Effect of seafloor temperature and pressure variations on methane flux from a gas hydrate layer: Comparison between current and late Paleocene climate conditions

Abstract

Abstract. We investigate the response of a methane hydrate layer in marine sediments to cyclic seafloor perturbations of temperature and pressure in order to determine the change in seafloor methane flux resulting from gas hydrate dissociation or accumulation. By using a one-dimensional model describing mass, energy, and methane transport through porous sediments we show that seafloor pressure changes have negligible effect on methane transport to the seafloor. The effect of seafloor temperature perturbations is more pronounced than that of pressure. With an initial seafloor temperature of 3øC, which corresponds to current conditions on Earth, a + 4øC seafloor temperature perturbation occurring over 104 years does The principal point is that strong coupling between methane transport and seafloor temperature occurs because significant hydrate accumulation and dissociation take place near the seafloor only when the seafloor temperature is relatively high. This was the case during the late Paleocene, but it is not the case at present.

Methane hydrate stability and anthropogenic climate change

“…Methane can reach the atmosphere if the methane bubbles are released in waters that are only a few tens of meters deep, as in the case of melting ice complex permafrost off Siberia (Xu et al, 2001;Shakhova et al, 2005;Washburn et al, 2005) or during time periods of lower sea level (Luyendyk et al, 2005). If the rate of methane release is large enough, the rising column of seawater in contact with the bubbles may saturate with methane, or the bubbles can be larger, potentially increasing the escape efficiency to the atmosphere.…”

Flow response of a segregating mixture by interacting lattice gas simulation

“…Our main interest, however, is focused on understanding the flow of a mixture of methane gas along with other components (i.e., immiscible hydrocarbon) below the ocean floor to sub-bottom area in aqueous and dynamic sedimentary environment [2][3][4][5]. In the long term, we are interested in a comprehensive understanding of the effects of driving fields such as concentration gradients, hydrostatic pressure, thermal gradient, etc.…”

Eruptive flow response in a multi-component driven system by an interacting lattice gas simulation

“…How can structural evolution and the flow rate respond to an external hydrostatic pressure bias? As pointed out above, understanding such basic questions is essential in context to the flow of methane gas, hydrocarbon, their complex compounds, and hydrate formation and its dissociation below the ocean floor [9][10][11][12][13]. Using an interacting lattice gas model, we have studied [42] the onset of segregation and partial layering in a steady-state flow of an immiscible mixture.…”

“…), mixtures of fluids, and gas [1][2][3][4][5][6][7]. The response of these constituents to temperature, pressure, and concentration gradients lead to a variety of correlated, local and global phenomena involving flow, extrusion, evolution, and settling of constituents with a range of relaxation time and length scales [4,[8][9][10]. Understanding of structure and dynamics may involve unsteady and steady-state mechanism which are equilibrium and far from equilibrium processes.…”

“…Pandey). sedimentary compounds has attracted a considerable interest in marine geosciences [9][10][11][12][13]. Of our particular interest are the effects of driving fields such as concentration gradients, hydrostatic pressure, thermal gradient, etc.…”