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

Helium (3He, 4He)

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)

Helium Processing: from wellhead to sales gas

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