Poster presented during the 7ªICGH (Edimburgh-UK)

1. An Integrated Study on the Gas Hydrate Area of Umitaka Spur, Joetsu Basin,
Eastern Margin of Japan Sea, using Geophysical, Geological and Geochemical Data
Antonio Fernando Menezes Freire Ryo Matsumoto
Petrobras Research Center (CENPES) The University of Tokyo
fernandofreire@petrobras.com.br ryo@eps.s.u-tokyo.ac.jp
We used 2D single channel seismic (SCS) data to understand the structural-stratigraphic control on the gas hydrates of Umitaka Spur, an anticline located at
the eastern margin of the Japan Sea. On the other hand, sedimentology, stratigraphy and geochemistry of sediments collected by piston- and push-cores,
provide us the tools to understand what is happening at the seafloor in areas with gas hydrates and methane seepages.
Chimney-like structures seem to be strongly controlled by a complex anticlinal axial fault system. In some of them, SCS profiles show high amplitude events
with pull-up structures, probably due to massive and dense accumulation of gas hydrate. A BSR is recognized within gas chimneys and in the eastern flank
of the structure. The anticlinal axial fault system, the convex shape of the spur, and permeable layers as conduits induce gas migration to the top
of the spur, providing strong seepages and giant plumes in the sea water column.
Geochemistry of sediments enabled the characterization of background signatures and the origin of the organic matter of both Holocene and LGM sediments,
on the basis of δ13Corg, TOC/TN ratio. The geochemical signatures of the seep site sediments are similar to those of the deeper LGM sediments. Anomalous
features of seep sites seem to imply migration of sediments as well as water and gas. Gas hydrates cause an increase in the sedimentary volume, inducing the
formation of mounds with older and deeper LGM sediments on the seafloor.
10 11 13 15 16 17 18 19 20 22 23 25 10 11 13 15 16 17 18 19 20 22 23 25
801 37°32' 1.2 - mound
44°N
JAPAN S METI DEEP WELL (Proj.) METI SHALLOW WELL (Proj.) N seep site
pockmark
US-51 - 1.2
Hokkaido 1.0
Sapporo
US-51 03 04 05 06 07 08 09 10 11 13 15 16 17 18 19 20 22 23 25 54 26 27 28 29 108
CHINA
H-I
42°N
1.2
Mound (seep) Depression (pockmark) H-II
1.4 - ? BSR - 1.4
500 km
H-I BSR H-III
40°N
Japan Sea ?
-99‰ δ13C
Akita
1.4 H-II
CH4 H-III Debris Flow Seafloor H-IV
Sakata
Sado Island
Enhanced
TWT (s)
Haizume Fm.
TWT (s)
H-IV
Sendai
38°N
Umitaka Spur Niigata
00 m 1.6 Debris Flow Enhanced Reflectors
Joetsu
-11 1.6 - - 1.6
TWT (s)
Joestu Basin H-V Reflectors H-V
36°N
KOREA Kanazawa
H-VI Gas
e
Honshu Tokyo
a
37°30' 1.8 H-VI Chimney
-11
Hiroshima
00
34°N
Shikoku
e
2.0
Zoom area for fig. 3 1.8 - - 1.8
Pacific Ocean
m
Kyushu Nishiyama Fm. Top of
JK Gas Nishiyama Fm.
i
Nagazaki
32°N
0 100 km
-1000m /U Gas Gas
128°E 130°E 132°E 134°E 136°E 138°E 140°E 142°E
S- 2.2 Chimney Chimney Chimney
10
8 Umitaka Spur Umitaka Spur Umitaka Spur 2.0 - 0 500m 0 500m - 2.0
-1100m
2.4 South Central Northl
-89‰ δ13C 0 1Km
SW NE SW NE
CH4 UMITAKA SPUR
METI_S well NORTH
(2b)
Figure 3: Detailed image of the near-strike SCS section US-51 shown
US-29
37°28' S METI DEEP WELL (Proj.) METI SHALLOW WELL (Proj.) N in figure 2. Reflectors H-I to H-VI can be observed and correlated in
Steep 1.0
US-28
Slope -54‰ δ13C
CH4
Gentle US-51 03 04 05 06 07 08 09 10 11 13 15 16 17 18 19 20 22 23 25 54 26 27 28 29 108 all SCS sections. Note that faults link deep parts of the spur below the
US-27 Mound (seep) Depression (pockmark)
US-26
US-25
Mound (seep)
FIG. 05a
Slope 1.2
top of Nishiyama Formation to the seafloor and to the GHSZ, where
BSR
US-23 H-I
offsets are observed. Pink dashed line is the potential BSR.
. 03
US-22 1.4 H-II
Depression (pockmark) H-III Seafloor
FIG
US-20 Debris Flow
US-19 H-IV Haizume Fm.
US-18 FIG. 04 1.6 Debris Flow Enhanced
-10
TWT (s)
US-17 H-V Reflectors
-47‰ δ13C
00
US-16 CH4 H-VI W Umitaka Spur North METI SHALLOW WELL E
m
US-15 1.8 1.0
US-13 Mound (seep)
Nishiyama Fm. US-29 54 51 53
37°26'
US-11 364 mbsf (~1.3 Ma)
UMITAKA SPUR 2.0 Nishiyama Fm. Zoom area for fig. 3
US-10 1.2
Gas
Depression (pockmark) CENTER 622 mbsf (~1.3 Ma)
Chimney
Water Depth: 971 m
-900
US-09 -67‰ δ13C
US-08 CH4
FIG. 05b 2.2
1.4 BSR Debris Flow
H-I
m
US-07 Umitaka Spur Umitaka Spur Seafloor
-1000m
Umitaka Spur
-900m
H-II
US-06 2.4 South Central Northl Haizume Fm.
0m
3
US-05 0 0 1Km 1.6 G
11 Final Depth: 2088 mbsf (3.3 s TWT) Final Depth: 1027 mbsf ( 2.5 s TWT) H-III
US-5
-
TWT (s)
W
US-04 (2b) Enhanced
UMITAKA SPUR H-IV
US-03 Reflectors Fluid Contact
SOUTH
METI_D well Figure 2: Near-strike SCS profile US-51. Note mounds and pockmarks at the seafloor 1.8
(Flat-Spot) H-V
US-54
51
Debris Flow
Nishiyama Fm.
US-
37°24'
in the central part of the spur, where fracturing is more intense. 2.0 364 mbsf (~1.3 Ma)
H-VI
e
tal slop
t inen 2.2
con km
(a) 53 53
Contour interval = 5m 0 1 2 W E W E
2.4 0 1Km
137°58' 138°00' 138°02' 138°04' US-23 Final Depth: 1027 mbsf (2.5 s TWT)
Figure 1: Location map of Umitaka Spur. Map of the seafloor 1.5 BSR Cahotic H-II
(3a)
Zones
relief showing mounds and pockmarks in a NE-SW trend. Free Gas? 1.0
W Umitaka Spur South METI DEEP WELL E
1.6 Debris Flo 51 54 53 tal
Stars indicate plume/seep sites. Open circles indicate carbon ws US-03 Water Depth: n
TWT (s)
Enhanced Water H-III ine
885 m nt
isotope analyses of mud-gas, suggesting thermogenic origin 1.7
Reflectors Fluid
Contact
Debris Flo
ws
1.2
H-I
co pe
slo
at the central part of the spur. The 2D single channel seismic (Flat-Spot)
1.4 Seafloor H-II
H-III
survey is shown. 0 500m 0 H-IV 500m
1.6
Haizume Fm. H-IV
54 54
1.8
TWT (s) H-V Debris-Flow
W E W E
(b) 53 53 ? H-VI
US-19 1.8 ?
W E W E
mounds seep site
H-II US-08
1.5 Cahotic Zones Debris Flo
1.2 - ws 2.0 Nishiyama Fm.
? 622 mbsf (~1.3 Ma)
1.3 - H-III
TWT (s)
offset Debris Flo
ws 2.2
1.4 - 1.6
“pull-up” BSR BSR
TWT (s)
? Enhanced
1.5 - 2.4 0 1Km
Enhanced H-IV Reflectors Cahotic Final Depth: 2088 mbsf (3.3 s TWT)
1.6 - gas Reflectors 1.7 Zone (3b)
Debris Flo
0 500m 0 500m ws
chimney H-V Fluid
Contact
Figure 6: Dip SCS profiles US-29 and US-03, respectively at the
Figure 4: Detailed image of dip section US-19 showing pull-up 1.8
0 500m 0 (Flat-Spot) 500m
northern and the southern part of Umitaka Spur. METI Deep
structure within gas chimneys inside the GHSZ. Note that the Figure 5: Detailed image of dip SCS profiles US-23 and US-08. Chaotic zones are zones and Shallow wells are plotted. See figure 1 for location of profiles
seismic events, BSR and enhanced reflectors are offset by gas where reflectors are not continuous, and are here interpreted as debris-flow deposits. Note and wells.
chimney boundary faults. a flat reflector (light blue dashed line) associated to the debris representing a possible
gas/water contact just below the BGHSZ on the western flank of Umitaka Spur. 1.0
US-19
E
In this case, gas hydrates above represent a seal for a shallow free-gas accumulation below. 1.2
W
US-013
51 54 53
1.4
1.2 -
137°58' 138°00' 138°02' 138°04'
37°32' 801 37°32' 1.6
1.4 -
Transfer Zone Mound Seep Sites
JOETSU KNOLL
Seafloor Lineaments 1.8 Gas
TWT (s)
1.6 -
SOUTH Assimetrical Anticline Axis Chimney
BSR Area (projected)
Normal or Vertical Faults (seafloor) 2.0
1.8 - Debris-Flow
TWT (s)
1 Gas Chimney (seafloor) Occurrence Area (projected)
2.2
2.0 -
Free-Gas Occurrence
Gas Hydrate Target (projected on the seafloor)
Area (projected)
2.4
2.2 -
GH
-11
37°30' 37°30'
OU
00
2.4 -
W Structural and Stratigraphic Gas Focused Model E
m
TR
Giant Plumes
potential Mud Gas Analysis
KA
0 1Km Concentration of Methane Seeps
13
and Gas Hydrate Seafloor Outcrops δ CCH4 > -60‰ Seafloor
TA
Mud Gas Analysis
free-gas Mound Depression (pockmark)
MI