gas hydrates challenge
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Gas hydrates challenge2012-01-18
Where do we find hydrates?
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CHALLENGE:
Temperature control
How can we produce from hydrate reservoirs without flow-assurance issues?
Q:
There are two factors that will cool a system during gas production from hydrates: The Joule-Thomson effect (expanding gas cools down); and hydrate dissociation (melting) is an endothermic reaction (absorbes heat). Since the reservoir will, by definition, be within hydrate stable thermodynamic conditions, a slight decrease in temperature may hydrate (either near, or in the wellbore).
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Q:
CHALLENGE:
Sand control
There is only one production test currently that has shown proof of concept in regards to gas production from gas hydrates. This test was done in Northern Canada – at the Mallik site. The hydrate reservoir is shallow below permafrost, so the sediments where unconsolidated. This showed that sand control is of great importance. This is also expected to be the case for some marine reservoirs.
How can we produce gas from hydrate reservoirs in unconsolidated sediments more efficiently?
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Q:
CHALLENGE:
Water control
How do we dispose of the water in hydrate production?
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Hydrate production will most likely result in large amounts of water. This poses several issues not typically handled: The water has to be disposed some way (and reinjection is not an option initially due to the increase in reservoir pressure); there will be a “water lift” issue (due to large amounts of water and low pressure gas).
Where do we find hydrates?
BGHZ
GH
SZ
Dep
th
Temperature
Temperature
hydrate stability
GH
OZ
BGHZ
GH
SZ
Dep
th
Temperature
Temperature
hydrate stability
Base Permafrost
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Classification: Internal 2011-06-
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Gas hydrates occur in a wide variety of geologic settings and modes of occurrence
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Modified from Boswell 2009
Marine sands
Fractured muds
Mounds
Undeformed mudsUndeformed muds
Arctic sands85-10,000 tcf gas(≤ 2.8·105 GSm3)(≤ 1.7·1012 boe)
~100,000 tcf gas(~2,8·106 GSm3)(~1,7·1013 boe)
Hydrate in sands• Gas hydrate resources housed in sand
reservoirs• Shallow “conventional” reservoirs
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Solid hydrate• Vein-filling, nodules and massive seafloor
mounds• Low resource density/environmentally
sensitive
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The “Background”• Disseminated gas hydrate in fine-grained
marine sediments• Large volumes • Very low (1-3 %) resource density
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◄◄ Coarse-grained continental sand ◄ Pore-filling marine turbidite sand
Vein-filling in clay Nodules in clay Massive sea floor mounds
Disseminated in mud
Korea India GoM
China
Canada Japan
Gas-hydrate-bearing sands seem the most feasible initial targets for energy recovery
Gas-hydrate-bearing sands seem the most feasible initial targets for energy recovery
