HR: 1340h
AN: OS23A-1064    [Abstracts]
TI: Trace Element Analysis as an Exploration Tool for Unconfined Class 2 Hydrate Deposits
AU: Johnson, A D
EM: artjohnson@hotmail.com
AF: Hydrate Energy International, 612 Petit Berdot Drive, Kenner, LA 70065, United States
AU: * Max, M P
EM: mmax@mdswater.com
AF: MDS Research, 1601 3rd St. South, St. Petersburg, FL 33701, United States
AU: Osegovic, J P
EM: josegovic@mdswater.com
AF: MDS Research, 1601 3rd St. South, St. Petersburg, FL 33701, United States
AU: Brazel, L
EM: leslie@mdswater.com
AF: MDS Research, 1601 3rd St. South, St. Petersburg, FL 33701, United States
AU: Tatro, S
EM: statro@mdswater.com
AF: MDS Research, 1601 3rd St. South, St. Petersburg, FL 33701, United States
AB: Hydrate system analysis, analogous to hydrocarbon system analysis, is based on confirming significant gas flux, suitable thickness of hydrate stability zone, and suitably porous and permeable hydrate ‘trap' beds in which economically significant hydrate crystallization may take place. Unconfined Class 2 hydrate deposits, which form by crystallization of dissolved natural gas in more porous and permeable sediments whose pore fluids may vent from the seafloor carry the dissolved rejected material. Analysis of superficial pore or vent water may provide a sensitive means of suggesting whether the water was once associated with hydrate crystallization. The rejection of dissolved ions and compounds during carbon dioxide hydrate precipitation on a chilled surface was determined to quantify the reject rate of specific materials from the hydrate matrix. Seawater and seawater doped with boric acid (H3BO3, MW 61.83 g/mol) and sodium borate decahydrate (Na2B4O7*10H2O, MW 381.37 g/mol) were used as crystallization solvents. Initial boron concentrations ranged from 4.1 to 27mg/L. Hydrate formation occurred with significant rejection of boron from the hydrate matrix, increasing the concentration in the crystallizing fluid. The initial boron concentration level did not affect the rejection efficiency, determined by comparing the initial concentration of boron to the concentration in the hydrate melt water. In addition to boron, naturally occurring calcium and magnesium concentration levels were also studied and showed a similar concentration reduction. Our experiments have shown that non-ionic dissolved species that occur in sediment pore water, in which hydrate may form, are rejected and concentrated during hydrate formation. The measurement of NaCl may provide a clue to the water having once been involved in subjacent hydrate formation, but other species that do not have additional crystallization opportunities in the sediment may be better clues to the extent of a hydrate formation. Identification of characteristic indicators of hydrate system participation would allow rapid sampling and analysis of seafloor water samples to be used as an exploration tool.
DE: 0933 Remote sensing
DE: 1030 Geochemical cycles (0330)
DE: 1050 Marine geochemistry (4835, 4845, 4850)
DE: 3004 Gas and hydrate systems
SC: Ocean Sciences [OS]
MN: 2007 Fall Meeting