March 9, 2016
Victrex Energy Solutions
Assessing Polymer Performance in
Hot and Sour Oil and Gas Environments
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AUDIOVISUAL
PRESENTATION
Speakers
Dr. Geoff Small
Energy Market Technology Manager
Victrex
Dr. Alexandra Torgersen
Consultant
Alexandra Torgersen Engineering
Overview Predicting Lifetime in Hot and Sour Environments
NORSOK and ISO ‘compliance’ are frequently referred to by polymer suppliers
Goal: demonstrate the current best possible assessment of lifetime in service
and outline the potential pitfalls of using inappropriate data
NORSOK M710 Standard What is it?
Standard written as test protocol – not as “pass / fail” standard
Testing specified for using Arrhenius extrapolations
No specific test temperatures or duration
Open for differences in testing and interpretation of results
Test Setup Challenges
No specific temperatures—need for acceleration
No specified test duration—50% reduction in properties
-50
-40
-30
-20
-10
0
10
20
30
40
50
0 500 1000 1500 2000 2500
125°C
135°C
145°C
-50
-40
-30
-20
-10
0
10
20
30
40
50
0 500 1000 1500 2000 2500
125°C
135°C
145°C
Interpretation Challenges
Arrhenius extrapolation—not an exact science
Are flat lines on a graph a problem or success?
-50
-40
-30
-20
-10
0
10
20
30
40
50
0 500 1000 1500 2000 2500
125°C
135°C
145°C
Interpretation Challenges
NORSOK M710 Standard
Test protocol for learning about polymers and elastomers
Need sensible input to give sensible results
Always present all results—interpret results based on specific application
Be careful about extrapolations—eventually degradation happens
Summary
Data from Standard Tests
The most common standards are : ISO 23936 Parts 1 & 2 and NORSOK M710 Edition 3
Approach: ageing at three different temperatures to predict max operating temperature for
25 year lifetime or predicting material lifetime at specific operating temperature
‘Compliance’ means testing in line with the standard
None of the test methods are entirely prescriptive leading to varying degrees of data
presented and lack of clarity around the experimental variables
Test Requirements Overview
Standard material data
RGD testing (elastomers only)
Ageing test (most commonly evaluated and discussed)
Test Methods Ageing Overview
Ageing in at least 3 temperatures in sweet or sour environment
Arrhenius-type extrapolation used to predict lifetime if possible
Assumes a single degradation process and a linear change with time
Material Lifetime Estimates ISO Standard
Test Method Observations Taking a Closer Look
Materials do not comply with the standard—the test method used may comply
Ageing tests estimate polymer lifetime at lower service temperatures
The acceptance criteria are used for lifetime estimation—they are not ‘pass’ or ‘fail’ criteria
Volume swell, weight gain or any agreed mechanical property
Most common mechanical properties are tensile strength / modulus
Lifetime then refers to the time taken to the loss of 50% of this property
Hot and Sour Performance Life Prediction: Useful Tool or Misleading Guidance?
Up next—data on VICTREX® PEEK 450G™ polymer or other Victrex polymers
Shows importance of:
Selection of the appropriate properties for measurement
Selection of the most suitable test duration
Other supporting data can be used to augment the data generated in these test protocols
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Experimental Data from
NORSOK M710 (Editions 2 and 3)
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NORSOK M710: Edition 2
Temp:175°C, 195°C & 210°C Sour Gas Content: 2% Durations, 35 days, 24 days and 25 days
Tensile Modulus: VICTREX® PEEK 450G™ Polymer
NORSOK M710: Edition 2 Observations
Strength and modulus data suggests PEEK will have near infinite lifetime
in the 2% NORSOK environment—strain data suggests a much shorter lifetime
Very little change in properties: selection of appropriate temperature and duration?
Report concluded that PEEK has "very" long lifetime up to 220°C in this environment
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NORSOK M710: Edition 3 Temp: 195°C, 210°C & 225°C Sour Gas Content: 10% Time: Up to 105 days
NORSOK M710: Edition 3 Tensile Strain: VICTREX® PEEK 450G™ Polymer
Tested at an additional temperature
Improved correlation at elevated temperatures
This should lead to a better estimate of lifetime
Temp: 195°C, 210°C, 225°C, 240°C Sour Gas Content: 10% Time: Up to 105 days
NORSOK M710: Edition 3 Estimating Lifetime: VICTREX® PEEK 450G™ Polymer
Data set with four temperatures provides better correlations
Significantly reduced lifetime prediction, especially at lower temperatures
Temperature (°C)
220
210
200
190
180
170
160
150
140
130
Three Data Sets
t50 (years)
1.1
2.5
6.1
15.3
40.3
110.4
317.2
958.0
3052.1
10299.2
Four Data Sets
t50 (years)
1.3
2.7
5.8
13.1
30.5
74.0
187.1
494.2
1368.4
3985.5
NORSOK M710: Edition 3 Estimating Lifetime: VICTREX® PEEK 450G™ Polymer
Strain at break significantly more sensitive to ageing—lower life estimate
Tensile modulus data provides unreliable and poor correlations for
thermoplastics
Temperature (°C)
220
210
200
190
180
170
160
150
140
130
Lifetime Tensile Strength t50 (years)
1.1
2.5
6.1
15.3
40.3
110.4
317.2
958.0
3052.1
10299.2
Lifetime Tensile Strain t50 (years)
0.2
0.3
0.4
0.7
1.1
1.7
2.9
4.9
8.5
15.1
Lifetime Tensile Modulus t50 (years)
1
1.0
1.5
2.3
3.7
6.0
10.0
17.1
29.9
53.9
Conditioning Pre-treatment will depend on the type of polymer
Selective use of degradation data
• Correlation of halving duration versus temperature increases from
o 0.80 to 0.93
Temperature (°C) t50 (years) (post 500
hours data) t50 (years) (all data)
240 0.2 0.3
230 0.4 0.6
220 0.7 1.3
210 1.4 2.7
200 2.8 5.8
190 5.7 13.1
180 11.8 30.5
170 25.7 74.0
160 57.6 187.1
150 134.4 494.2
140 326.7 1368.4
130 829.9 3985.5
Test Duration is Important Tensile Modulus: VICTREX® PEEK 450G™ Polymer
Using long-term data is unusual—short-term data is not useful
NORSOK and ISO seen as a ‘task’ and cost to sell to Oil & Gas market
Max duration usually 35 days at lower temperatures—12 days at highest
Short-Term Data Ending Tests Early: VICTREX® PEEK 450G™ Polymer
Early termination has resulted in a significant
over-estimate of lifetime at temperature
Temperature (°C) Lifetime(Long-term
data)
Lifetime(Short-term
data)
220 1 1
210 3 4
200 6 11
190 15 33
180 40 102
170 110 329
160 317 1127
150 958 4089
140 3052 15791
130 10299 65205
Short-Term Data VICTREX® PEEK 450G™ Polymer and Experimental Polymer
500-hour testing clearly does not give the whole picture
Chemical Analysis Molecular Weight: VICTREX® PEEK 450G™ Polymer
Tensile strength may change very little over the course of the experiment
But molecular weight is changing from the beginning of the experiment
Quantum Mechanical Model Moving Towards a Predictive Model
Bond orders and dissociation energies
Thermodynamic driving forces
Transition states
Kinetics
Product 3TS3’
TS_inter
TS 3
Inter
TS 2
Reactant
Product 2
+ H2O
Conclusions Lifetime Predictions
NORSOK M710 Edition 3 and ISO 23936 are excellent standards for assessing the
performance of polymers in aggressive oilfield environments
Must select the most appropriate property parameters for evaluation
Must ensure the most appropriate ageing duration is selected
Our Stance Victrex Leading the Way
Victrex—leading in lifetime assessment of PEEK polymers and beyond
Ask your polymer suppliers for the same level of detail
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