logging techniques for co saturation & well integrity ... monitoring techniques.pdf ·...

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Logging Techniques for CO2Saturation & Well Integrity Evaluation

Laurent JAMMESIEA-GHG Monitoring Network MelbourneNovember 1st, 2006

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Schlumberger Carbon Services

Performance & Risk Management for CO2 Storage

Performance & Risk Assessment• Capacity• Injectivity• Containment

• Cost• Environment• Heath & Security• Image

Functions / Stakes

Risk Treatment

Actions

ModelingMeasurement forCharacterization

Construction Technologies& Interventions

Monitoring Measurements

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Monitoring Objectives

Performance Control– Injection efficiency – CO2 in place – displacement & trapping– Sealing

Risk Control– Containment losses– Contamination (shallower aquifers…)– Releases on surface - accumulation

Dynamic modeling calibration for reliable long-term prediction of CO2 fate

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Well Monitoring Techniques

CO2 Saturation Measurements– Nuclear– Electrical – Sonic– Sampling

Well Integrity Evaluation– Calipers (corrosion)– Electromagnetic (corrosion)– Sonic (cement)– Ultrasonic (corrosion & cement)

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Density Gamma – Gamma( )xexpNoN µρ−⋅= N: counting rate for a detector at a distance x from the source

x: source-detector spacingρ: density

maDfDb ρρρ ⋅Φ−+⋅Φ= )1(ΦD: density porosity

−−

Φ=

2

2

11

COff

bbCOS ρρ

ρρ

Baseline: Measurement:

bρ1bρ

Measurement sensitivity depends on Porosity and formation fluid / CO2 Density contrast

Time-Lapse Density Measurement

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Neutron porosity Neutron – Neutron

AmBe SOURCEAmBe SOURCE(4.35 MeV)

NucleusNucleus

ELASTIC NEUTRON SCATTERING The scattering of neutrons by Hydrogen is very efficient in reducing the neutron energy

The Hydrogen Index HI, or quantity of Hydrogen atoms in the pore space, is inferred from detector count rate ratio

Nφ

Coun

t Rat

e (c

ps)

fresh-water-filledporosity sample

Coun

t Rat

e (c

ps)

Coun

t Rat

e (c

ps)


N %φNφ

Coun

t Rat

e (c

ps)

NφNφ

Coun

t Rat

e (c

ps)


Coun

t Rat

e (c

ps)

Coun

t Rat

e (c

ps)


N %φSelectivity to CO2/H2O (brine)Potential Selectivity to CO2/CH4 (ΦN is due to H)

N

NCOS Φ

Φ−= 11

2


Time-Lapse Neutron Porosity Measurement

NΦ1NΦ

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Neutron Capture Cross-Section Neutron – Gamma

******

RST

NEUTRON ABSORPTION (OR NEUTRON CAPTURE)

Borehole sigma Formation sigmaBorehole sigma Formation sigma

SIGMA: is a measure of how fast the thermal neutrons are captured, which is a process mainly dominated by chlorine.1 11/16”

2 1/2” [chlorine] α [brine]

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Neutron Capture Cross-Section

CO2 and Water Σ values– CO2 (0.3 c.u.)– Water (55 c.u.) (@ 93,000 ppm)

X-plot Porosity – Σ – For different Water (CO2) Saturations

Selectivity to CO2/brine (H2O)

(*) Sakurai et al. , SPWLA 46th – June 26-29th - 2005

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CO2 Monitoring Using RST – Frio Experiment

Injection started on Oct 4th 2004, stopped on Oct 141,600 t/CO2 injected

Target: Frio formation (~5000 ft deep)SandstoneHigh Salinity: 93,000 ppmHigh Porosity: 32-35 p.u.High Permeability: 2.5 Darcy (air)Injector-Monitoring well spacing: 100ft

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Monitoring Using RST in Frio – Σ MeasurementCO2 Injection : Start – Oct 4th / Stop - Oct 14th

Time-Lapse CO2 Saturations Time-Lapse Σ Measurements (*) Sakurai et al. , SPWLA 46th – June 26-29th - 2005

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Neutron Inelastic Scattering Neutron - Gamma

Nucleus

Nucleus

Inelastic Gamma Rays

Nucleus

Nucleus

Inelastic Gamma Rays

INELASTIC NEUTRON SCATTERING

******2 1/2”

RST

Inelastic Spectra in CO2 and WaterTwo different C/O ratio

– Elemental Yields (accurate but low statistics)– Windows Ratio (less accurate, more precise)

Carbon to Oxygen ratio

Selectivity to CO2/CH4Selectivity to CO2/brine (H2O)Measures CO2 rich-phase and dissolved CO2

1 11/16”

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Resistivity

Casing acts like a large electrode.Current returns to surface similarly to a Laterolog tool.Rt = K * ∆V / ∆IFirst step: ∆I = (V1-V2)/RcSecond step: I’ = (V1-V2)/Rc

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1

12

−=

t

tCO R

RS

Time-Lapse Resistivity Measurement

tR1tR


Measurement & Interpretation Issues:Sensitivity to cement resistivityEffect of dissolved CO2 on brine resistivity: CO2 RwEffect of Water in Supercritical CO2

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X-Well EM Surveys

Injector 井 (open hole)

Producer井

Producer 井

92m305m

N

1 10010Resistivity (Ωm)

Saturation DistributionMonitoring of Injection front & CO2 Plume

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Sonic

BULK MODULUS P-WAVE VELOCITY (VC) DENSITY

∆VP ~ 10 %

Batzle-Wang equations with modified parameters were used for calculations. T = 57oC, P = 6750 psi, [NaCl] = 300 000 ppm(brine)

Selectivity to CO2/brine

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Downhole Fluid Analyser – CO2 Concentration

Spectrometer(Gas Analyzer)

Sample Flow

Fluorescence Detector

Lamp

Flowline

Single probemodule

Pumpout module

Multisample module(s)(Six 450cc samples)

OFA/CFA

Packer module H2O and CO2 peaks overlap in the Near-IR region

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Well Monitoring Techniques

CO2 Saturation Measurements– Nuclear techniques– Electrical – Sonic– Sampling

Well Integrity Evaluation– Calipers (corrosion)– Electromagnetic (corrosion)– Sonic (cement)– Ultrasonic (corrosion & cement)

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Well Integrity – Caliper Measurements (Corrosion)

Multifinger CaliperCasing/tubing inside diameter24 to 60 fingers

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Cement Slurry Displacement Problems

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Sonic Cement Bound Evaluation

Ampl

itude

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UltraSonic Pulse Echo Imager

The resonance technique

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Measurements

CementCementCasingCasingMudMudTransducerTransducer

FormationFormationCementCementCasingCasingMudMudTransducerTransducer

FormationFormation

Echo amplitude

(Internal casing condition)Transit time

Internal radius

Thickness

Cement Impedance

- Internal Casing Condition

- Internal Radius

- Casing Thickness

- Cement Impedance

Tool CharacteristicsCasing OD 4.5 - 13.375 in. Sampling:Casing thickness 0.17 - 0.59 in. (4.5-15 mm) -Azimuthal 5-10 deg.Acoustic Impedance 0-10 Mrayl -Vertical 0.6”- 6”Max. deviation No limit Maximum mud weightLogging speed 400 to 3200 ft/hr - WBM 16 lbm/gal

- OBM 11.6 lbm/gal*(*) Depends on composition, temperature and pressure. Good logs can be obtained in up to 1560 kg/m3 (13 lb/gal) and sometimes up to 1917 kg/m3 (16 lb/gal)

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Cement Evaluation Challenges

Discriminate– Cement– Liquid– Gas

Gas

Cement

Liquid

Acoustic Impedance 8

6

4

2

0

Light

Contaminated

Increasing Contaminatio

nNeat

Cement

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Cement Evaluation Challenges

Gas

Cement

Liquid

Acoustic Impedance 8

6

4

2

0

Light

Contaminated

Cement

Increasing Contaminatio

nNeat

USIT

LiteCrete bond quality unclear

CementWaterGas

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Imaging Behind Casing - principle

Combine USI (ultra sonic imager) measurement:– Excitation of thickness mode of the casing– Single transducer (Tx/Rx)configuration measuring resonance

and decay of thickness mode– Inversion for the acoustic impedance immediately behind the

casing

with FWI (flexural wave imager) measurement:– Excitation of flexural mode of the casing– Pitch-catch configuration (one Tx, two Rx) measuring flexural

attenuation– Due to leakage, image may reveal up to third interface

(formation/double string)

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Imaging Behind Casing Flexural Mode

R2

R1Cement

x∆

cmdBFarAmplitudeearAmplitudeNLog

cmx/*

)(20

10

∆

=α

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Imaging Behind Casing

CementWaterGas

Class G Tail cement

LiteCrete

DebondedLiteCrete

WaterAir

FWIFlexural Impedanc

Light

Neate

USITAcoustic Impedance

Liquid Contaminated

Cement

Cement

Gas

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Example:

Channeled section in LiteCRETE cement

Not identified by USIT and CBL!

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Isolation Scanner: Third Interface Echo

• Strong TIE from Flexural Wave

• ∆T independent of T-R Spacing

• ∆T = F(Annulus thickness, Wave Velocity)

Known Velocity Cement Thickness

TIE not always possible:

- Casing Eccentering

- Attenuation of annulus material

- Not enough acoustic contrast

- Large Hole/ Washouts

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Conclusion

Wells provide access to the reservoir!

Well measurements complement geophysical monitoring techniques by providing accurate local evaluation of properties

Validation and demonstration of measurement techniques is still needed, which requires tool response characterization in CO2 environment

Availability of wells also allows– Installing permanent sensors (P,T, microseismicity…)– Sampling– Performing X-Well or Well-to-surface surveys

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Questions for Designing a Monitoring System

What do I want to monitor? CO2 displacement, leak…What property change can I monitor? P, CO2 Saturation, ResistivityWhat variation am I considering?

What measurement technique can be used? Seismic, EM, Nuclear…What should be my sensor specifications? Accuracy / Precision

Where should I place my sensor? Surface, Obs. Well (Permanent, Logging…)For how long? Operation phase, surveillanceHow can I deploy it?How can I interrogate it?

How can I interpret the measurement?

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Questions?

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