Gas hydrate formation in Gulf of Mexico sediments
Dearman, Jennifer L.
AdvisorRogers, E. Rudy
Hill, J. Priscilla
French, Todd W.
Gas hydrate formation was studied in Gulf of Mexico (GOM) sediments. Sediments studied were from six-meter long cores from Mississippi Canyon Block 118 and a 27-meter core from a cruise in 2002 of the Marion Dufresne. These sediments retained their in situ seawater before testing. Hydrate formation rate and induction times were measured. The hydrate memory effect was studied in GOM sediments with and without in situ seawater. Hydrate induction time was short when in situ seawater was present. Bioproducts adsorbed on particles in the sediments are postulated to shorten the induction times by maintaining seawater structuring around coated particles. Hydrate nucleation was studied by Dynamic Light Scattering and Scanning Electron Microscopy. Particles around 50 to 100 nm nucleated hydrate formation. These small nucleating particles appeared to be clays or surfactant molecules and interactions thereof. Hydrate capillaries were studied and found to be at least 100 nm in diameter because the sediment nucleating particles with bioproducts diffused through the hydrate capillaries. Large complexes of nontronite smectite clay and Emulsan, an anionic biosurfactant, were found to facilitate hydrate formation. It was determined that Emulsan entered the interlayer of nontronite. The clay contents of the GOM sediments were determined. All sediments contained smectite, illite, chlorite, and kaolinite in different proportions. The study gave new insight into the gas hydrate formation mechanism in seafloor sediments.