Geoelectric Crosshole andGeoelectric Crosshole and · PDF fileGeoelectric Crosshole andGeoelectric Crosshole and Surface-Downhole Monitoring: ... penetration range. (b) ... Resistivity

Geoelectric Crosshole andGeoelectric Crosshole and Surface-Downhole Monitoring:

First Res lts

i li 1 h 1 2 li h id b 1

First Results

Dana Kiessling1, Hartmut Schuett1, 2, Cornelia Schmidt-Hattenberger1, Frank Schilling1, 3, Erik Danckwardt4, Kay Krueger1, Birgit Schoebel1, and CO2SINK Group2 p(1) Helmholtz Centre Potsdam, GFZ German Research Center for Geosciences, Germany(2) now at StatoilHydro ASA, Stavanger, Norway(3) now at: Institute for Applied Geosciences, Universität Karlsruhe, Germany(4) Institute of Geophysics and Geology, University of Leipzig, Germany

IEA GHG - 5th Monitoring Network Meeting, June 2-4, 2009 / Tokyo

( ) p y gy, y p g, y

Outline

Introduction

Combined Downhole and Surface-Downhole Concept

I.

II.

Preliminary Results

Conclusions

III.

IV.

OutlookV.

CO2SINK … CO2 Storage by Injection into a Natural Saline Aquifer at Ketzin


Universität Leipzig

I. Introduction

N

Helmholtz Centre Potsdam, GFZ German Research Center for Geosciences, CO2SINK Group

Injection WellKtzi 201

50 m

Ktzi 201

CO Tanks

Ktzi 202Ktzi 200

September 2008

CO2 Tanks


first European onshore CO2 storage at Ketzin

I. Applications for Geoelectrics

hydrological questions:prospecting of groundwaterprospecting of groundwaterboundary of saline and freshwater…

investigation of structures and processes (contrasts in resistivity!)

CO2 plume monitoring

R fReferences: Ramirez, A. L., Newmark, R. L., Daily, W. D.,2003. Monitoring Carbon Dioxide Floods Using Electrical Resistance Tomography (ERT): Sensitivity Studies. Journal of Environmental and Engineering Geophysics, Volume 8, Issue 3, pp.187–208.g g p y , , , pp

Christensen, N. B., Sherlock, D., Dodds, K., 2006. Monitoring CO2 injection with cross-hole electrical resistivity tomography. Exploration Geophysics 37, pp.44-49.


II. Geoelectrical Monitoring Concept

Date injected CO2

Last facility tests and preparation 20/06/2008

Start of CO2 Injection 30/06/2008 0 t

Arrival of CO2 at 1st observation well 15/07/2008 531 t

Arrival of CO at 2nd observation well 20/03/2009 about 11000 tArrival of CO2 at 2nd observation well 20/03/2009 about 11000 t

today 26/05/2009 about 15500 t

Drilling of the wells2007

Ktzi 200 201 202

Start of CO2 Injection2008

Ktzi 201

May July August June 30time



taper pin

ring-shaped steel electrode

taper pin

insolated casingelectrical

cable(two-component material consisting of an epoxy matrix and a Polyphenylene Sulfide (PPS) membrane)Sulfide (PPS) membrane)


II. Geoelectrical Monitoring Conceptfour-point-method Crosshole Measurements

IU

C1 C2P1 P2

current injected between 2 electrodes C1, C2

potential measured between 2 electrodes P Pa … apparent resistivity

apparent resistivity

increasing of resistivity with CO injection

a = k R = k . . UI

potential measured between 2 electrodes P1, P2 k … geometric factorR … resistanceU … voltageI current


increasing of resistivity with CO2 injection I … current

II. Geoelectrical Monitoring Concept geophysical monitoring of the migration of the injected CO2 by using seismic and

geoelectric measurements

different methods = more information &risk reduction

geoelectrical methods are more sensitive atintermediate and high gas saturation(above 20 %) than seismic methods

Wilt & Alumbaugh 2006

geoelectrical measurements are relativelyeasy to deploy permanently and operationallysimpler than seismic methods

hi h i i d ffi i Wilt & Alumbaugh, 2006 higher repetition rate and more cost-efficient but: lower resolution

investigation of the feasibility of the geoelectrical monitoring of the CO2 migrationi t th li if i K t i


into the saline aquifer in Ketzin

Method Physical quantity

Criterion Depth range Lateral extent around Ktzi201

Maximum SCO2

Remarks

Where we are: Overview (status CO2SINK 12th proj. m. Feb. 2009 / Phase of data matching

quantity considered [m] [m]

SCO2

reservoir modeling

CO2saturation

SCO2 ≥ x (a) 635 – 645

(b) 645 – 655

40

40

40

50% No absolute depth scale in figure; depth estimated.

Q: Does the(c) 665 – 67540 Q: Does the

model reflect the reservoir 1:1 or just statistically?

RST CO2saturation

SCO2 ≥ x (a) 625 – 627

(b) 630 633

n/a 60% Very short penetration range.saturation (b) 630 – 633

(c) 634 – 642

(d) 645 – 648

DTS temperature deviation from 625 – 675 n/a n/a Very short DTS temperaturelinear trends penetration range.

ΔT ≈ +5.0 °C

crosshole seismic

signal correlation

correlation or anticorrelation ≥ x

(a) 644 – 652

(b) 657 – >662

n/a

n/a

? Sources and receivers in Ktzi200 and Kt i202!≥ x

(c) 640 – 67280 (between Ktzi200

and 202)Ktzi202!

ERT resistivity resistivity increase ≥ x

(a) 600 – 615

(b) 630 – 655

15

25

20 (in the middle

50%

(Archie estimate)

(a) artefact?

(c) very likely artefact


(c) 700 – 71520 (in the middle betw. 200 and 201)

estimate)


Lab data before CO2

Lab data after CO2

difference CO2 saturation from model

Laboratory results:

2 2

Ktzi202_B2-3b

[m] 0.52 1.75 +240% 50% Archie

Ktzi202 B3 1bKtzi202_B3-1b

[m] 0.47 1.40 +200% 46% Archie

Kummerow et al., 2008 available data (lab logs Archie reservoir modeling) available data (lab, logs, Archie, reservoir modeling)

suggest a bulk CO2 saturation of 50% which corresponds to a resistivity increase of 200% to 300%

Archie formula: = w a -m Sw-n

without any additional data:a = 1, m = 2, n = 2 (standard for sandstone)


a 1, m 2, n 2 (standard for sandstone)brine resistivity: w = 0.037 m

Resistivity logs and ERT crosshole data (baseline)

Ktzi201Ktzi200

HRLA/SLBBLM


Comparison of inverted data with the trend of logs give indications for parameter settings


50% CO2↓

Ketzin resistivity model – feasibility study : synthetic resistivity model

~ 4.0 m layer635-650 m depth

↓

+ 300 %

x und y slices of resistivity changes

changes in resistivity are expected

z slices of resistivity changesKtzi201

Ktzi200 Ktzi202what we expect:

3 layers, middle layer is saline sandstone aquifer CO2 effect from Archie for SCO2

= 50 %

x und y slices of resistivity changes

r ≈ 30 mx

z slices of resistivity changes

2 CO2 resistivity range for inversion: 0.5 m (min ) to 4 m (max) Low resistivity environment and low resistivity contrast !

iti it i th iddl d i th t l ft ( l t d )


no sensitivity in the middle and in the top left corner (no electrodes) ”investigation range” around the wells: about 30 m

II a. Crosshole Measurements

VERA

Vertical El t i lElectrical Resistivity Array

45 permanent electrodes15 electrodes per wellelectrode spacing ~ 10 minstallation depth ~ 590 to 735 m

mudstone

sandstone

siltstone


II a. Crosshole Measurements

monitoring of CO2 migration between i j ti ll Kt i201 d th tinjection well Ktzi201 and the two observation wells Ktzi200 and Ktzi202

using dipole-dipole configurations, bipole bipole configurations includingbipole-bipole configurations including cross-hole configurations and user defined configurations having one current and one potential electrode in each well

used current: 2 5 A max

equipment: GDP-32II, ZT-30, MX-30 (Zonge, USA)

used current: 2.5 A max. used channels: 15 (for potential registration) measured potential: 50 V to 100 mV


continuous measurements since start of injection

II b. Surface-Downhole Concept

electric power source TSQ-4 (Scintrex Limited, Canada)

I = 4 – 18 AU = 500 – 1300 V

Texan-125 (Refraction


16 dipoles at the surface for current injection (C1C2)dipole length: 150 m, r1 = 800 m, r2 = 1500 m

e a 5 ( e act oTechnology Inc., USA)


current injection at surface

timeelectric power source TSQ-4 (Scintrex Limited, Canada)

I = 4 – 10 AU = 900 – 1300 V

potential registration Downhole

Texan-125 (Refraction


timee a 5 ( e act o

Technology Inc., USA)


l i l ( ll d )geoelectrical (yellow dots)and seismic (red lines and light blue grid)survey at the surface


Study of pre-inversion data(3)

Real field data Engineers‘Toolbox

R = UI

R … resistance

k R k U apparent resistivity

geometry

inversion

a = k R = k . .I

a … apparent resistivity

• Automized evaluation of field inversion

resistivity

data sets by digital filtering according relevant criteria

• Skip of defective data / enlarge


… resistivity• Skip of defective data / enlarge the set of applicable data

Quality check of data

Skip !


o.k.

III. Preliminary Results

Injection WellKtzi201

Ktzi200 Injection WellKtzi201

Ktzi200

Geoelectric Crosshole Measurements:

E W-590

-635

E W

-650salineaquifer

CO2-Injection

50 md h

-73550 m50 mdepth

in m 21.06.2008Baseline

50 m

30.10.20083400 t CO2

EarthImager, AGI


Preliminary inversion results of crosshole measurements

time lapse difference method

base line June 21 2008CO2injection base line June 21, 2008

(EarthImager, AGI)injection point

2D X-slice / area near boreholes under consideration

5300 t(Dec 11, 2008)


16.10.2008, trial 1,9 it./ RMS=4.2% / L2=0.3

22.10.2008, trial 1,9 it./ RMS=3.4% / L2=0.2

23.10.2008, trial 2,9 it. / RMS=10.8% / L2=0.8

28.10.2008, trial 2,7 it./ RMS=3.8% / L2=0.2


BHP BHT Cross-hole data from regular storage operation

Sensitivity analysis of measurement fi ticonfigurations

Electrode configuration evaluation• Forward modelling (e.g. finite elements, finite differences) with different

electrode configurations (dipole-dipole, bipole-bipole etc.)• Modelling on homogenous resistivity distribution• Modelling on homogenous distribution with local perturbation• Comparison of synthetic model response• Evaluation of possible resolution within synthetic pre-inversion datasets


THOUGH2, V2: homogeneous aquifer,homogeneous permeability, circular

CO2 distribution dependent on theheterogeneity of permeability

Joint interpretation with other modeling work

IW OW1

migrationheterogeneity of permeability

Perm., uncorrelated

Sand-

531 t CO2

injected

Resolution eser

voir

heig

ht

Sandstone

Resolution of crossholeGeoelectrics:

5 m

Re

Detected front of CO2:

35 m

oir h

eigh

t

model datamodel dataR

eser

vo


(U. Lengler, 2009)

III. Preliminary ResultsCombined Surface-Downhole Concept : Fundamentals

schematical: 2D dipole-dipole-configuration (CCPP)S =

da

d

C1C

C1C

P1

C2 C2 S+

S-: = S+: = P2

P1P S

S : = a

negative sensitivity:increasing in resistivitylead to

S : = a

positive sensitivity:increasing in resistivitylead to

P2 S-

sensitivity

lead to an decreasing in apparent resistivity(measured)

lead to an increasing in apparent resistivity(measured)


(S. Friedel, 2000)

III. Preliminary ResultsCombined Surface-Downhole Concept : Fundamentals

equally valid for Surface-Downhole Principle (CCPP)S =

da

d

C1C2

Injection WellKtzi201C1C2

Injection WellKtzi201

Injection WellKtzi201 S+

P1COP1

S+: = a

P2

S-: = a

CO2P2S-

sensitivity

an increasing in apparent resistivity(measured)

a decreasing in apparent resistivity (measured)is caused by an increasing in resistivity in another direction (in range of negative sensitivity)


is caused by CO2(E. Danckwardt, 2001)

III. Preliminary ResultsCombined Surface-Downhole Concept:

ti > 1 i i i t i ti it COratio = 1: no changes in apparent resistivity a

(C1C2 at the surface)

d

ratio > 1: increasing in apparent resistivity = CO2

ratio < 1: no CO2-caused changes in this direction

S = da

d


Repeat November 2008: 4500 t CO2Baseline April 2008: 0 t CO2Electrodes 16-30 in Ktzi201 (P1P2 in the borehole)


16 dipoles at the surface (dipole length: 150 m)

Combined Surface-Downhole Concept:

r1 = 800 mr2 = 1500 m


in m


… ratio > 1: CO2

… ratio < 1: no CO2-caused changes in this direction

Combined Surface-Downhole Concept:

… ratio = 1: no changes in apparent resistivity a

current electrodes (C1, C2): 16 dipoles at the surface

i l l d (P P ) potential electrodes (P1, P2):Ktzi201 (at sandstone aquifer/ depth of injection)

a1 from Repeat November 2008: 4500 t CO2

a0 from Baseline April 2008: 0 t CO2changes in a:


a0 p 2

located in z = -635 m (top of sandstone aquifer)

IV. ConclusionCombined Surface-Downhole Concept:

… ratio > 1: CO2

… ratio < 1: no CO2-caused changes in this direction

… ratio = 1: no changes in apparent resistivity a

CO2 – migration trend:

NW-SE-direction

changes in a: BUT NO information about lateral CO2 migration progress!


located in z = -635 m (top of sandstone aquifer)

IV. Summary and Conclusion

Geoelectrical monitoring at Ketzin:

deepest permanent downhole electrode array (from 590 to 735 m) deepest permanent downhole electrode array (from 590 to 735 m) using “smart-casing” technology part of a monitoring concept which integrates Geophysics, Geochemistry, Microbiology

Crosshole Geoelectrics can resolve an increase of the electrical resistivity caused by the CO2 injection, however, small-scale fingering effects in CO2 migration could not b d li t d b th VERA t

geoelectrical Crosshole and Surface-Downhole Measurements for monitoring CO2: it works in general, it has to be further developed

be delineated by the VERA system

monitoring CO2: it works in general, it has to be further developedbut some problems were underestimated at the beginning of project data quality depends strongly on the noise of the injection process we missed doing sufficient preliminary studies (by lack of manpower, e.g.)


V. Outlook – more results in process…Geoelectric Downhole Measurements:

ongoing measurements

signal processing and inversion

sensitivity studies concerning

measurement configurations

Combined Surface-Downhole Measurements

measurement configurations

3rd Repeat finished in end of April (for verification of CO2-migration trend)

additional profiles at the surface for lateral separation of migration progress

were measured in May and are under evaluation nowwere measured in May and are under evaluation now

signal processing is ongoing

3D inversion is planned


Thanks to all involved persons!Thanks to all involved persons!

We thank the Federal Ministry of Education and Research,

and its R&D program p g"Geotechnologien" for funding

our work.

…and for your attention!


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Geoelectric Crosshole andGeoelectric Crosshole and · PDF fileGeoelectric Crosshole andGeoelectric Crosshole and Surface-Downhole Monitoring: ... penetration range. (b) ... Resistivity