NACE International East Asia Pacific Rim Area Conference & Expo 2014 September 2 – 4, 2014 Nusa Dua Convention Center Nusa Dua, Bali, Indonesia

JAKARTASECTION

Experience of Qualification Test of CRA Material

UNS N08028 (alloy 28) for Down Hole Tubular in

Sour Gas Well Application

Paper No: P30

Kukuh Soerowidjojo

Sandvik Materials Technology

Tuesday, September 16,

2014

2014 NACE EAP Conference & Expo

Outline

Objective

Background - Trend of field development

environment

Text book and past experience approach

Laboratory test

Result and discussion

Conclusion

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Objective

Qualifying UNS N08028 (Alloy 28) grade for

sour service in the given well conditions by

standard SSC/SCC corrosion test ISO 7539-1,

ISO 7539-3 (“U” bend) and ISO 7539-4 (tensile)

methods.

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Background

Increasing challenges:

HPHT fields

Sour fields

Deeper water

Shale gas field

Designated well conditions

Test temperature : 150oC (302oF)

CO2 partial pressure : 41 Bar (594.65 psi)

H2S partial pressure : 5.5 Bar (79.77 psi)

Chlorides : 75,000 mg/l (as NaCl)

Bicarbonate : 0.1% (as sodium bicarbonate)

pH at temperature * : 3.75 – 4.25

Total pressure at temp. 54 Bar (783.20 psi) – including 7.5 bar (108.78 psi)

vapour pressure.

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Environment limitation for CRA’s

NACE MR175

ISO 13680 – API 5CRA

Plotted reference conditions

Test conditions for the diagram: 1000 psi CO2 5% and 15% chlorides Stressed to 100% of yield strength at test temperature

Temperature: 150oC (302oF)

CO2 partial pressure: 41 Bar (594.65 psi)

H2S partial pressure: 5.5 Bar (79.77 psi)

Chlorides: 75,000 mg/l (as NaCl)

Bicarbonate: 0.1% (as sodium bicarbonate)

pH at temperature * 3.75 – 4.25

Total pressure at temp. 54 Bar (783.20 psi) – including 7.5 bar (108.78 psi) vapour pressure.

Client’s field conditions

Sour corrosion tests - ISO 7539-1

Constant load varies from 0.8 – 1.0 x actual

yield strength

Critical observations:

•pH (before and after

test)

•Oxygen content (before

and after test)

•Load is applied on

actual yield strength at

test temperature

“U” BEND SPECIMEN ISO 7539-3 TENSILE SPECIMEN ISO 7539-4

13

Test methods

“U” BEND SPECIMEN ISO 7539-3 TENSILE SPECIMEN ISO 7539-4

14

Observation results

No cracks are observed in the test specimens, neither “U” bends nor tensile specimens

Discussion

Literature study was very helpful to direct and funneling down the

options of materials to be selected.

ISO 7539 is a good alternative to NACE TM 0177 to test the

material in sour environment.

Stress level could be increased up to 100% of yield strength to

increase the severity of the test conditions

It is very important to get oxygen level in the test solution as low as

possible.

Oxygen content in the test solution is very important to be kept as

low as possible.

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Conclusion

Laboratory test confirmed the material selected i.e. UNS

N08028 (Alloy 28) through text book and NACE MR

0175 should resistant to sulfide stress cracking / stress

corrosion cracking risk introduced by the given

environment.

UNS N08028 (Alloy 28) PSL2 was considered qualified

to be used in the project.

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JAKARTASECTION

THANK YOU

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