Pore space hydrate formation in a glass bead sample from methane dissolved in water

Abstract

[1] An experimental device designed and developed to grow methane hydrate in the pore space of a sediment was successfully used with a glass bead sample. The underlying idea for the experiment is that methane dissolved in water is transported with upward moving fluids from its place of origin at greater depths to formations within the hydrate stability field where the methane is removed from the pore water to form hydrate. This process is simulated in a closed loop flow system where methane charged water from a gas/ water reservoir outside the hydrate stability field is pumped into the sediment sample cell in the stability field for methane hydrate. The fluid depleted of methane, then flows back into the gas/water reservoir to be recharged with methane. When the experiment was terminated due to blockage of flow by hydrate formation, hydrate saturation was about 95%. Citation: Spangenberg, E., J. Kulenkampff, R. Naumann, and J. Erzinger (2005), Pore space hydrate formation in a glass bead sample from methane dissolved in water, Geophys.

Are Laboratory-Formed Hydrate-Bearing Systems Analogous to Those in Nature?

“…Experimental System and Hydrate Formation Procedure. A major drawback of the experimental system used for the generation of hydrate bearing samples in the studies of 2005 to 2007 15,47 was the small sample size. The sediment sample cell of this system was 50 mm in both diameter and length.…”

“…Because methane solubility is low, hydrate formation from dissolved-phase methane in the laboratory is a slow and long-lasting process. 15,52,53 However, because it is assumed that this process forms the high hydrate concentrations in sands and coarse silts, 31,20 the method should be improved in order to provide information and data that are valuable for the interpretation of geophysical field and borehole measurements and the general understanding of this type of hydrate-bearing reservoirs. This formation process corresponds to scenario 1.…”

“…From the corresponding electrical conductivity increase of withdrawn fluid samples, the amount of water fixed in the hydrate structure and the overall hydrate saturation can be determined. 15,22 The pore pressure is kept constant by a continuous methane supply from the methane cylinder via the methane pump.…”

“…They report an increase of mean crystallite size with depth, possibly indicating a difference in the formation age. However, in our early experiments 15 we have clear evidence that recrystallization occurs as a time-dependent process. Figure 9 shows, for water saturations below 10 %, a slight but clear decrease of the electrical resistivity or the resistivity index with time and decreasing hydrate formation rate.…”

A cylindrical electrical resistivity tomography array for three-dimensional monitoring of hydrate formation and dissociation

“…The results of this modelling correspond very well with the experimental results where hydrates were formed from a methane saturated water phase in glass bead sediments. 8 Schicks et al 9 performed experiments under simulated in situ conditions in a pressure cell. Under a microscope, they also observed hydrate formation in pore spaces without any contact to sediment grains.…”