CREATING VALUE FROM MONITORING
CO2 STORAGE PROJECTS
Professor Sally M. Benson
Co-Director, Precourt Institute for Energy
Stanford University

Where do we stand with CCUS today?
20 commercial projects, on
track for 24 by early 2020s ~35 Mt CO2/year CO2-EOR at 65 Mt
CO2/year, but mostly fromnatural sources
 Capture, compression,transport and storage doneat scale today

Annual Quantity of CO2 Captured andStored

Mt CO2/year

50
4540
35~10% growth rate
30per year25
201510501970
1990
20102030

The Decades Ahead for CCUS
500025%/yr

4000

Mt CO2/year~1-5 Gt/year by 2040 isneeded Rapid increases indeployment growth rates
required Double to triple historic
growth rates sustainedfor 2 decades


3000

2000

16%/yr

1000
Historical record02000

2010

2020

2030

2040

A Turning Point for CCUS
1970’s - present
Limited policy drivers
 CO2-EOR
 Sleipner Saline Aquifer Storage
project, Snohvit, In Salah, Illinois,Gorgon
 Many small scale pilots (<< 1 Mt)
 Growth rate of ~10%/year Learning by doing2020’s and beyond

Compelling need for CCUS
 Stronger policy drivers
 Growth rates of 20% or more
per year are needed 1 – 5 Gt/year by 2040
 Many commercial scale
projects 1+ Mt/yearConditions to support rapid scale-up
Strong policy support

Safety• Confidence of politicalleaders• No accidents, damage, orenvironmental harm

Cost

Regulatory compliance• Competitiveness with other
GHG reduction measures• Meet legal obligations

Public support

Technical Feasibility• Engagement andtransparency• Secure storage

Monitoring plays a critical supporting role forrapid scale-up of CCUS
Technical feasibility

SafetyCompliance with regulations• Ensure CO2 stays trapped in thestorage complex• Track the location of the CO2
plume• Limit pressure buildup to safe
levels to avoid geomechanicalimpacts• Identify and confirm storage
efficiency and processes• Model calibration andperformance confirmation• Assess the integrity of shut-in,
plugged or abandoned wells• Establish baseline conditions
from which the impacts of CO2
storage can be assessed• Detect and quantify surface
leakage• Detect and avoid unsafe levelsof micro-seismicity associatedwith CO2 injection• Design and evaluate
remediation efforts• Ensure effective injection
controls• Ensure groundwater protection• Evaluate interactions or impacts
with other geological resources:
for example nearby water, coal,oil & gas, mineral reserves orother geological waste disposal
operations• Accounting where monetarytransactions are involved suchas with carbon trading andemission tax or emission
reduction incentives

Creating value from monitoring
Benefits of monitoring >> costs
How much monitoring, for what purposes, using which technologies and at whatcost?
 Under which circumstances is it worth doing more than the minimum amount ofmonitoring required by regulatory requirements?
 Which types of monitoring provide the greatest value for the cost?
 If regulatory requirements provide the flexibility to choose between a variety ofoptions, how do you choose one approach over the other?
 What is of greater value, high spatial resolution or high temporal resolution?
Costs for monitoring vary over wide range depending on program.

What Needs to be Measured?
Parameters

Purposes for Monitoring

CO2 Concentrations

SafetySeismicity
Land Surface Deformation

Technical Feasibility

Surface and Downhole Pressure
CO2 Plume Location

Local Environmental Impacts
Or
GHG Regulatory Compliance

Ground & Surface Water Quality
CO2 flux into the atmosphereWhat Needs to be Measured?
CO2
concentrations

Infrared
spectrometer

Seismicity

GeophonesLand
surfacedeformation
Satellite
imagery

Surfaceanddownhole
pressure
PressuregaugesCO2 plume
location
Seismic
imaging

Groundandsurfacewaterquality

CO2 flux
into the air

Fluidsampling
and analysis

Eddy
covariance

Well logs

Surfacebased CO2
sensors anddata
analysis

Other
geophysicalimagingtechniques (EM,ERT, gravity)Gas
samplingand analysis

Fibernetworks

StrainsensorsDistributed
fiberSaturationlogs

Monitoring Requirements and Metrics
Where, when, how, and how
precisely?
 It depends…
 Regulations
 Risks
 Site constraints
 Technology availability
 CostMinimum requirements
 Wellhead and formationpressures Location of the CO2 plume Evidence that CO2 is not leaking
 Induced seismicity
 Worker safety related
measurements

Cost effective and reliable methods for meeting theminimum requirements are needed!

Monitoring Costs Are Important
Benefits of monitoring >> costs
Industry is concerned over high monitoring costs
 Long term stewardship – Post Closure Site Care -- is in impediment to final
investment decision Oilfield monitoring practices are much less stringent – raising questions about why
so much additional monitoring is needed for CCUS projects
 Conversion from EOR to storage projects results in significant additional
compliance costsWhat are the costs for monitoring?

Monitoring Costs (A Look Back to 2004)
Basic andenhanced
monitoring
program 258 Mt
injected Monitoring
during allphases of theprojectthrough site
closureSaline Aquifer 1

Saline Aquifer 2

EOR

ClosureOperationalPre-operational$0.30EOR/tonne CO2$0.28/tonne
CO2HRG

LRG$0.31 tonne CO2

Benson et al., 2004. Overview of Monitoring Techniques and Protocols for CO2 Storage Projects, IEAGHG Report.

($2004)

Example Costs for Monitoring

Woodbine formation example (NETLstorage cost estimator)
 96 Mt CO2 over 30 years 1.6 km deep

 3 injection wells
 Total cost of storage $9.3/tonne of CO2



Extensive monitoring program% monitoringcosts

 3-D seismic, VSP, eddy covariance 200 km2 seismic monitoring area

 In reservoir and above-zone monitoringwells (40 total) Cost of monitoring: $7/tonne

National Energy Technology Laboratory, FE/NETL CO2 Saline Storage Cost Model. U.S. Department of Energy. September 2017.

($2008)Lower Cost Monitoring Approaches andPackages are Needed
3-D seismic, the workhorse of CO2 monitoring is very expensive – comprising
the largest single cost for monitoring (and sometimes of the whole storageproject) Due to high costs for seismic monitoring, measurements are only madeperiodically (~5 years is typical for planning purposes)
 Seismic imaging is not suitable for all environments Reservoir or seal properties
 Proximity to other resources Difficulties in surface accessResearch to develop cost effective monitoring programs is needed.

Monitoring Program Gaps (NAS, 2018)
Mathematical approaches for data
assimilation and co-inversion.
 Strategies and technologies are needed
for adaptive monitoring program thatis site-specific and respond to changing
needs and conditions
 Providing real-time data for tracking
performance.
National Academy of Sciences, 2018.

Downhole Pressure Based MonitoringApproaches
In reservoir pressure monitoring forplume migration
 Above-zone pressure monitoring forleakage detection
 Applications in the Illinois Basin
Decatur SiteIn Reservoir Pressure Monitoring
17

Above Zone
Monitoring

In ZoneMonitoring

In Zone Pressure Monitoring
18

Westbay* MultilevelsystemPackerMonitoring zone
Pressure,
Temperature,Sampling

Hydrogeology

CCS

Studies emphasize
value of:Studies emphasize
the value of:• Vertical pressure
gradients• High-resolution
monitoring• Plume tracking

E.g. Mercer and Spalding(1991); Parker et al. (2006);
Fisher and Twining (2011)

PackerMultilevel Well Completions (product sheet)
http://www.slb.com/services/additional/water/monitoring/multilevel_well_system/well_completion.aspx• Reservoir structureDiagnostic Study: Can In Zone Measurements
Track Plume Migration?
19Strandli, C. W., & Benson, S. M. (2013). Identifying diagnostics for reservoir structure and CO2 plume migration frommultilevel pressure measurements. Water Resources Research, 49(6), 3462-3475.

Different Reservoir Structures
20

Isotropic
Anisotropic

Homogeneous

Heterogeneousxxxx

Homogeneous, isotropic scenario

Heterogeneous, isotropic scenarioDifferent Reservoir Structures
21

Isotropic
Anisotropic

Homogeneous

Heterogeneousxxxx

Homogeneous, anisotropic scenario

Heterogeneous, anisotropic scenario

Pressure Buildup Is Controlled By Reservoir
Heterogeneity and Isotropy
22

Homogeneous Isotropic

Heterogeneous Isotropic

Water inj. 12 months

CO2 inj. 12 months

Water inj. 12 months

CO2 inj. 12 months

Radial position (m)Radial position (m)Radial position (m)Radial position (m)Delta P (MPa)

Homogeneous Anisotropic

Heterogeneous Anisotropic

Water inj. 12 months

CO2 inj. 12 months

Water inj. 12 months

CO2 inj. 12 months

Radial position (m)Radial position (m)Radial position (m)Radial position (m)Delta P (MPa)Pressure Transient Behavior Diagnoses Height of thePlume23

Delta P/Delta PZone 1

Zone 3

Zone 1

Zone 4, Zone 5
CO2 inj.

Zone 6Time (months)

Pressure buildups deviate
from the behavior for waterinjection
 Pressure decreases indicatethat the CO2 plume has
passed above themonitoring zoneWater inj.

Pressure Data from Monitoring Wells
Three Diagnostics

Deeper• Magnitude of pressurebuildup• Amplitude of response
to injection fluctuations• Decline in pressurebuildup over time

Shallower
Strandli and Benson, IJGGC, 2013.

History Matching of Pressure Data
25

From Strandli et al, 2014

Plume Migration Predictions
4 Months

8 Months

27

Measured CO2 Saturation Agrees Well WithPredictions

Measured CO2 SaturationCouëslan et al. (2014)18 Sept 2015

Automated Inversion of Pressure Data
BHP

Z2

Z1

0.8

1320.8

MPa

MPa

MPa

0.6
0.4

0.6
0.4

10.2
0.2
0000100

200

300

400

500

600

700

800

0100

200

300

400

500

600

700

0800

100200

300

400

Days

Days

Days

Z3Z4Z50.3

500

600

700

800

500

600

700

800

0.15

10.25
0.60.2

MPa

MPa

MPa

0.8

0.15

0.40.10.20.05

0.050000100200300

400

500

600

700

800

0100200300

Days

0.1

0.1

0.08

0.08

500

600

700

800

0.040.020.02
100200300

400

Days

500

600

700

800

100200300

400

Days

Z8Z90.1
Obs
PSO best
f mincon
Weighted without Z7

0.05

000Days

0.06

0.04

0400

MPa

0.12

MPa

MPa

Z6
0.12

0.06

0.1

00100

200

300

400

Days

500

600

700

800

0100

200

300

400

Days

500

600

700

800

D. Cameron andBenson,
in preparation.

Automated Inversion Plume
Migration Predictions
Optimal layer perm.
1860

CO2 plume after
4 monthsCO2 plumeafter 1 year

Depth (m)

1880

1900

1920

1940

1960

-20log10 kx

2D. Cameron and Benson, in preparation.

Above-Zone Pressure Monitoring
5Katz and Coats (1968)

CO2 Sequestration:
Chabora (2009)
Nogues et al. (2011)
Zeidouni et al. (2011)
Tao et al. (2012)

Gas
Storage Reservoir

Katz (1971)

Above Zone Pressure Monitoring for Leakage
Monitoring wells• Where is the leak?
• How much is leaking?
Leak location

CO2 plume[Cameron, D. A., Durlofsky, L. J., Benson, S. M, 2016]

Heterogeneous Model andMonitoring Wells
100 km2

Monitoring wellsk (md)

Simulation model

Injection wells

Five Scenarios Tested
500-yr CO2leakage

30-yr brineleakage

True 1

0.7%

0.3%

True 2

3.3%

0.5%

True 3

7.5%

8.5%

True 413%

8.3%

True 523%

7.8%

Simulations Indicate Above Zone Monitoringis Highly Effective• Leak detection occurs quickly (< 1 year)• Leakage location detection requires 3 wells

34

Fluid Leakage: 30 years

500 Year CO Leakage
2

Final thoughts
Benefits of monitoring >> costs


Difficult to quantitatively assess benefits for monitoring Financial risk mitigation from leakage or damages
 Societal engagement and transparency
 License to operateMany monitoring techniques are available
 Need to develop integrated packages with highest value While, keeping costs lowReal time awareness of project status a priority
 Permanently emplaced arrays of sensors (pressure, seismometers)
 Automated data inversion and interpretation