Recovery of Methane from Hydrate Formed in a Variable Volume Bed of Silica Sand Particles

The decomposition of methane hydrate crystals formed in sediment at 1.0, 4.0, and 7.0 degrees C was studied in a new apparatus designed to accommodate three different size volume beds of silica sand particles. The sand particles are microporous with a 0.9 nm pore diameter and have an average diameter equal to 329 mu m. The hydrate was formed in the interstitial spaces between sand particles, and the hydrate crystal decomposition was driven by heating (thermal stimulation). The amount of methane released from the dissociating hydrate in each experiment (methane recovery curve) was determined, and it was shown that the release of gas proceeds in two stages in terms of rate. The rate of methane release (recovery) per mole of water depends on the bed size for the First stage of hydrate dissociation. The second stage rate does not depend on the bed size. This work suggests that the comparison of simulated data to experimental results from laboratory synthesized hydrate and possibly from natural samples should be done with more than one sample-size data.