Intercalation of Gas Hydrates in Clays

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GuggenheimEAR-0207770The working hypothesis of this proposal is that clay/methane-gas hydrate complexes will form under appropriate water-saturated conditions at low temperatures and high gas pressures. In a series of preliminary experiments, we obtained evidence that these complexes indeed can form at these conditions. In these experiments we used an environmental chamber, capable of temperatures from -100 to 200 oC and gas pressures to 75 bars. This chamber, which we developed in-house, allows X-ray scans from 0 to 70 degrees two theta.We propose to examine Na-exchanged and Ca-exchanged montmorillonite and methane under the appropriate conditions to form clay/methane-gas hydrate complexes. In addition, we will examine possible interactions between methane and NH4-exchanged montmorillonite. Our intent is to determine the compositional range of clays that allow gas hydrates to intercalate into clay structures. We will then determine the P-T conditions where these clay/gas-hydrate complexes form, as well as the amounts of gas hydrates that are incorporated in the clay. The discovery of clay/gas-hydrate complexes introduces a new class of materials, which should be of interest in mineralogy, geochemistry, and materials science. As with gas hydrates, these new complexes: (1) may be expected to occur in deep ocean and polar regions (e.g., permafrost, Antarctic ice), (2) may be involved in submarine sediment stability, and (3) may be present on Mars. It is probable that the stability range of clay/gas-hydrate complexes will extend the stability range of gas-hydrate compounds. Also, clay/gas-hydrate complexes may store significant quantities of methane and other hydrocarbons, and thus, these complexes may play an important role in climate changes, much like what has been proposed for gas hydrates.