Arctic methane hydrate
deposits above and
below the lower limit of
Drilling
Drill
permafrost
rig
ship
Bottom of
Biogenic methane
permafrost
Hydrate
generated by
mounds
bacterial action in
on seafloor
shallow sediments
Faults provide
Methane
conduits for
hydrate deposits
methane seeps
below seafloor
Slow seepage of thermogenic methane from below
333
Methane from Gas Hydrates
FiGUre 12.4 Types of methane hydrate deposits. (Adapted from “Methane hydrate—The
world largest natural gas resource is trapped beneath permafrost and ocean sediments,”
Geology.com, a communication, 2013.)
are believed to be formed by the migration of gas from depth along geological
faults, followed by precipitation, or crystallization on contact of the rising gas
stream with cold seawater. Methane hydrates are also present in deep arctic
sea cores and record a history of atmospheric methane concentrations dating to
800,000 years ago [17–27].
In polar regions, methane hydrates are found where temperatures are cold enough
for onshore and offshore permafrost to be present. In offshore sediments, methane
hydrates are found at water depths of 300–500 m, according to prevailing water temperatures. Continental deposits have been located in Siberia and Alaska in sandstone
and siltstone beds at depth <800 m. Oceanic deposits seem to be widespread in
the continental shelf and can occur within the sediments at depth or close to the
sediment–water interface. They may cap even larger deposits of gaseous methane. In
2008, Canadian and Japanese researchers extracted a constant stream of natural gas
from Mallik gas hydrate field in the Mackenzie River delta [17,36,39,43,48,49,51]
(USGS, 2012, pers. comm.). This hydrate field was first discovered by Imperial Oil
Co. in 1971–1972.
The occurrence of gas hydrates on the Alaska North Slope was confirmed
in 1972 in the northwest part of the PBU (Prudhoe Bay Unit) field [17,46,48,49]
(USGS, 2012, pers. comm.), and the North Slope now is known to contain several well-characterized gas hydrate deposits. The methane hydrate stability zone
deposits above and
below the lower limit of
Drilling
Drill
permafrost
rig
ship
Bottom of
Biogenic methane
permafrost
Hydrate
generated by
mounds
bacterial action in
on seafloor
shallow sediments
Faults provide
Methane
conduits for
hydrate deposits
methane seeps
below seafloor
Slow seepage of thermogenic methane from below
333
Methane from Gas Hydrates
FiGUre 12.4 Types of methane hydrate deposits. (Adapted from “Methane hydrate—The
world largest natural gas resource is trapped beneath permafrost and ocean sediments,”
Geology.com, a communication, 2013.)
are believed to be formed by the migration of gas from depth along geological
faults, followed by precipitation, or crystallization on contact of the rising gas
stream with cold seawater. Methane hydrates are also present in deep arctic
sea cores and record a history of atmospheric methane concentrations dating to
800,000 years ago [17–27].
In polar regions, methane hydrates are found where temperatures are cold enough
for onshore and offshore permafrost to be present. In offshore sediments, methane
hydrates are found at water depths of 300–500 m, according to prevailing water temperatures. Continental deposits have been located in Siberia and Alaska in sandstone
and siltstone beds at depth <800 m. Oceanic deposits seem to be widespread in
the continental shelf and can occur within the sediments at depth or close to the
sediment–water interface. They may cap even larger deposits of gaseous methane. In
2008, Canadian and Japanese researchers extracted a constant stream of natural gas
from Mallik gas hydrate field in the Mackenzie River delta [17,36,39,43,48,49,51]
(USGS, 2012, pers. comm.). This hydrate field was first discovered by Imperial Oil
Co. in 1971–1972.
The occurrence of gas hydrates on the Alaska North Slope was confirmed
in 1972 in the northwest part of the PBU (Prudhoe Bay Unit) field [17,46,48,49]
(USGS, 2012, pers. comm.), and the North Slope now is known to contain several well-characterized gas hydrate deposits. The methane hydrate stability zone