝的情况下，深水沉积物中的甲烷气泡可以通过表面张力被固定地捕获在多孔基质中。因此，气体物质转移的主要机制是气体分子在孔隙水中的扩散。为了准确地描述这一过程，需要考虑非费克扩散，包括热扩散和引力作用。我们估算了考虑非Fickian扩散的甲烷水相扩散通量，并预测在深水沉积物中存在广泛的气泡物质聚集区。揭示了水合物沉积能力的极限；太弱的沉积不能到达水合物稳定带的底部并形成任何泡状水平线。
AbstractIn the absence of fractures, methane bubbles in deep-water sediments can be immovably trapped within a porous matrix by surface tension. The dominant mechanism of transfer of gas mass therefore becomes the diffusion of gas molecules through porewater. The accurate description of this process requires non-Fickian diffusion to be accounted for, including both thermal diffusion and gravitational action. We evaluate the diffusive flux of aqueous methane considering non-Fickian diffusion and predict the existence of extensive bubble mass accumulation zones within deep-water sediments. The limitation on the hydrate deposit capacity is revealed; too weak deposits cannot reach the base of the hydrate stability zone and form any bubbly horizon.Graphical abstract