Methane Hydrates Jake Ross and Yuliana Proenza

1. Methane HydratesJake Ross and Yuliana Proenza The Three Questions What is a Gas Hydrate? What is their potential as an energy resource? What role do they play in global climate change?

2. What is a Gas Hydrate?

3. Hydrate Samples

4. CH4 Hydrate Stability

5. Where are Methane Hydrates located? Found in 4 major location types Subduction zones (e.g., Nankai Trough Japan, Cascadia Basin) Passive Margins (e.g., Blake Ridge on the southeast cost of the US) Off-shore hydrocarbon (e.g., Gulf of Mexico, North Slope Alaska) On-shore Arctic Permafrost (e.g., Mackenzie Delta, Arctic Russia, Arctic Alaska)

6. Where are Methane Hydrates located? Methane hydrate occurs in a zone referred to as the hydrate stability zone. The zone lies roughly parallel to the land or seafloor surface. Permafrost regions, depths about 150 - 2000 m below the surface. In oceanic sediment ocean is at least 300 m deep, depths of 0 - 1,100 m below the seafloor.

7. Where are Methane Hydrates located?

9. What is the potential of CH4 Hydrates as an energy resource

11. Conceptual Drawing of Blake Ridge

12. Why are CH4 Hydrates a good energy resource The gas is held in a crystal structure, therefore gas molecules are more densely packed than in conventional or other unconventional gas traps. Hydrate forms as cement in the pore spaces of sediment and has the capacity to fill sediment pore space and reduce permeability. CH4 - hydrate-cemented strata thereby act as seals for trapped free gas Production of gas from hydrate-sealed traps may be an easy way to extract hydrate gas because the reduction of pressure caused by production can initiate a breakdown of hydrates and a recharging of the trap with gas

13. A Proposed Method For the gas production from hydrates and the seabed stability after the production, we proposed a new concept. The figure illustrates the molecular mining method by means of CO2 injection in order to extract CH4 from gas hydrate reservoirs. The concept is composed of three steps as follows; 1) injection of hot sea water into the hydrate layer to dissociate the hydrates, 2) produce gas from the hydrate, 3) inject CO2 to form carbon dioxide hydrate with residual water to hold the sea bed stable

14. CH4 Hydrates and Climate Change Methane is a very effective greenhouse gas. It is ten times more potent than carbon dioxide. There is increasing evidence that points to the periodic massive release of methane into the atmosphere over geological timescales. Are these enormous releases of methane a cause or an effect of global climate change?

17. The Past A prominent negative shift in d 13C has been recorded in Late Paleocene sediments worldwide. The late Paleocene-early Eocene interval (55.5 mya) was a thermal maximum Ocean bottom waters warmed rapidly by as much 4 degrees C, along with a concurrent rapid shift in d 13C values of all the carbon reservoirs in the global carbon cycle Data from sediments cores suggest that the isotopic shift occurring within no more than a few thousand years Only a catastrophic infusion of d 12C-enriched carbon from methane hydrates could cause such a rapid shift.

18. CH4 Hydrates and the Atmosphere An important aspect of methane hydrates and their affect on climate change is their potential to enter the atmosphere Methane concentration in seawater is observed to decrease by 98% between a depth of 300m and the sea surface as a result of microbial oxidation. The flux of methane into the atmosphere is thus lowered 50-fold (Mienert et al., 1998) However during catastrophic events such as large�scale sediment slumping much higher proportions of methane would be released.

20. The Future of Methane Hydrates Worldwide gas production in the next 30-50 years Areas with unique economic and/or political motivations could see substantial production within 5-10 years We need to better understand the mechanisms of hydrate disassociation and its role in global warming, either as an accelerator or and inhibitor