Risk assessment andregulation of aquifer storage ofcarbon dioxide
19 November, 2007
Takashi OHSUMIRITERemote CO2 Release Scenarios
Field CSequestration
Field ASeabedSequestration
Field BSea current
Old pockmark“Wytch hole”
Leak off

Diffusion
Escape tosurface via
aquifer outflow

WAG allows
Aquifer flow
through trappedgas

Accumulations
In mudOver pressurise
shallower formation

WAG

OWC tilt

Well plug
Abandonedwell

Pressure
inducedfractureDiffusion& flow

Mineralisation

Freegas P, TGSGIAquiferflow at shallower
depthsCap goodfor oil butnot gas
Shale

Diffusion
Aquifer flow
Dispersive
mixingShaleWhat has been done in the R&D
projects for risk management ?
A release scenario was presented at “Risk Assessment
Workshop” held in British Geological Survey in May 2002.
From outside Europe, RITE reported on the risk management
at Nagaoka Project:- monitoring on CO2 concentration around wellhead- monitoring for microseismicity- caprock integrity evaluation using the actual core sample

Injection Test
Storage Tank

Lorry

PumpHeater

a12-m section
selected for
injection zone
in aquifer with60 m in thickness

DIMENSION:DIMENSION:
oneone injection
injection wellwell
three
three observation
observation wells
wells
duration
duration ofof injection:
injection: 1.5
1.5 years
years
total
total amountamount ca
ca 10,000
10,000 tonnes
tonnesinjection
injection rate:rate:
20
20 tonnes
tonnes per
per day
day tilltill March
March 2004
2004
4040 tonnes
tonnes per
per day
day fromfrom April
April 2004
2004

1,100mimpermeable zone (caprock)with thickness of 140 m
CO２
TargetAquifer

40〜120ｍ

Injection Test
Surface
Surface monitoring
monitoring
atat wellhead
wellhead

Storage Tank

Lorry

Pump
Heatera12-m section
selected for
injection zone
in aquifer with60 m in thickness

1,100mimpermeable zone (caprock)with thickness of 140 m
CO２Target
Aquifer

40〜120ｍ

Real-time monitoring of microseismicity at Nagaoka test site
地中に埋設

1.6m x 1.6 m
横1.6m×縦1.6m
signal to monitoring station
三脚2.2 m deep

材料

高さ
2.2m

単管パイプ
1.6m×13本(9本)
2.2×4本直交クランプ
24個
自在クランプ
4個

滑車
振動吸収材

ハイドロホンケーブル
Cable
from hydrophone downhole

Triggering level was
set to 1 gal ( = 0.1% FS)

コンクリートベース

hydrophones
ハイドロホン(受振部)孔内水位約GL120ｍ

water level in well : GL-120 m

Core samples form target aquifer zone
recovered from injection wellNo.4 1095m - 1100m

Microscopic image of siltstone sample
Volcanic ash

QuartzVolcanic
Coloredash
minerals

QuartzOrganic vein

Siltstone as caprock of Nagaoka injection test site

Supercritical CO2 treatment on powder samples
Non-treated
Combustiongas
analysis

CO2 treatment
Pulverizedsample

Batch typeautoclave

C and N
contents
Organic CN
analyzer

Pressure : 10 MPa
Temperature : 50, 100, 150℃
Treatment period : 10, 20, 30 days

Pore radius distributions
Non-treated

50℃ 30 days

150℃ 30 days

risk assessment & regulation- risk communication International discussion on
the potential leakage onto sea-floor bottom and theconsistency in the existing framework of marine pollution
control
started in fall of 2004 andfinalized in fall 2007.
On 8 November 2007, CO2-WAG was adopted in the London
Protocol meeting.
What is the start point from now on, in the risk communicationof CO2 underground geological storage?

End points of the risk assessment
Time & space mode of migration of CO2 to thesurface environments and its effect are to be
examined in terms of:- human health- economic damage (infrastructure…)- ecosystem impact

To prevent ecosystem alteration is also theobjectives of marine pollution control system
including London Convention
The introduction of the permit system of offshore
geological CO2 injection to the London Convention
Scheme is justified by the fact that CCS could
mitigate the future acidification of marineacidification.
The important outcome was that “themitigation/remediation measures in case thatconcerns on the potential leakage are emerged
are included as a component of permit conditions”.