Tracing CO2 geological sequestration processes with noble gas isotopes
Zheng Zhou, University of Manchester
Outline
• Introduction
• Identifying and quantifying natural CO2 sequestration processes over geological timescales:
The Jackson Dome CO2 Deposit, USA
• Predicting CO2 EOR and geological sequestration processes with artificial noble gas tracers:
Salt Creek, USA
• Summary
Introduction
Noble gases in natural gas reservoirs
– Three sources
– Conservative in the
Subsurface
– Isotopically distinct
– Ideal tool to quantify
the interaction and
origin of fluids
– Dating fluids
(After Ballentine and O‘Nions, 1994)
Geological setting
Schematic cross section
The Jackson Dome CO2 Deposit, USA
The Jackson Dome CO2 Deposit, USA
• Groundwater is responsible for more than 75% of CO2 loss
0.004 0.008 0.012 0.016 0.020
1x109
2x109
3x109
4x109
5x109
CO
2/3
He
20Ne (ppm)
South Pisgah
Denkmann 1
Holly Bush Creek
The Jackson Dome CO2 Deposit, USA
• Gas stripping and re-dissolution model can explain observed data
• Data are consistent with between 100% and 24% CO2 saturation of the groundwater into which re-dissolution occurs
0.6 0.8 1.0 1.2 1.4 1.6
1x109
2x109
3x109
4x109
5x109
6x109
South PisgahC
O2/3
He
20Ne/
36Ar
20% CO2 saturation
60% CO2 saturation
80% CO2 saturation
40% CO2 saturation
Holly Bush Creek
Rayleigh
dissolution
0% saturation
Rayleigh dissolution 100% saturation
GGS-R model
Denkmann #1
The Jackson Dome CO2 Deposit, USA
• Combined noble gas and stable isotopes distinguish between and quantify different mechanisms of CO2 removal from natural CO2 gas deposits
Salt Creek Oil Field, USA
Injection and monitoring wells
Distances: 18-37: 180m 16-37: 160m 28-37: 230m 30-37: 270m
Injection well 37 Production wells 16, 18, 28 and 30
18
30
16
28
37
Salt Creek Oil Field, USA
Tracer injection system on site
N2 cylinder Water reservoir tank
Isotope spike tank
Pressure gauges
Strain gauges
HPLC pumps
Salt Creek Oil Field, USA
Tracer injection
06/09/2010
16/09/2010
26/09/2010
06/10/2010
16/10/2010
26/10/2010
05/11/2010
0
10
20
30
40
50
3H
e/4
He
(R
/Ra
)
Date
Helium
0
10
20
30
40
50
12
9X
e/1
32
Xe
Xenon
Injector
Tracer Injection Period
13 Sep. --- 23 Sep.
Tracers 2 litre (STP) 3He 2 litre (STP) 129Xe
Calculated ratios 3He/4He ~ 107 Ra 129Xe/132Xe ~ 24
CO2 injection rate: 1285 mcf/day
Background ratios: 3He/4He = 0.04 Ra 129Xe/132Xe = 0.98
Salt Creek Oil Field, USA
Tracers in monitoring wells
06/09/2010
16/09/2010
26/09/2010
06/10/2010
16/10/2010
26/10/2010
05/11/2010
-0.5
0.0
0.5
1.0
1.5
2.0
3H
e/4
He
(R
/Ra
)
Date
Helium
Producer 18
0
10
20
30
40
50
60
70
80
90
100
Te
mp
era
ture
(F
)
Temperature
Tracer Injection Period
13 Sep. --- 23 Sep.
o Tracers are shown in monitoring wells a short period after injection o 3He/4He ratios are lower than spiked ratio o Spike breakthrough correlates with well temperature
Summary
• Noble gases can be used to obtain physical models to describe gas – mineral – fluid interaction
• These models provide quantitative understanding of geological CO2 sequestration processes
• Noble gases together with other gases can be used in hydrogeological modelling and studying CO2 EOR and sequestration processes