constraining the thermal history of carbonate reservoirs kristin... · 2017. 6. 5. · nafun abu...
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Constraining the thermal history of carbonate reservoirsKristin BergmannVictor P. Starr Assistant Professor Department of Earth, Atmospheric and Planetary Sciences
MIT Earth Resources Laboratory 2017 Annual Founding Members Meeting May 31, 2017
Carbonate reservoirs reflect shallow crustal processes that occlude or enhance porosity
METAMORPHICREALM
METEORIC REALM
SUBSURFACE REALM
DOLOMITIZATION
DOLOMITIZATION
DISSOLUTION
DISSOLUTION
DISSOLUTION
CEMENTATION
CEMENTATION
CEMENTATION
DISSOLUTIO
N
DOLOMITIZATIO
N MARINE REALM
CCD
ACD
BRINE
SEAWATER
RAINW
ATER
(Modified from Moore, 1989)DOLOMITIZATION
Modified from Moore, 1989
Fe
250 μm 250 μm
250 μm 60 μm
Plane Polarized Light
SEM Backscatter Image
Plane Polarized Light
Plane Polarized Light
Plane Polarized Light
Electron Microprobe Elemental Map
110
25
{001}
50 μm
Tracking when and where key events occur is a function of T and W
METAMORPHICREALM
METEORIC REALM
SUBSURFACE REALM
DOLOMITIZATION
DOLOMITIZATION
DISSOLUTION
DISSOLUTION
DISSOLUTION
CEMENTATION
CEMENTATION
CEMENTATION
DISSOLUTIO
N
DOLOMITIZATIO
N MARINE REALM
CCD
ACD
BRINE
SEAWATER
RAINW
ATER
(Modified from Moore, 1989)DOLOMITIZATION
Modified from Moore, 1989
Traditional δ18O measurements depend on both T and W
Tem
pera
ture
(˚C)
100
200
0
0 +10 -10
δ18Ocalcite(VSMOW) = 30 ‰
δ18Owater (‰; VSMOW)
CaC16O3 + H218O CaC18O16O2 + H216O<-----> Keq
Clumped isotope thermometry primer
Ca13C16O3 + Ca12C18O16O Ca13C18O16O2 + Ca12C16O3<-----> Keq
1.0005
1.0004
1.0003
1.0002
1.0001
0 2 4 6 8 10 12 14
300 100 25 0
Keq
106/T2 (K)
Calcite
More Clumped Bonds
Random Bonds
T (°C)
DFT Model of clumping in calcite from Schauble et al., 2006
Tem
pera
ture
(˚C)
water Lakes and Evaporating
marine
Late diagenesis
Early diagenesis
Meteoric hydrothermal
Metamorphic
100
200
0
0 +10 -10
Sea soils
δ18Ocalcite (VSMOW) = 30 ‰
δ18Owater (‰; VSMOW)
CaC16O3 + H218O CaC18O16O2 + H216O<-----> Keq
Solid state reordering
• Apatite and aragonite will begin to reorder >100°C over 106 years (Stolper and Eiler, 2015 and Piasecki et al., 2015)
• Calcite will begin to reorder at >150°C over 106 - 108 years and fully-equilibrates above 200°C (Henkes et al., 2014; Stolper and Eiler, 2015)
• Dolomite does not reorder over ~ 250°C over 108 years (Lloyd and Eiler, 2014)
Stolper and Eiler, 2015
The Bergmann Lab approach
Mn
100 200 300 400
100
200
300
400 0
20
40
60
80
100
Precipitating temperature and fluid compositions
Trace metal and isotopic heterogenetity
Sedimentological context andpetrographic preservation
SIMS, Electron Microprobe, XRD, XANES, ICP-AES
Clumped Isotope Thermometry
Field observations and EBSD mapping
Jurassic
Silurian
Ordovician
Cambrian
Period
Triassic
Carbonif.
Permian
Ediacaran
Cryogenian
Quaternary–
Palaeogene
Cretaceous
Devonian EDIA
CARA
NCA
MBR
IAN
ARA541 Ma
Perio
dG
roup
NAF
UN
ABU
MAH
ARA~635 Ma
CRYO
GEN
IAN
I II
III
66 Ma
252 Ma
541 Ma
Diagenetic trends in marine carbonatesSultanate of Oman
Modified from Forbes et al., 2010
Group 1: Eocene to Permian■ Thick limestones to mixed limestones and siliclastics
■ Minor dolomite in the Permian■ Range of petrographic fabrics from micrite to grainstone
with varying degrees of fossil preservation and cementation
Group II: PC-C Ara Group■ Carbonate ‘stringers’ floating in evaporites■ Dominantly dolomite although some calcite
■ Range of petrographic fabrics with fine to coarse grained interlocking recrystallized fabrics
Group III: Ediacaran Nafun Group
■ Thick dolomites to mixed limestones and siliclastics■ Range of petrographic fabrics from micrite to
grainstone to boundstone with similar preservationcharacter to Group I
Diagenetic trends in marine carbonates:Cross section of central Oman
0 100 kmN
Arabian Sea
500 km
SAUDIARABIA
IRAN
A
A’
CentralOman High
0
3
6
9
12Ghaba SaltBasin
CentralOman High
South OmanSalt Basin
Depth (km
)
Paleozoic siliciclasticsAra SaltAra Carbonate StringersNafun GroupAbu Mahara
Basement
Map Legend
Precambrian OutcropSalt Basin
Well locationsSalt Dome locationOutcrop locations
South OmanSalt Basin
Ghaba SaltBasin
Al Huqf
A A’
Permian - present carbonates
Modified from Al Siyabi, 2005
20 μm500 μm
Eocene [357m, BT = 43°C]: T = 30 ± 2°C δ18Owater = 0.2 ± 0.5‰ (n=3)
Plane Polarized Light SEM Backscatter Image
Jurassic [1038 m, BT = 54°C]: T = 34 ± 2°C δ18Owater = 0.3 ± 0.3‰ (n=2)
40 μm500 μm
Plane Polarized Light SEM Backscatter Image
Cretaceous [500.8 m, BT = 49°C]: T = 32 ± 4°C δ18Owater = 0.2 ± 0.8‰ (n=2)
2 cm
spar T = 48 ± 4°C; δ18Owater = 2.3 ± 0.7‰ (n=2)
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
●
●
●
●
●
●
●
●●●
●●
●
●●
●
●
25 50
Perm
ian
Jur.
Cret
aceo
usTe
rtia
ry
Dep
th (k
m)
Temperature (ºC)
Group I: Eocene to Permian carbonatesA subsurface well
Eocene-Permian calcite
Permian dolomite
●Void and fracture calcite
limestone
dolomite
evaporitesandstone
siltstone geothermal gradient
Bulk carbonatesshow ‘stabilization’ at low temperatures and very shallow depths(30-35°C)
0
5
●
●
●●
●●● ●●
●●
●●●●
●● ●
●
●●
●●●●●●●
●●●●●●
-5 0
-5
0
●
●
●●●
●●●● ●●●●
●●●●
25 50Temperature (°C)
δ18O
min
eral (‰
; PD
B)δ18
Ow
ater
(‰; V
SMO
W)
δ18Omineral (‰; PDB)
Eocene-Permian calcite
Permian dolomite
●Void and fracture calcite
Group I: Eocene to Permian carbonates v. shallow stabilization - mod. W/R
Low W
/R
High W/R
0
5
●
●
●●
●●● ●●
●●
●●●●
●● ●
●
●●
●●●●●●●
●●●●●●
-5 0
-5
0
●
●
●●●
●●●● ●●●●
●●●●
25 50Temperature (°C)
δ18O
min
eral (‰
; PD
B)δ18
Ow
ater
(‰; V
SMO
W)
δ18Omineral (‰; PDB)
Eocene-Permian calcite
Permian dolomite
●Void and fracture calcite
Group I: Eocene to Permian carbonates v. shallow stabilization - mod. W/R
Low W
/R
High W/R
100 μm500 μm
PC-C (Ara Group) [3148 m, BT = 77°C] T = 75 ± 5°C δ18Owater = 7 ± 1‰ (n=2)
Plane Polarized Light SEM Backscatter Image
Group II: Precambrian-Cambrian Ara GroupA subsurface well
3.0
2.5
2.0
1.5
1.0
0.5
0.0
●
●
●
●●
●
●●●
●
●●
●●●●●
●●●
●●
● ●●
25 50 753.5
Cam
bria
nO
rdov
icia
nPe
rmia
nJu
r.Cr
etac
eous
Tert
iary
Carb
.
Dep
th (k
m)
Temperature (ºC)
Non-SOSB Birba dolomite
Eocene-Permian calcite
Permian dolomite
●Void and fracture calcite●
Nafun Group calcite
Nafun Group dolomite
●● SOSB calcitelimestone
dolomite
evaporitesandstone
siltstone geothermal gradient
●
●●●● ●●●●●●
●●●●●● ●●●●● ●●●
25 50 75 100 125Temperature (°C)
5
4
3
2
1
0D
epth
(km
)
Eocene - PermianPrecambrian-Cambrain Ara GroupPrecambrian Birba carbonates
Group II: Precambrian-Cambrian Ara Groupsample Ts approach the current geotherm
0 100 kmN
Arabian Sea
500 km
SAUDIARABIA
IRAN
A
A’
CentralOman High
0
3
6
9
12Ghaba SaltBasin
CentralOman High
South OmanSalt Basin
Depth (km
)
Paleozoic siliciclasticsAra SaltAra Carbonate StringersNafun GroupAbu Mahara
Basement
Map Legend
Precambrian OutcropSalt Basin
Well locationsSalt Dome locationOutcrop locations
South OmanSalt Basin
Ghaba SaltBasin
Al Huqf
A A’
Permian - present carbonates
0 100 kmN
Arabian Sea
500 km
SAUDIARABIA
IRAN
A
A’
CentralOman High
0
3
6
9
12Ghaba SaltBasin
CentralOman High
South OmanSalt Basin
Depth (km
)
Paleozoic siliciclasticsAra SaltAra Carbonate StringersNafun GroupAbu Mahara
Basement
Map Legend
Precambrian OutcropSalt Basin
Well locationsSalt Dome locationOutcrop locations
South OmanSalt Basin
Ghaba SaltBasin
Al Huqf
A A’
Permian - present carbonates
0 100 kmN
Arabian Sea
500 km
SAUDIARABIA
IRAN
A
A’
CentralOman High
0
3
6
9
12Ghaba SaltBasin
CentralOman High
South OmanSalt Basin
Depth (km
)
Paleozoic siliciclasticsAra SaltAra Carbonate StringersNafun GroupAbu Mahara
Basement
Map Legend
Precambrian OutcropSalt Basin
Well locationsSalt Dome locationOutcrop locations
South OmanSalt Basin
Ghaba SaltBasin
Al Huqf
A A’
Permian - present carbonates
Group II: Precambrian-Cambrian Ara Groupδ18Owater compositions are enriched
●
● ●●●●● ●●●●
●●●●●● ●●●●●●● ●
−5 0 5 10 15δ18Owater (VSMOW, ‰)
5
4
3
2
1
0D
epth
(km
)
Eocene - PermianPrecambrian-Cambrain Ara GroupPrecambrian Birba carbonates
0 100 kmN
Arabian Sea
500 km
SAUDIARABIA
IRAN
A
A’
CentralOman High
0
3
6
9
12Ghaba SaltBasin
CentralOman High
South OmanSalt Basin
Depth (km
)
Paleozoic siliciclasticsAra SaltAra Carbonate StringersNafun GroupAbu Mahara
Basement
Map Legend
Precambrian OutcropSalt Basin
Well locationsSalt Dome locationOutcrop locations
South OmanSalt Basin
Ghaba SaltBasin
Al Huqf
A A’
Permian - present carbonates
0 100 kmN
Arabian Sea
500 km
SAUDIARABIA
IRAN
A
A’
CentralOman High
0
3
6
9
12Ghaba SaltBasin
CentralOman High
South OmanSalt Basin
Depth (km
)
Paleozoic siliciclasticsAra SaltAra Carbonate StringersNafun GroupAbu Mahara
Basement
Map Legend
Precambrian OutcropSalt Basin
Well locationsSalt Dome locationOutcrop locations
South OmanSalt Basin
Ghaba SaltBasin
Al Huqf
A A’
Permian - present carbonates
0 100 kmN
Arabian Sea
500 km
SAUDIARABIA
IRAN
A
A’
CentralOman High
0
3
6
9
12Ghaba SaltBasin
CentralOman High
South OmanSalt Basin
Depth (km
)
Paleozoic siliciclasticsAra SaltAra Carbonate StringersNafun GroupAbu Mahara
Basement
Map Legend
Precambrian OutcropSalt Basin
Well locationsSalt Dome locationOutcrop locations
South OmanSalt Basin
Ghaba SaltBasin
Al Huqf
A A’
Permian - present carbonates
●
●
●
●
●
●
●
●
●
●
●
●
●
●
0
●●
●
●
●●
●
25 75 125Temperature (°C)
-5
δ18O
min
eral (‰
; PD
B)
0
5
10
15
δ18O
wat
er (‰
; VSM
OW
)
-5δ18Omineral (‰; PDB)
Burial Fluids Burial Fluids
0
5
10 ●●●
●
●
●
●●● ●●●
●
●
●
●●●
-10 -5 0
-10
-5
0●●●●
●
●
●●
●
25 50 75 100Temperature (°C)
δ18O
min
eral (‰
; PD
B)δ18
Ow
ater
(‰; V
SMO
W)
δ18Omineral (‰; PDB)
● Qarn Alam Salt Dome
● SOSB calcite
non-SOSB Birba dolomite
SOSB dolomite
Group II: Precambrian-Cambrian Ara Group low W/R ratio Lo
w W/R
High W/R
Ediacaran (Nafun Group) [surface, est. 1-2km max] T = 55 ± 1°C, δ18Owater = -1.6 ± 0.4‰ (n=3)
80 μm500 μm
Plane Polarized Light SEM Backscatter Image
4.0
3.8
3.6
3.4
3.2
3.0
● ●
●
50 75 1004.5
Naf
unAr
a
Edia
cara
n
Dep
th (k
m)
Temperature (ºC)
Group III: Ediacaran Nafun Group A subsurface well
Non-SOSB Birba dolomite
Nafun Group calcite
Nafun Group dolomite
●limestone
dolomite
evaporitesandstone
siltstone geothermal gradient
limestone
dolomite
boundstone including stromatolites and laminites
grainstone including oolitic
mudstone
wackestone and packstone
teepees sandstone
siltstone
Non-SOSB Birba dolomite
Nafun Group calcite
Nafun Group dolomite
●
2800
2600
2400
2200
2000
200
400
600
800
1000
4200
4000
3800
3600
3400
3200
3000
200
400
600
800
1000
1200
Well “T”
25 50 7525 50 75 25 50 75
25 50 75
Temperature (˚C)
Khufai Dome Well “MQ”Mukhaibah Dome
T range is spatially and stratigraphically consistentfor both dolomite and calcite in Nafun Group
(sedimentology from Bergmann, 2013 and Osburn, 2013)
0 100 kmN
Arabian Sea
500 km
SAUDIARABIA
IRAN
A
A’
CentralOman High
0
3
6
9
12Ghaba SaltBasin
CentralOman High
South OmanSalt Basin
Depth (km
)
Paleozoic siliciclasticsAra SaltAra Carbonate StringersNafun GroupAbu Mahara
Basement
Map Legend
Precambrian OutcropSalt Basin
Well locationsSalt Dome locationOutcrop locations
South OmanSalt Basin
Ghaba SaltBasin
Al Huqf
A A’
Permian - present carbonatesAl Huqf Outcrop
Well A
Well B
-5
0
5
-10 -5 0
-10
-5
0
25 50 75
0
5
●●
●●
●
●
●●●●
●
●
●
●
●●
●●●
●
●●
● ●●●
●●
●
●
●
●
●●
●● ●●
●●
●
●
●●●●
●
●
●
●
●●
●●●
●
●●
●●● ●
●●
●
●
●
●
●●
●●
-10 -5
-10
-5
●● ●
●●●
●●●●
● ●●
●
●●
●
●●● ●●
●
●
●
●●
●
●
● ●
●
● ●●●
25 50 75Temperature (°C)
δ18O
min
eral (‰
; PD
B)δ18
Ow
ater
(‰; V
SMO
W)
δ18Omineral (‰; PDB)
Temperature (°C)δ18
Om
iner
al (‰
; PD
B)δ18
Ow
ater
(‰; V
SMO
W)
δ18Omineral (‰; PDB)
Nafun Group calciteNafun Group dolomite
●
Low W
/R
High W/R
Group III: Ediacaran Nafun Group change in fluid comp., low W/R in calcite
●
●●●● ●●●●●●
●●●●●● ●●●●● ●●●
25 50 75 100 125Temperature (°C)
5
4
3
2
1
0
Dep
th (k
m)
Eocene - PermianPrecambrian-Cambrain Ara Group
Precambrian Nafun GroupPrecambrian Birba carbonates
Group III: Ediacaran Nafun Group Ts in between Groups I & II
0
3
6
9
12D
epth
(km
)Ghaba Salt
BasinCentral
Oman HighSouth Oman
Salt Basin
A A’
●
● ●●●●● ●●●●
●●●●●● ●●●●●●●●
−5 0 5 10 15δ18Owater (VSMOW, ‰)
5
4
3
2
1
0
Dep
th (k
m)
Eocene - PermianPrecambrian-Cambrain Ara Group
Precambrian Nafun GroupPrecambrian Birba carbonates
Group III: Ediacaran Nafun Group δ18Owater marine-like
Observations:■ Nafun Group carbonates are petrographically well-preserved
■ Co-occuring calcite and dolomite indicate similar T
■ δ18Owater compositions areseawater like for both calcite and dolomite
Options: ■ partial solid state diffusion and long term change in δ18Owater
■ change in temperature of shallowburial ‘stabilization’ or initial temperature
Summary
■ Using a combination of petrographic, microanalytical and clumped isotope analyses of specific textures we can reconstruct the timing of events critical to the evolution of carbonate reservoirs and the thermal history of basins
■ Results from Oman indicate dolomites and limestones are more susceptible to burial diagenetic processes than solid state diffusion between 0-6 km over geologic timescales.
■ Group I of Eocene-Permian limestones and dolomites suggest very early ‘stabilization’. Group II Ara Group limestones and dolomites show variable closed system behavior. Group III Nafun Group data are consistent with a higher temperature of ‘stabilization’ at very shallow depths which could indicate the Ediacaran was 5-20°C warmer than the recent Phanerozoic.