Eur. Phys. J. E (2014) 37: 45
https://doi.org/10.1140/epje/i2014-14045-x

Regular Article

Non-Fickian diffusion and the accumulation of methane bubbles in deep-water sediments

¹ Department of Mathematics, University of Leicester, LE1 7RH, Leicester, UK
² Department of Geology, University of Leicester, LE1 7RH, Leicester, UK
³ Institute of Continuous Media Mechanics, UB RAS, 614013, Perm, Russia
⁴ British Geological Survey, NG12 5GG, Nottingham, UK
⁵ School of Earth and Environment, University of Leeds, LS2 9JT, Leeds, UK

^* e-mail: Denis.Goldobin@gmail.com

Received: 26 December 2013
Revised: 13 April 2014
Accepted: 30 April 2014
Published online: 30 May 2014

Abstract

In 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.