Methane Transport and Hydrate Formation

If methane, either from biogenic or thermogenic sources, is present in high enough concentration to stabilize the hydrate structure at thermodynamically favourable conditions (Figs. 14.3 and 

Hydrate Formation by in situ Biogenic Methane Generation and Transport in Advecting Fluids 

The amount of biogenic methane is essentially controlled by both the availability and reactivity of organic matter in the upper hundreds of meters of the sedimentary sequence. Davie and Buffett (2001, 2003) demonstrated the critical need for quantitative models of biogenic methane production to describe the distribution of gas hydrate in the top few hundred meters of sediment. Key parameters are rates of sedimentation, quality and quantity of the organic matter and biological activity rates. They show that hydrate accumulation from in situ production in sediment with a TOC of 1.5%, will be less than 7% of the pore volume 

Davie and Buffett (2001) also show that both in situ methane production and transport in upward migrating saturated fluids are needed to explain the dissolved chloride profiles observed 

Another driving force for methane transport is the generation of critical pressures in the gas phase (Flemings et al. 2003 Trehu et al. 2004). Interconnection of gas-filled pores below the GHSZ transmits hydrostatic pressures from greater depths because of the low density of the gas phase. The excess (non-hydrostatic) pressure at the top of the gas layer may be sufficient to 

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