Corrosion Inhibitor Evaluation

Evaluation of Corrosion Inhibitors

Champion Technologies

Houston, TX

Introduction
Oilfield CorrosionParameters Affecting CorrosionCorrosion InhibitionInhibitor Evaluation

Parameters Affecting Corrosion
PressureTemperatureDissolved GasesBrine CompositionFlow VelocityOil/Water Ratios

Corrosion Inhibition
MechanismClassification
Anodic / Cathodic / Mixed

Organic / Inorganic

Film Forming

Treating Methods
Wells
Periodic Batch

Continuous

Treating Methods
Pipelines
Periodic Batch

Continuous

Inhibitor Evaluation
Laboratory TechniquesField Trial

Laboratory Techniques
Wheel TestRotating Cylinder Electrode TestFlow Loop TestRotating Coupons Autoclave TestJet Impingement Test Apparatus

Wheel Test Procedures
Constant Concentration TestFilm Persistency TestPartition Wheel Test

146.bin

147.bin

Constant Concentration Test
Simulates Continuous InjectionEvaluation Chemical EffectivenessUsed For More Corrosive Situation

Film Persistency Test
Simulates Batch ApplicationsEvaluates Inhibitor Film PersistencyUsed For Less Corrosive Situations

Partition Test
Simulates Continuous InjectionEvaluates Partitioning CapabilitiesUsed For Wet Gas PipelinesUsed For Low Velocity Pipelines

Constant Concentration Wheel Test Procedure

Chemical Dispensed in Fluids

Coupon Inserted

Wheel Oven at Temperature

Wheel Rotation Started

Test Fluids Sparged

Test Vessels Assembled

Coupon Cleaning Procedure
Rinse With XyleneClean With Inhibited HClRinse With WaterScrub With Steel Wool PadRinse With IPADry & Weigh

Calculations
Weight Loss, W =
Blank Wt. Loss - Inhibited Wt. Loss
% Protection =
(Weight Loss * 100) / Blank Wt. Loss
Corrosion Rate (mpy) =
W = weight loss (mg)

D = Density (g/cm3)

A = Area (inch2)

T = Exposure time (hours)

534 * w

D * A * T

Constant Concentration Wheel Test Result

CO2/CH4 : 0.8/16.7 MPa (116 / 2422 psi), 110C

10% Kerosene, 90% Brine

Film Persistency Test Procedure

Film Coupon

Rinse Coupon

Start Test

Retrieve Coupon

Film Persistency Wheel Test

CO2/CH4 : 0.8/9.0 MPa (116 / 1305 psi), 160C


Partition Wheel Test

Dispense Inhibitor In Fluids

Leave Undisturbed

Siphon Water

Start Test

Retrieve Coupon

Wheel Test Advantages
Simple TestHigh TemperaturesHigh PressuresSweet/Sour TestScreening of Inhibitor PossibleLow Pressure
15 psia

180F (82 C)

30 rpm
High Pressure
20,000 psia

400F (204 C)

30 rpm

Wheel Test Disadvantages
No Velocity EffectsWeight Loss OnlyTime Dependency of Performance

Flow Hydrodynamics - Pipe Flow

Pipe Flow:

wall shear stress value for an isothermal

parallel pipe flow is given by

where

=

density of fluid (Kg/m3)

f =

friction factor

v =

fluid flow velocity (m/s)

2

2

1

v

f

r

t

=

F comes from Moody Diagrams.

RCE Measurement Techniques
Weight Loss Linear Polarization Resistance (LPR)EISECN

RCE Test Apparatus

Rotating Cylinder

Electrode

Heater

Thermocouple

Working Electrode

Reference Electrode

Auxiliary Electrode

Gas Purge

Tube

RCE Motor

RCE Test Procedures
Constant Concentration TestPartition TestFilm Persistency TestBubble Test

Bubble Test
Simulates Continuous InjectionLow Flow SituationsEvaluates Inhibitor Ability To Migrate To The Water Phase

Constant Concentration RCE Test
Set Up ApparatusFill Fluids In Desired RatioBegin Rotation & Set TemperatureMeasure Blank Corrosion RatesInject ChemicalMeasure Inhibited Corrosion Rates

Constant Concentration RCE Test

CO2 Sparge, 72 C, 5000 RPM


20 PPM

RCE Partitioning and Film Persistency Tests
Similar To Wheel Test ProcedureContinuous Monitoring Using LPR

RCE Partition Test



RCE Film Persistency Test



RCE Bubble Test Procedure
Fill Brine and Bubble CO2Immerse ElectrodesAdd Hydrocarbon LiquidMeasure Blank Corrosion RatesInject InhibitorMeasure Inhibited Corrosion Rates

RCE Bubble Test

CO2 Sparge, 72 C


Inject Inhibitor

Advantages of RCE Tests
Easy To Set UpRelatively Lower CostWeight Loss & LPR CapabilitiesVarious Situations SimulatedScreening Of Chemicals PossibleVelocity Effects Tested

Disadvantages Of RCEs
Limited Temperature RangeLimited Pressure RangeNot Suited For High Shear ApplicationsTemperature
180F (82 C)
Pressure
15 psia
Velocity
0-4 ft/sec (1.3 m/s @ 2000 rpm)

0-2 Pa Shear Stress

Flow Loop Tests
Constant ConcentrationWeight LossLPR Electrochemical Noise

Flow Loop Test Apparatus

.

.

RE

WE

CE

Electrochemical

Cell

Pump

Mass Flow

Meter

Heating

Element

Autoclave

Brine

Tank

Hydrocarbon

Tank

N

2

/CO

2

N

2

/CO

2

N

2

CO

2

Thermowell

Electrochemical Corrosion Cell

Coupon 1

Coupon 2

Coupon 3

Flow Loop Test Procedure
Sparge FluidsFill System In Desired RatioHeat To TemperatureStart Blank Corrosion TestInject ChemicalObserve Effect On Corrosion Rates

Flow Loop Test Result

5

10

15

20

CO2/N2 : 0.3/6.7 MPa (44 / 972 psi), 72 C, 7 m/s

100 ppm

JRN-259

Flow Loop Advantages
High PressuresHigh TemperaturesWeight Loss, LPR & ECN CapabilitiesHigh VelocitiesSweet Or Sour TestsTemperature
212F (100 C) max.
Pressure
2000 psia (14 MPa)
Velocity
20 ft/s (6 m/s)

300 Pa Shear Stress

Flow Loop Disadvantages
Costly EquipmentLabor IntensiveScreening Of Chemicals Undesirable

Rotating Coupon Autoclave Test
Constant ConcentrationPartition

RCA Test Apparatus

.

.

Motor

Gas In

Thermowell

Teflon End Cap

Teflon End Cap

Rotating Cylinder Coupons (4)

Drain Port

Heating

Element

Rupture

Disk

Gas Out

Magnetic Stirring

Attachment

RCA & Flow Loop Test Results

567

584

21

22

15

19

13

18

14

21

40

48

0

100

200

300

400

500

600

Corrosion Rate (mpy)

Blank

A

B

C

D

E

Corrosion Inhibitor

1 st Data Series: RCA w/ 25 ppm inhibitor

2nd Data Series: FL w/ 75 ppm inhibitor

Advantages Of Autoclave
High PressuresHigh TemperaturesHigh Shear ValuesSweet Or Sour TestsTemperature
450F (212 C) max.
Pressure
5000 psia (34 MPa)
Velocity
0-54 ft/sec (16.5 m/s)

0-232 Pa Shear Stress

Disadvantages Of Autoclave
Relatively Costly EquipmentWeight Loss Measurements OnlyScreening Of Chemicals Undesirable

Selection Of Corrosion Inhibitor
Pour PointCompatibilityFoaming TendencyEnvironmental Concerns

Conclusions
Diagnose ProblemState Of The Art Corrosion Testing
Wheel Test

RCE Test

Flow Loop Test

Autoclave Test

Jet Impingement Electrode-990 Pa

0

50

100

150

200

250

300

350

400

02356891112181921222425

TIME (HR)

CORROSION RATE (mils/yr)

R67, 10%

R67, 25%

0

10

20

30

40

50

60

70

013456891011131415

TIME (HR)


RN-247 400 PPM

RN-247 600 PPM

0

10

20

30

40

50

60

70

80

012345679101213151618

TIME (HR)


AN2-29

RN-246

RU-223

RN-234

RU-205

0

10

20

30

40

50

60

70

0235689

11121415

TIME (HR)


RN-247 400 PPM

RN-247 600 PPM

0

200

400

600

800

1000

1200

1400

Time (HR)

Corrosion Rate (mils/yr)

LPR Corrosion

Wt. Loss

0

100

200

300

400

500

0123456791012131516

TIME (HRS)


RN-234

RU-223

AN2-29

RU-205

RN-246

0

10

20

30

40

50

60

70

80

90

% Protection

RN-178RN-206

Chemical Evaluated

78

80

82

84

86

88

90

92

% Protection

R-68R-2302R-2394

Chemical Evaluated

Documents

Corrosion Inhibitor Evaluation