Monitoring a CO2 Storage Tor Fjæran – President Director Statoil Indonesia Seminar on Evaluation of CO2 Storage Potential, ITB Bandung, 11- 12 December 2012

Classification: Internal 2012-12-06

Contents

• Why, where and when

• Regulations

• How to monitor

− Monitoring technologies

− common methods

− Statoil’s experience

− what is measured and what can be achieved

• Examples from Statoil’s current CO2 storage sites

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Why monitor?

• Authority requirements

Regulations

License to store CO2

• Storage reservoir performance (injectivity, capacity)

• Preserve investments

• Climate quotas, accounting

• Operational safety

• Assure no negative impact on humans, animals or plants

• Real contribution to climate change mitigation

- The risk for any significant leakage is relatively low. - Verify that the CO2 stays underground. - Reservoir management important in optimizing the storage performance.

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European legislation

• European Union directive (2009/31/EC), main requirements :

• “Member States shall ensure that the operator carries out monitoring of the injection facilities, the storage complex (including where possible the CO2 plume), and where appropriate the surrounding environment for the purpose of:

− a) comparison between the actual and modelled behaviour of CO2 and formation water in the storage site

− b) detecting significant irregularities

− c) detecting migration of CO2

− d) detecting leakage of CO2

− e) detecting significant adverse effects for the surrounding environment, including in particular on drinking water, for human populations, or for users of the surrounding biosphere

− f) assessing the effectiveness of any corrective measures taken pursuant to Article 16

− g) updating the assessment of the safety and integrity of the storage complex in the short- and long-term, including the assessment of whether the stored CO2 will be completely and permanently contained

http://ec.europa.eu/clima/policies/lowcarbon/ccs/implementation/documentation_en.htm

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• Injection well(s)

Monitoring targets:

• Site specific, dependent on geology, onshore/offshore, existing wells, etc

“Old” well Injection well

Degree of precision differs as large areas relies on «remote sensing» methods

• Main plume development in the storage formation

• Overburden

• Seabed and shallow sediments (benthic zone)

• Pre-existing well(s)

Where to monitor?

Important in each case to establish:

− Size of area to monitor?

− Simulations to estimate most likely CO2 migration pathways

− Need for observation well(s)?

Implication on technology / timing / economics

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“Old” well Injection well

What to monitor?

• Injection well − Composition, impurities − Rate of injection − Pressure (wellhead, downhole) − Temperature (wellhead, downhole)

• Observation well (?) − Downhole sensors − Fluid sampling

• Surface measurements − Fluid and gas sampling − Remote sensing (geophysics)

• 4D seismic • Microseismic • Gravimetry • Surface elevation • Electromagnetic

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When to monitor?

Establish baseline.

Early enough to pick up natural

variabilities

~ 25-50 ? ~ 25 ? -1-2 ? 0 Years

Injection phase Closure Post-closure

BASELINE

Pre-injection Phases

Determined by authorities’ requirement

Regular monitoring.

Closure monitoring.

Map situation at injection

halt.

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How to monitor? 2D surface seismic 3D surface seismic

Airborne EM Airborne spectral imaging

Boomer/Sparker profiling Bubble stream chemistry

Bubble stream detection Cross-hole EM

Cross-hole ERT Cross-hole seismic

Downhole fluid chemistry Downhole pressure/temperature

Ecosystems studies Eddy covariance

Electric Spontaneous Potential Fluid geochemistry

Geophysical logs Ground penetrating radar

High resolution acoustic imaging IR diode lasers

Land EM Land ERT

Long-term downhole pH Microseismic monitoring

Multibeam echo sounding Multicomponent surface seismic

Non dispersive IR gas analysers Satellite interferometry

Seabottom EM Seabottom gas sampling

Seawater chemistry Sidescan sonar

Single well EM Soil gas concentrations

Surface gas flux Surface gravimetry

Tiltmeters Tracers

Vertical seismic profiling (VSP) Well gravimetry

Overview (with links) to IEA GHG / BGS’s* «Monitoring toolbox»:

*) BGS = British Geological Survey

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Technique Measurement parameters Example applications

Time-lapse (4D) seismic

P and S wave velocity Reflection horizon Seismic amplitude attenuation

Tracking CO2 movement in and above storage formation

Passive seismic Micro seismic

Location, magnitude and source characteristics of seismic events

Development of microfractures in formation, caprock CO2 migration pathways

Electrical and electromagnetic

Formation conductivity Electromagnetic induction

Track movement of CO2 in and above the storage formation Detect migration of brine into shallow aquifers

Time-lapse gravimetry

DensityGravity changes caused by fluid displacement

Detect CO2 movement in or above storage formation CO2 mass balance in the subsurface Indications of CO2 dissolved in formation water

Land or seafloor surface deformation

Tilt Vertical and horizontal displacement using interferometry and GPS Echo sounding, side scan sonar

Detect geomechanical effects on storage formation and caprock Locate CO2 migration pathways

Surface geophysical monitoring tools What is measured?

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Method SLEIPNER SNØHVIT Year of injection start: 1996 2007

Depth [m] top reservoir: 800-1100 ~2600

Time-lapse 3D seismic 1994(B)-1999-2001-2002-2004-2006-2008

2003(B)-2009-2011

Time-lapse gravimetry 2002-2005-2009 2007(B)-2011

Wellhead (WH) and downhole (DH) pressure and temperature WH ‘continuously’ WH and DH

continuously

Control-Source ElectroMagnetics (CSEM) 2008 -

Microseismic - -

Land or seafloor deformation measurements Se below -

Multi-beam echo sounder 2006-2011 -

Monitoring at Statoil’s operations in Norway

(B) = Baseline survey

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Experiences from Sleipner

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Utsira Fm.

1994

2001

2008 CO2 plume in map view

Time-lapse seismic data

2008-1994

Sleipner – 4D seismic

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Depth [m]

Mozaic of side scan sonar data

Sleipner – Seabed Survey Multibeam echo sounding

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Observed in-situ CO2 density from gravity measurements: 720 +/- 80 kg/m3

… assuming no dissolution into the formation water …

Sleipner – Gravimetric monitoring

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Sleipner CSEM - survey 2008 • One line of CSEM data acquired across

CO2 plume • 27 receivers at 20 locations –

− 500m between receiver locations − 50m between “doubled” receivers

• Data quality is good, but:

• Possible interference from pipelines etc.

• Data processing and interpretation challenging

• No baseline

• Still no clear conclusion on the effectiveness of CSEM on Sleipner

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Experiences from Snøhvit

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CO2 injection

CO2 Injector

Nordmela

Stø

Tubåen

New perf.

Snøhvit CO2 injection

Main segment with gas producers

X

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Top Fuglen Fm.

Base Tubåen Fm.

CO2 injection well

CO2 injection well

baseline 2003 repeat 2009 difference

0.5 km

Increasing amplitude

Amplitude changes

Monitoring at Snøhvit – Seismic

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2009 2009-2011

Stø3-6

Top Reservoir

Stø2

Nordmela

perf Top CO2

Base CO2

Monitoring at Snøhvit – Seismic

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Lessons learned from Sleipner and Snøhvit • Single wells have successfully injected 0.4-0.9 million tons of CO2 per year.

• Surface geophysical and well pressure monitor data give rich information on the storage behaviour: Dynamic modelling is better constrained, but still challenging.

Indicates strong gravity segregation and minimal dissolution

• The actual CO2 plume development has been strongly controlled by geological factors which we learned about during injection.

• High-quality monitor data lowers the detection threshold for any potential leakage: 4D seismic monitoring confirms no leakage into the overburden.

• Detailed site characterization, reservoir monitoring/modelling and well solutions have allowed us to quantify the storage capacity and field performance: Gives a good basis for scoping and optimizing future projects.

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Summary and conclusions • Regulation authorities states that the storage operator is responsible for

assuring safe storage of CO2 − Plan, carry out and report the results of monitoring, and undertake corrective measures if a an

alarming situation should occur

− Continued research will improve precision and quantification

− Long term liability will be an issue for negotiation with the authorities

• Planning for Monitoring, Verification and Accounting (MVA) of a new CO2 storage site:

− The monitoring program will be site specific

− Important to establish a good baseline

− Time-lapse 3D seismic is still the key technology. Other remote sensing tools will be supplementary. Will loose their usability with increasing depth

− The storage operator will select fit-for purpose methods with satisfactory cost vs benefit.

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Tor Fjaeran President Director, Statoil Indonesia tof@statoil.com www.statoil.com

Thank you

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