1. Premium MMS-NR (AISI 4138M) Sucker Rods
21 November November 2018
Premium MMS-NR (AISI 4138M) Sucker Rods
Alejandro F. Ameglio – Head Technical Services
Tenaris Rods Division

2. Premium MMS-NR (AISI 4138M) Sucker Rods
21 November November 2018
Contents
Chemical Analysis
Mechanical Properties
Laboratories Tests
Field experiences
Conclusions
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3. Premium MMS-NR (AISI 4138M) Sucker Rods
21 November November 2018
Chemical Analysis
Element
Grade UHS-NR (4330M)
Grade MMS-NR (4138M)
Grade Plus (1530M)
C (Carbon)
Mn (Manganese)
S (Sulfur)
0.025 Mx.
P (Phosphorus)
Si (Silicon)
Ni (Nickel)
0.30 Mx.
0.15 Mx
Cr (Cromium)
0.2 Mx
Mo (Molibdenum)
0.05 Mx
V (Vanadium)     Nb  
Cu (Copper)
0.25 Mx.
As it can be observed, main difference between Grades UHS-NR and MMS-NR is the Nickel (Ni) content.
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4. Mechanical Properties
21 November November 2018
Mechanical Properties
Grade UHS-NR (4330M)
Grade MMS-NR (4138M)
Grade Plus (1530M)
YTS (ksi)
115 Min.
UTS (ksi)
Thermal process
Normalized
Partially tempered
Mechanical properties are the same for all Grades
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5. Premium MMS-NR (AISI 4138M) Sucker Rods
21 November November 2018
Lab Tests
A set of lab tests were done to evaluate the performance of the different steels at corrosive environments
CO2 (“sweet” corrosion)
SSC (Sulfide Stress Cracking) Resistance
Localized attack in H2S environments
Two steels were tested: AISI 4330M and AISI 4138M
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6. Premium MMS-NR (AISI 4138M) Sucker Rods
Results of Lab tests
21 November November 2018
Lab Tests
At CO2 environments both steels showed approximately the same performance.
Besides that, AISI 4138M showed a lower corrosion potential compared with the AISI 4330M.
Analyzing the behavior of them at H2S environments, both showed a poor performance.
None of them are recommended for sour service.
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7. Premium MMS-NR (AISI 4138M) Sucker Rods
Field history
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Field experience
A major company operates a field at Neuquen Basin (Río Negro Norte Field)
Going trough a natural declination process, wells were changing the ALIFT systems from ESP to Rod Pumping.
Main characteristics of the field are:
Depths: ft ( m)
Production rates: bfpd (50-90 m3/d)
Water cuts: 10-40%
Vertical wells
Load levels make Grade D rods not applicable at the first stage of field development
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21 November 2018

8. Premium MMS-NR (AISI 4138M) Sucker Rods
Field evolution
21 November November 2018
Field experience
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9. Premium MMS-NR (AISI 4138M) Sucker Rods
Field evolution
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Field experience
Major problems were related with sucker rod failures
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10. Premium MMS-NR (AISI 4138M) Sucker Rods
Field data analysis
21 November November 2018
Field experience
As the failures rates were constantly increasing, it was decided to do a complete analysis of the field data
A task force that included production engineers and specialized technicians studied data including:
Fluid analysis
Annulus gas determinations (H2S and CO2)
Bacterial measurements (SRB-Sulfate Reducers Bacteria)
Failure analysis (all of the rod failures were analyzed)
Operating conditions (spm, loads, etc)
Handling & care practices, make-up procedures, etc.
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11. Premium MMS-NR (AISI 4138M) Sucker Rods
Field data analysis - Conclusions
21 November November 2018
Field experience
Annulus gas determinations showed a low content of CO2 (partial pressure < 3psi). From this point of view, there is no a corrosion problem
However, CO2 in fluid analysis were detected (concentrations between mg/lt)
No H2S were detected, neither SRB (Bacteria).
Failure analysis indicated a corrosion-fatigue process as the responsible for the rod breaks.
NACE MR0175 (carbon steels or low alloy steels should not contain more than 1% of Ni)
As a final conclusion, a change in the steels of HS sucker rods were decided (from AISI 4330 to AISI 4138)
Those wells whit loads level less than 130% (SF=0.8) (Grade D) will be installed with Grade D rods
A task force that included production engineers and specialized technicians studied data including:
Fluid analysis
Annulus gas determinations (H2S and CO2)
Bacterial measurements (SRB-Sulfate Reducers Bacteria)
Failure analysis (all of the rod failures were analyzed)
Operating conditions (spm, loads, etc)
Handling & care practices, make-up procedures, etc.
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12. Premium MMS-NR (AISI 4138M) Sucker Rods
Field evolution after AISI 4138 rods
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Field experience
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13. Premium MMS-NR (AISI 4138M) Sucker Rods
Tabla 2- Caracterización del agua de formación de los pozos en ensayo
Rod body failures evolution
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Field Experience
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14. Premium MMS-NR (AISI 4138M) Sucker Rods
Tabla 2- Caracterización del agua de formación de los pozos en ensayo
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Field experience
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15. Premium MMS-NR (AISI 4138M) Sucker Rods
Grade of sucker rods installed
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Field Experience
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16. Premium MMS-NR (AISI 4138M) Sucker Rods
21 November November 2018
Conclusions
This material has shown to have a better performance at corrosive environment than the other type of high strength sucker rods previously tested.
A reduction in the pulling interventions rate (increase in service life) has been observed.
Even with a “sweet” corrosive environment (CO2), and because of its reduced content of Nickel (Ni), the material is less susceptible to corrosion-fatigue processes that were affecting the other type of sucker rods.
Recommendations
As with all of the high strength rods in a corrosive environments, an effective corrosion inhibition program must be applied.
Besides that, with loads level less than 140% (SF=0.8) Grade D rods are also an alternative that should be considered
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