Intrinsic Fiber Optic Chemical Sensors for Subsurface ... · 3 Problem & Technology Project Phases Progress Evaluation at elevated pressure and temperature Study under stress conditions

1

Intrinsic Fiber Optic Chemical Sensors for Subsurface Detection of CO2

Intelligent Optical Systems, Inc.

Jesús Delgado Alonso, PhD

DOE Technical Monitor: Barbara Carney

2

Intelligent Optical Systems, Inc. (IOS)

Founded in April, 1998 Focus areas:

Physical, chemical, and biomedical optical and electronic sensors

Advanced light sources and detectors >$3.5M in equipment 11,500 sq. ft. facility in Torrance, CA Several spin-off companies with >$22M in

private funding

3

Problem & Technology

Project Phases

Progress Evaluation at elevated pressure and temperature Study under stress conditions Initial field testing of deployment system, elements, and protocols.

Planned Work

Conclusions

Intrinsic Fiber Optic Chemical Sensors for Subsurface Detection of CO2

4

Problem/Opportunity

Reliable and cost-effective monitoring is important to making gas sequestration safe.

Desirable analytical systems characteristics: Provide Reliable Information Monitor continuously Cover large areas Operate for years with little or no maintenance Cost effective

5

Technology

Distributed intrinsic fiber optic sensors for the directdetection of carbon dioxide.

Unique Characteristics Direct measurement of CO2

The entire length of an optical fiber is a sensor

Sensors are capable of monitoring CO2 in water and in gas phase.

6

TechnologyZone-by-zone monitoring using a sensor cable with multiple sensor segments

pCO2 (mmHg)

0 50 100 150 200 250

Dep

th (m

)

0

500

1000

1500

2000

Average pCO2 along the length of each sensor segment

Sensor segments

pCO2 (mmHg)

0 50 100 150 200 250

Dep

th (m

)

0

500

1000

1500

2000

Distribution segments (standard

optical fiber)

7

A silica glass core fiber is coated with a polymer cladding containing a colorimetric indicator. Upon exposure of any segment of the fiber, the CO2diffuses into the cladding and changes color.

A light source is placed at one end of the fiber and a photodetector at the other end. The light transmitted through the fiber varies with the concentration of CO2.

(Left) Fiber structure of colorimetric distributed fiber optic sensors; (right) fiber optic CO2 sensor rolled onto a spool. Microscopic detail shows uncoated fiber, and fiber coated with the sensitive cladding.

Technology

8

CO2

CO2

Technology

The optical fiber must be exposed to the aqueous matrix (or gas)

Sensor cable incorporating multiple optical fiber sensors, which are exposed to the environment.

9

Phase I Development of advanced intrinsic fiber optic sensors and readout

(length up to 2,500 ft. and able to withstand corrosive liquids).

Sensor evaluation and demonstration in simulated subsurface conditions.

Pressure Temperature

Phase II

Subsurface sensor deployment and operation (in a 5,900 ft. deep well at up to 2,000 psi).

Phase III

Project Phases

10

The transmission of light through the fiber depends on the concentration of CO2, and isreversible.

Light at wavelengths far from the absorbance of the indicator dye are unaffected by thepresence of CO2, which enables the system to be self-referenced.

Time (s)

4000 6000 8000 10000 12000 14000

Sen

sor S

igna

l (co

unts

)

6000

8000

10000

12000

14000

0.0% CO2

1.0% CO2

6.0% CO2

Reference wavelength6.0%

1.0%

0.0%

6.0%

1.0%

0.0%

Testing at Ambient Pressure

11

Testing at Simulated Subsurface ConditionsPressure

Sensor fiber spool

Optical connector

12

Gas cylinders

Pressurized vessel

Injection pumps

Control unit

Sensors immersed in water insidethe pressurized vessel

Injection pumps control gas flowand pressure

Gas cylinders with different CO2concentration (%) are used

Experiment Type 1: Constant CO2concentration and increasingpressure

Experiment Type 2: Constantpressure and varying CO2concentration


13

Time (s)

0 50 100 150 200 250

Sens

or S

igna

l (co

unts

)

0.0

2.0e+4

4.0e+4

6.0e+4

8.0e+4

1.0e+5

1.2e+5

1.4e+5

Increasing Total Pressure and pCO2

Increasing Total Pressure. Constant pCO2 (nitrogen)

P = 20 psipCO2= 0.2 psi










Test 1: Nitrogen cylinder and increasing total pressure (black)Test 2: 1% CO2 in nitrogen cylinder and increasing total pressure (blue)


14

Progress – Simulated Subsurface ConditionsPressure

Test 1: Nitrogen cylinder and increasing total pressure (black)Test 2: 6% CO2 in nitrogen cylinder and increasing total pressure (green)

Time (s)

0 50 100 150 200 250 300

Sens

or S

igna

l (co

unts

)

0.0

5.0e+4

1.0e+5

1.5e+5

2.0e+5

2.5e+5

Increasing Total Pressure. Constant pCO2 (nitrogen)Increasing Total Pressure and pCO2 (at 6% v/v)




P = 200 psipCO2= 12 psi

P = 300 psipCO2= 18 psi







15

Time (hours)

0.0 0.5 1.0 1.5 2.0 2.5

Sen

sor S

igna

l (co

unts

)

2.0e+4

4.0e+4

6.0e+4

8.0e+4

1.0e+5

1.2e+5

Pre

ssur

e (p

si)

0

500

1000

1500

2000

2500

Increasing Total Pressure. Increasing pCO2 (0.2% CO2)Increasing Total Pressure. Constant pCO2 (nitrogen)



P = 2,050 psipCO2= 4.1 psi


P = 350 psipCO2= 0.0 psi P = 2,050 psi

pCO2= 0.0 psi

Dissolved CO2 is proportional to pCO2

Test 1b: Nitrogen cylinder and increasing total pressure (black)Test 4: 0.2% CO2 in nitrogen cylinder and increasing total pressure (purple)

Testing at Simulated Subsurface ConditionsPressure (2,050 psi)

16

Time (hours)

4 5 6 7 8 9 20 21 22 23

Sen

sor S

igna

l (co

unts

)

2.0e+4

4.0e+4

6.0e+4

8.0e+4

1.0e+5

1.2e+5

Pre

ssur

e (p

si)

0

500

1000

1500

2000

2500

Dissolved CO2 is proportional to pCO214 to 8 h: Pressure set at 350 psi. Gas cylinders: N2 – 0.2% – 1% – 6% CO220 to 23 h: Pressure set at 2,050 psi. Gas cylinders: N2 – 0.2% – 1% – 6% CO2

Nitrogen

pCO2= 20 psiCO2 = 6%

pCO2= 3.5 psiCO2 = 1%

pCO2= 0.7 psiCO2 = 0.2%

pCO2= 4.1 psiCO2 = 0.2%

pCO2= 21 psiCO2 = 1%

Nitrogen


17

CO2 Partial Pressure (psi)

0 5 10 15 20 25S

igna

l Rat

io0.5

1.0

1.5

2.0

2.5

3.0

3.5

Calibration Curve Signal ratio vs. pCO2

Signal ratio vs. dissolved CO2

CO2 Partial Pressure (psi)

0 1 2 3 4 5

Sig

nal R

atio

0.5

1.0

1.5

2.0

2.5

3.0

3.5


18

Testing at Simulated Subsurface ConditionsTemperature

Time (s)

310 315 320 325 330 335

Ref

eren

ce S

igna

l (co

unts

)

30000

35000

40000

45000

50000

55000

60000

Sen

sor S

igna

l (co

unts

)

30000

35000

40000

45000

50000

Time (minutes)

350 355 360 365 370 375

Ref

eren

ce S

igna

l (co

unts

)

30000

35000

40000

45000

50000

55000

60000

Sen

sor S

igna

l (co

unts

)

20000

30000

40000

50000

Temperature 40C

Nitrogen Nitrogen Nitrogen

25% CO2 25% CO2

Temperature 60C


25% CO225% CO2

Time (s)

250 255 260 265 270

Ref

eren

ce S

igna

l (co

unts

)

30000

35000

40000

45000

50000

55000

60000

Sen

sor S

igna

l (co

unts

)

30000

32000

34000

36000

38000

40000

42000

44000

Temperature 80C


25% CO2 25% CO2

Time (s)

175 180 185 190 195 200

Ref

eren

ce S

igna

l (co

unts

)

30000

35000

40000

45000

50000

55000

60000

Sen

sor S

igna

l (co

unts

)

34000

35000

36000

37000

38000

39000

40000Temperature 100C


25% CO2 25% CO2

19

Progress – Simulated Subsurface ConditionsTemperature

Time (s)

110 115 120 125 130

Ref

eren

ce S

igna

l (co

unts

)

30000

35000

40000

45000

50000

55000

60000

Sen

sor S

igna

l (co

unts

)

34000

35000

36000

37000

38000

39000



25% CO2 25% CO2

Time (s)

135 140 145 150

Ref

eren

ce S

igna

l (co

unts

)

52000

54000

56000

58000

60000

62000

64000

Sen

sor S

igna

l (co

unts

)

66000

68000

70000

72000



25% CO2 25% CO2

Time (minutes)

10 15 20 25

Ref

eren

ce S

igna

l (co

unts

)

40000

42000

44000

46000

48000

50000

Sen

sor S

igna

l (co

unts

)

1.284e+51.286e+51.288e+51.290e+51.292e+51.294e+51.296e+51.298e+51.300e+51.302e+51.304e+5

Temperature 175C


25% CO2 25% CO2

20

Time (minutes)

0 5 10 15 20

Nor

mal

ized

Sen

sor S

igna

l

0.9

1.0

1.1

1.2

1.3

1.4

1.5

1.6

1.7Temperature = 40 CTemperature = 60 CTemperature = 80 CTemperature = 100 CTemperature = 120 CTemperature = 140 CTemperature = 175 C

Demonstrated sensor operation up to 175°C Sensor aging is significantly accelerated at temperatures >140°C As expected, sensitivity decreases with temperature because the CO2 solubility

in the sensitive polymer decreases.

Progress – Simulated Subsurface ConditionsTemperature

21

Progress – Accelerated Degradation Tests

Stress Conditions High-power lighting Corrosive matrix (low pH and high salinity) Elevated water flow rate Highly biologically-contaminated matrix Temperature cycles.

We designed Accelerated Degradation Tests (ADT) based on theHighly Accelerated Life Test (HALT) methodology. The first objective is to collect information that allows us to

improve sensor lifetime The second objective is to quantitatively estimate the lifetime

of the fiber optic sensors.

22


Sensor films covered with a protective, gas-permeable coating wereexposed to a highly biologically-contaminated matrix

The antimicrobial effect of three coating materials was measured The CO2-sensitive polymer was replaced with an oxygen-sensitive

polymer.

Oxygen sensitive film covered by protective cladding materials

Control in DI water

Highly colonized nutrient media

Samples exposed tocontinuous bacteria incubation

23

Progress – Accelerated Degradation Tests Sensor films covered with a protective, gas-permeable coating were

exposed to a highly biologically-contaminated matrix The CO2-sensitive polymer was replaced with an oxygen-sensitive

polymer Bacteria was allowed to grow on the polymer for several weeks The antimicrobial effect of three coating materials was measured by

measuring the oxygen consumption of the biological layer on thepolymer.

Time (minutes)

0 10 20 30 40 50 60

Oxy

gen

(mg/

L)

4.0

4.5

5.0

5.5

6.0

6.5

7.0

7.5

8.0DC 3140 Coating exposed to bacteriaDC3140 Coating in clean waterIOS 21-2 Coating exposed to bacteriaIOS 21-2 Coating in clean waterGE Coating exposed to bacteriaGE Coating in clean water

24


Sensor fiber segments were exposed to elevated water flow rates forseveral months

Sensitivity to CO2 was measured periodically.

Fiber optic sensor prototypesExposed to continuous water flow

Water pump

Fiber optic sensor prototypesControl samples

25


Sensor fiber segments were exposed to elevated water flow rates forseveral months

Sensitivity to CO2 was measured periodically.

Time (days)

0 25 50 75 100 125

Tran

s/Tr

ans

o (6%

Co2

)

1.0

1.2

1.4

1.6

1.8

2.0FlowNo Flow

Time (days)

0 25 50 75 100 125

Tran

s/Tr

ans0 (6

% C

O2)

1.0

1.1

1.2

1.3

1.4

1.5

FlowNo Flow

Fiber Type 1 Fiber Type 2

26


Sensor fiber segments were exposed to ambient and elevatedtemperature cycles

Sensitivity was measured before and after each temperature cycle In parallel, sensor fiber segments were maintained at elevated

temperature and sensitivity was measured periodically.

Temperature Cycle A (n cycles)Cycle B (m cycles)

Temperature 2

Temperature 1

Temperature ST Test Test Test Test

27


Sensor fiber segments were exposed to ambient and elevatedtemperature cycles.

Test Progress

Initial 70C C1 70C C2 70C C3 70C C4 70C C5 70C C6 70C C7 70C C8

Nor

mal

ized

Sen

sor S

igna

l (Se

nsiti

vity

)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

0.0% CO2

1.0% CO2

6.0% CO2

28


Sensor fiber segments were exposed to ambient and elevatedtemperature cycles.

Test Progress

Initial 70C C1 70C C2 70C C3 70C C4 70C C5 70C C6 70C C7 70C 10 70C C13 70C C16

Nor

mal

ized

Sen

sor S

igna

l (S

ensi

tivity

)

0.0

0.5

1.0

1.5

2.0

0.0% CO2

6.0% CO2

10.0% CO2

29

Progress – Accelerated Degradation Tests Sensor fiber segments were exposed to ambient and elevated

temperature cycles, and sensitivity was measured periodically (black) In parallel, sensor fiber segments were maintained at elevated

temperature and sensitivity was measured periodically (blue) Eight ADT cycles corresponded with 3 years/1,095 days of sensor

operation at constant temperature.

Thermal ADT Cycles

0 2 4 6 8

Sens

itivi

ty a

t 6%

CO

2

1.60

1.62

1.64

1.66

1.68

1.70

1.72

1.74

1.76

1.78

ADT study at 70C

Thermal ADT Cycles

0 2 4 6 8

Sens

itivi

ty a

t 6%

CO

2

1.60

1.62

1.64

1.66

1.68

1.70

1.72

1.74

1.76

1.78

Days at elevated temperature

0 10 20 30 40 50 60 70

ADT study at 70CContinuous Operation at 70C

30

Progress – Accelerated Degradation Tests Sensor fiber segments were exposed to ambient and elevated

temperature cycles, and sensitivity was measured periodically (black) In parallel, sensor fiber segments were maintained at elevated

temperature and sensitivity was measured periodically (blue) Eight ADT cycles corresponded with 3 years/1,095 days of sensor

operation at constant temperature.

Thermal ADT Cycles

0 2 4 6 8

Sens

itivi

ty a

t 6%

CO

2

1.60

1.62

1.64

1.66

1.68

1.70

1.72

1.74

1.76

1.78

Days at elevated temperature

0 200 400 600 800 1000

ADT study at 70CContinuous Operation at 70C

31


Based on the ADT studies, and assuming linear decrease in sensitivityover time, we predict ~10 years of sensor service life.

Time (days)

0 10 20 30 40 50 60 70

Sens

itivi

ty a

t 6%

(96

ppm

) CO

2

1.0

1.2

1.4

1.6

1.8

2.0

Time (months)

0 12 24 36 48 60

Sens

itivi

ty a

t 6%

(96

ppm

) CO

2

1.0

1.2

1.4

1.6

1.8

32

Sensor Cable Fabrication and Deployment

Distribution segment

Modular cable includes: External strength member Distribution segments Sensor segments Connector protector Cable head

External member

Connector protector

Cable head

Sensor segments Final loop

connector

33



Distribution segment includes eight standardoptical fibers: Four fibers connected to LEDs Four fibers connected to the photodetector.

Distribution cableLength: 1,600 m

Total Fiber: 12,800 m

Photodetector1 2 3 4

LEDs (Light Sources)


34


Stainless steel tube (wire) Serves as support for sensor cable deployment Will be used during development for CO2

release.

Stainless steel tube spool

External strength member Stainless steel

tube spool

Sensor cable spool

35


Connector protector

Sensor segment & metallic tube

Distribution segment &

metallic tube

Optical connector

Connector protector Connects the stainless steel tube and the optical

cables Mechanically protects the optical connectors.

36


Final loop connector

Loop optical connector

Connector protector Connects the stainless steel tube and the optical

cables Mechanically protects the optical connectors.

37


Sensor segments Incorporate fiber optic sensors protected

mechanically but exposed to the aqueous (gas)matrix.

Sensor segments

CO2 fiber sensors

Fiber sensors

38


Cable head Protects the cable during deployment.

Cable head

Cable head

39

Sensor deployment Release of CO2 at various depths System validation.

Proposed CO2 Sensor Well Number DOE-1

Well Test Configuration

20" 65#, H Conductor Pipe 150'@150' in 26" hole

13 3/8" 54#, K-55 Surface Casing @1500' in 17 1/2" hole 1500'Cemented to Surface

9 5/8" 53.5#, N80 Casing@5350' in 12 1/4" holeCemented to Surface

Fiber Optic CO2 Sensor Cable

1/4in Stainless TubingAdjustable Depth for CO2 Injection

Plugged Back Depth 5250'

Ongoing and Planned Work

40

Demonstrated fiber optic sensor for CO2 monitoring in gas phase and for dissolved CO2 monitoring in aqueous matrices, capable of operating at elevated temperatures and pressure.

Conducted Accelerated Degradation Tests under a variety of stress conditions, and evaluated sensor limitations and stability.

Developed instrumentation demonstrating satisfactory performance while operating sensor cables 2 km in length. Calculations predict continued good performance for sensors 3 km and longer.

Designed and fabricated sensor cables. Developed and preliminarily tested sensor deployment system and

protocols. The system is being prepared for field deployment and testing by

controlled release of CO2 in a deep well.

Conclusions

41

Acknowledgments

GeoMechanics Technologies: (downhole sensor deployment)

Michael S. Bruno and Jeff Couture

NETL Department of Energy:Barbara Carney and Robie Lewis

Intelligent Optical Systems:Narciso Guzman, Straun Phillips and Sreekar Marpu

Documents

Intrinsic Fiber Optic Chemical Sensors for Subsurface ... · 3 Problem & Technology Project Phases Progress Evaluation at elevated pressure and temperature Study under stress conditions