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Helium isotopic distribution of Australian natural gases
Chris Boreham1, Dianne Edwards1 and Robert Poreda2
19th Australian Organic Geochemistry Conference, Fremantle, 4-7 December 2016
1 Geoscience Australia, Canberra, ACT 2 University of Rochester, Rochester, NY
Acknowledgment
Isotope and Organic Geochemistry Lab at GA • Junhong Chen • Ziqing Hong • Jacob Sohn • Neel Jinadasa • Prince Palatty
Industry for access to gas samples
Talk Outline
• Distribution of natural gases • composition and carbon isotopes
• Helium abundance and isotopes • sources • age control • other Noble gases
• Helium processing - from ‘wellhead to sales’
• molecular and isotopic fractionation
• Conclusions
0
50
100
150
200
250
300
to 0.01 0.01-0.02 0.02-0.05 0.05-0.1 0.1-0.2 0.2-0.5 0.5-1 >1
Freq
uenc
y
Helium (%)
Total frequency = 821
Helium distribution – GA samples • Over 1000 gases • 821 with measurable [He] > 0.0001% (1 ppm)
econ
omic
He
extra
ctio
n?
Amadeus Basin > 10% He
Location of natural gases for He isotopes
• 150 samples • 11 basins • Cenozoic to Cambrian
(source and reservoir)
0
1
2
3
4
5
1 2 3 4 5 6 7
ln (C
2/C3)
ln (C1/C2)
Amadeus
Bass
Bonaparte
Bowen
Browse
Carnarvon
Cooper
Gippsland
Gunnedah
Otway
Perth
Crust
oil cracking (2o) gas
kerogen cracking (1o) gas
modified after Tao et al. OG 2014
biodegradation
Natural Gas: mol. composition
-35
-30
-25
-20
-15
-10
-5
0
5
10
0 10 20 30 40 50 60 70 80 90
δ13 C
2 - δ
13C
3 ‰
C2/C3
Amadeus
Bass
Bonaparte
Bowen
Browse
Carnarvon
Cooper
Gippsland
Gunnedah
Otway
Perth
biodegradation
Natural Gas: mol. composition and C-isotopes
-25
-20
-15
-10
-5
0
5
0 5 10 15
δ13 C
2 - δ
13C
3 ‰
C2/C3
Amadeus
Bass
Bonaparte
Bowen
Browse
Carnarvon
Cooper
Gippsland
Gunnedah
Otway
Perth
biodegraded
Primary cracking
NSO cracking
Oil cracking
Abiogenic
Natural Gas: mol. composition and C-isotopes
Th-228
Re-224 Th-232
Re-228
Ac-228
1.4x1016 yr
5.8 yr
α
α
α
β
β
γ
6.1 hr
1.9 yr
3.6 dayRn-220
Po-216
α
α
55 sec
0.15 sec
γ
Po-212
Pb-212
Bi-212
10.6 hr
β
β
γ
61 min
0.3µsec
α
3 min
Tl-208
Pb-208β
stable
γ
U-234
Th-230 U-238
Th-234
Pa-234
4.5x106 yr
5.8 yr
α
α
α
β
β
γ
1..17 min
250,000 yr
80,000 yrRa-226
Rn-222
α
α
1602 yr
3.8 day
γ
Po-218
3 min
γ
α
Po-214
Pb-214
Bi-214
27 min
β
β
γ
19.7 min
160 µsec
Pb-210
22 yr
γ
Pb-206 Bi-210
Po-210
5 day
α
β
β138 day
γ
stable
Thorium decay
Uranium decay
perc
enta
ge o
f rad
ioac
tive
mat
eria
l rem
aini
ng 100
50
25
12.5
Number of half lives0 1 2 3 4
Radioactive Decay for U-238
4.5 9 13.5 18 billion yearstime for U-238
232Th
238Uranium decay
Rate determining step: t½ = 14.05 billion yr
Rate determining step: t½ = 4.5 billion yr
232Thorium decay
208Pb
238U
206Pb
4He (α particle) – crust and mantle sources
10
9
3He sources
• Mantle
• Crust
primordial 3He
3H Tritium (t½ = 12.3 yr)
6Li + n
Cosmic ray interaction with N & O
Helium sources R/Ra = 3He/4Hesample / 3He/4Heair ( 3He/4Heair = 1.4 x 10-6)
• Mantle • Crust
• Air
degassing
Meteoric water – Air Saturated Water (ASW)
3He/4He = 0.0000014 (R/Ra = 1)
3He/4He ~ 0.00000003 (R/Ra ~ 0.02)
3He/4He ~ 0.00001 (R/Ra ~ 8)
(R/Ra ~ 0.985)
Cosmic ray?
0.01
0.1
1
10
0.01 0.1 1 10 100
R/R
a
CO2 %
Amadeus
Bass
Bonaparte
Bowen
Browse
Carnarvon
Cooper
Gippsland
Gunnedah
Otway
Perth
Mantle
Crustal
He isotopes vs CO2
0.01
0.1
1
10
0.01 0.1 1 10 100
R/R
a
CO2 %
Amadeus
Bass
Bonaparte
Bowen
Browse
Carnarvon
Cooper
Gippsland
Gunnedah
Otway
Perth
Mantle
Crustal
He isotopes vs CO2
1.0E+05
1.0E+06
1.0E+07
1.0E+08
1.0E+09
1.0E+10
1.0E+11
1.0E+12
0.01 0.1 1 10
CO
2/3H
e
R/Ra
Amadeus
Bass
Bonaparte
Bowen
Browse
Carnarvon
Cooper
Gippsland
Gunnedah
Otway
Perth
Crustal CO2
Altered (CO2 loss)
Mantle CO2
Mantle CO2
Crustal CO2
CO2 loss CO2 loss
Age
He isotopes vs CO2
1.0E+05
1.0E+06
1.0E+07
1.0E+08
1.0E+09
1.0E+10
1.0E+11
1.0E+12
-20-18-16-14-12-10-8-6-4-20246810
CO
2/3H
e
δ13CO2 ‰
Amadeus
Bass
Bonaparte
Bowen
Browse
Carnarvon
Cooper
Gippsland
Gunnedah
Otway
Perth
He isotopes vs CO2 isotopes
1.0E+05
1.0E+06
1.0E+07
1.0E+08
1.0E+09
1.0E+10
1.0E+11
1.0E+12
-20-18-16-14-12-10-8-6-4-20246810
CO
2/3H
e
δ13CO2 ‰
Carnarvon
biodegradation
He isotopes vs CO2 isotopes
0.01
0.1
1
10
40 140 240 340 440 540
R/R
a
Age Ma
Amadeus
Bass
Bonaparte
Bowen
Browse
Carnarvon
Cooper
Gippsland
Gunnedah
Otway
Perth
Crust = 0.02Ra
high CO2 (44%) biodegraded : meteoric (Ra = 1) mixing
?
?
coal seam gas (later input)
He isotopes vs Age (source rock)
1
10
100
1000
10000
100000
40 140 240 340 440 540
4 He
ppm
Age Ma
Amadeus
Bass
Bonaparte
Bowen
Browse
Carnarvon
Cooper
Gippsland
Gunnedah
Otway
Perth
Air (5.2 ppm)
4He ppm vs Age (source rock) Magee and Mt Kitty
1E-06
1E-05
0.0001
0.001
0.01
0.1
1
10
0.01 0.1 1 10
20N
e/4 H
e
R/Ra
Amadeus
Bass
Bonaparte
Bowen
Browse
Carnarvon
Cooper
Gippsland
Gunnedah
Otway
Perth
Air/ASW
Mantle
Crust
Noble gas isotopes (3,4He 20,21,22Ne, 36,38,40Ar, 78,80,82,,83,84Kr, 124,126,128,129,130,131,132,134,136Xe)
Geological factors for high [Helium] (USA experience – straight from wellhead)
• He source - basement source has a larger source volume - hot (U, Th) sediment sources • Partitioning of dissolved He in pore water with migrating
gas phase - lower gas-water ratio higher [He] - old water: age of water in rock is more important than age of rock itself; look for old reservoirs with saline water • Shallow depth and low geothermal gradients - more He partitioned into gas at low P, low T and high salinity • Low maturity - less dilution by large volumes of generated hc gases • Migration front: at edges of prolific petroleum systems - first gas strips most He from pore water Modified from A. A. Brown, 2010. Formation of High Helium Gases: A Guide for Explorationists. Search and Discovery Article 80115
Helium from Liquefied Natural Gas (LNG) • Global (USA, Russia, Poland, Algeria, Qatar, Australia) 0.04 – 0.4% He • Qatar: 0.04% He - extraction is economic because of large volume
– He extracted from concentrated gases separated from LNG
• Australia: 3rd largest exported of LNG (2014) – projected to be No. 1 exporter
LNG plant - http://rasgas.com/Operations.html http://rasgas.com/Files/Operations/helium_qatars_journey.pdf
Qatar’s North Field holds around ¼ of known global helium reserves
Wheatstone
Greater Gorgon Pluto 2012
NW Shelf Venture 1989
Prelude
Darwin LNG 2005
Ichthys
Australian LNG
Australian Pacific 2015 Qld Curtis LNG 2014
Gladstone LNG 2015
http://www.appea.com.au/oil-gas-explained/operation/australian-lng-projects/.
Natural gases
Coal Seam Gas
Australia’s only commercial He extraction plant
Gas field He up to 0.28% CO2 8.3 ̶ 10.2% N2 3.1 ̶ 3.7% C6+ 0.2 ̶ 0.4%
Darwin LNG
modified from http://lnglicensing.conocophillips.com/Documents/OCP2.pdf
ConocoPhillips Optimized Cascade® LNG process: Darwin LNG (DLNG)
DLNG Rejected
N2
DLNG NGL
Bayu-Undan: DLNG feed gas
DLNG LNG
DLNG Rejected CO2
Darwin LNG (ConocoPhillips)
Darwin Helium (BOC)
Darwin LNG ‘feed gas’
- Rejected CO2 to incinerator
- NGL ‘condensate’
- LNG predominately methane
to Darwin Helium (BOC) - Rejected N2
Rejected N2
Feed gas
(‘tail gas’)
Darwin Helium ‘feed gas’: 3.0% He, 0.1% H2; 3.2% CH4, 93.6% N2 http://www.linde-kryotechnik.ch/1259/1260/1275/1645/1657/1647/1506.asp
99.999% He (P5)
Darwin Helium (BOC) plant
modified from Dan Wilson and Jeremy Armstrong, Darwin Helium (BOC), Oct’16
Helium extraction: isotopic fractionation
Bayu-Undan (He = av. 0.18%) (N2/He = av. 33)
R/Ra = 0.081
Rejected N2 / He-concentrate
(He = 3.0%) (N2/He = 31) R/Ra = 0.086
He-pure (He = 99.999%) R/Ra = 0.122
Bayu-Undan (av. C1 = 80.2%)
av. δ13C1 = -39.7‰ δD = -167.3‰
Rejected N2 / He-concentrate
(C1 = 3.2%; ̴0.1% total) δ13C1 = -46.7‰ δD = -159.4‰
∆δ13C1 ̴ -7‰
(isotopically lighter)
∆δD ̴ +8‰
(isotopically heavier)
Isotopic fractionations are consistent with the relative gas-liquid phase partitioning of CH4, 13CH4 and CDH3 Bigeleisen et al., Vapour pressures of isotopic methanes, J. Chem Phys. 47 4335 (1967)
LNG no expected
isotopic fract.
Conclusions • 1/5th of Australian gases have [He] > 0.05%
• potential for economic resource from LNG • commercial for Bonaparte gas extraction (av. 0.18% He; 3.4% N2) • ? others areas (low N2/He and high [He] in N2-reject gas)
• Amadeus Basin has highest [He] (>10 mole%); rel. small reserves • Crustal origin (4He) is dominant
• Amadeus Basin with highest radiogenic 4He • Notable exceptions: Otway with recent volcanism (3He), and Gunnedah (CSG) with intrusions(?) (3He)
• CO2 both linked and decoupled from He source • linked: e.g. Otway • decoupled: e.g. Carnarvon with carbonate decomposition and
precipitation • CO2 loss is pervasive: carbonate mineral precipitation?
• Increasing source/reservoir age leads to greater overprint by crustal 4He