corrosion inhibitor evaluation
DESCRIPTION
corrosionTRANSCRIPT
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Evaluation of Corrosion Inhibitors
Champion Technologies
Houston, TX
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Introduction
Oilfield CorrosionParameters Affecting CorrosionCorrosion InhibitionInhibitor Evaluation -
Parameters Affecting Corrosion
PressureTemperatureDissolved GasesBrine CompositionFlow VelocityOil/Water Ratios -
Corrosion Inhibition
MechanismClassificationAnodic / Cathodic / Mixed
Organic / Inorganic
Film Forming
-
Treating Methods
WellsPeriodic Batch
Continuous
-
Treating Methods
PipelinesPeriodic 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
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Constant Concentration Wheel Test Result
CO2/CH4 : 0.8/16.7 MPa (116 / 2422 psi), 110C
10% Kerosene, 90% Brine
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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
5% Kerosene, 95% Brine
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Partition Wheel Test
Dispense Inhibitor In Fluids
Leave Undisturbed
Siphon Water
Start Test
Retrieve Coupon
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Wheel Test Advantages
Simple TestHigh TemperaturesHigh PressuresSweet/Sour TestScreening of Inhibitor PossibleLow Pressure15 psia
180F (82 C)
30 rpm
High Pressure20,000 psia
400F (204 C)
30 rpm
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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.
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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
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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
10% Kerosene, 90% Brine
20 PPM
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RCE Partitioning and Film Persistency Tests
Similar To Wheel Test ProcedureContinuous Monitoring Using LPR -
RCE Partition Test
CO2 Sparge, 72 C, 3000 RPM
10% Kerosene, 90% Brine
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RCE Film Persistency Test
CO2 Sparge, 72 C, 3000 RPM
5% Kerosene, 95% Brine
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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
10% Kerosene, 90% Brine
Inject Inhibitor
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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 ApplicationsTemperature180F (82 C)
Pressure15 psia
Velocity0-4 ft/sec (1.3 m/s @ 2000 rpm)
0-2 Pa Shear Stress
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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
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Electrochemical Corrosion Cell
Coupon 1
Coupon 2
Coupon 3
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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
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Flow Loop Advantages
High PressuresHigh TemperaturesWeight Loss, LPR & ECN CapabilitiesHigh VelocitiesSweet Or Sour TestsTemperature212F (100 C) max.
Pressure2000 psia (14 MPa)
Velocity20 ft/s (6 m/s)
300 Pa Shear Stress
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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
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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
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Advantages Of Autoclave
High PressuresHigh TemperaturesHigh Shear ValuesSweet Or Sour TestsTemperature450F (212 C) max.
Pressure5000 psia (34 MPa)
Velocity0-54 ft/sec (16.5 m/s)
0-232 Pa Shear Stress
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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 TestingWheel 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)
CORROSION RATE (mils/yr)
RN-247 400 PPM
RN-247 600 PPM
0
10
20
30
40
50
60
70
80
012345679101213151618
TIME (HR)
CORROSION RATE (mils/yr)
AN2-29
RN-246
RU-223
RN-234
RU-205
0
10
20
30
40
50
60
70
0235689
11121415
TIME (HR)
CORROSION RATE (mils/yr)
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)
CORROSION RATE (mils/yr)
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