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A GLOBAL OUTLOOK ON METHANE GAS HYDRATES
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Table 3.1-b:
Production setting and associated environmental considerations for marine gas hydrate deposits
1. Likely commerciality time-line (i.e., produceable/non-produceable in the near future)
2. Water Depth
3. NGS/BS: Norwegian Greenland Sea and Barents Sea
Reservoir type
Marine –
“shallow”
Sand- host
sediment
Marine
– “deep”
Sand-host
sediment
Marine –
Mud host
sediment
Marine –
Solid hydrate
Environmental response
– Shallow reservoir
depths and weak
sediment strengths
above producing interval
pose unique challenges
to field development
– Conventional
experience worldwide
is limited in similar
settings, however
engineering design
methods are well
developed
– Conventional
experience worldwide
is limited in similar
settings, however
engineering design
methods are well
developed
– Not Considered
– Non traditional
extraction methods
may be destructive to
sea floor biological
communities and cause
sea floor settlement
Drilling, completion & production
– Conventional drilling practice & sand
control/flow assurance measures
– Horizontal drilling may be difficult
due to shallow reservoir and weak
formation-strength
–Unconventionalsurfaceconductorand
casing design due to weak formations
– Dissociation primarily through
pressure draw-down (down-hole pump)
– Operational challenges owing to cold
reservoir temperatures and formation
mobilitywhengashydrate isdissociated
– A water-disposal strategy is likely to
be required
–Sealintegritymaybeanissueduetolack
of sediment strength and consolidation
– Conventional drilling practice & sand
control/flow assurance measures
– Horizontal drilling may be difficult
due to shallow reservoir and weak
formation-strength
– Dissociation primarily through
pressure draw-down (down-hole pump)
– A water-disposal strategy is likely to
be required
– A number of scientific and
exploratory research wells have
successfully penetrated these
deposits using conventional drilling
methods
– It is unlikely that these deposits
will be developed using conventional
industry completion/production
methods
– Not Considered
Site survey & foundation considerations
– Conventional approach to hazard
delineation and engineering design
– Shallow settings may present
increased risk of sea floor instability
and disruption of shallow ecosystems
– Unique challenges may be
encountered related to geologic
settings such as active tectonic
continental margins where there
is increased seismic activity and
pervasive sediment deformation
– Conventional approach to hazard
delineation and engineering design,
ease of application of existing
approaches increases with increasing
reservoir depth
– Conventional experience worldwide
is limited in similar settings, however
engineering design methods are well
established
– Not considered for fracture fill
– Not Considered
Production maturity
1
– Discovered technically
recoverable resources (Gulf of
Mexico & Japan)
– First offshore production test
in 2013 (Nankai Trough)
– First production may occur in
Asia from c. 2020
As above
–Conventionalpractice in industry
wouldbetoavoidtheseoccurrences
due to low resource density
–Modeling to date shows no clear
viable production mechanism
– Conventional practice in
industry would be to avoid these
occurrences despite moderate to
high gas hydrate saturations, due
to geo-mechanical instability and
restriction of fluid flow
– Conventional practice in
industry would be to avoid
these occurrences due to their
unusual geotechnical
properties and association with
unique biological communities
Reservoir setting
Shallow
– < 250 m below sea floor
– > 500 m WD2
– Pore-space occurrence
Deep
– > 250 m below sea floor
– > 1000 m WD
– Pore-space occurrence
– Sites: AC 818, WR 313, GC
955 (GoM), Beta (Nankai
Trough), UBGH2-2_2,
UBGH2-6 (Ulleung Basin)
Disseminated
– Widespread occurrences
– High volume but low
resource density
– Sites: Blake Ridge (USA)
Fracture-fill
– Widespread occurrences
– High volume but low
resource density
– Sites: KG Basin (India):
Ulleung Basin (Korea); Gulf
of Mexico (USA)
Sea floor:
– Massive (mounds)
– Sites: GoM, Baltic Sea,
Black Sea, Bering Sea, Barkley
Canyon (Canada) NGS/BS3
Vents:
– Massive, disseminated &
fracture-filling (?)
– Sites: Bering Sea, NGS