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Premium MMS-NR (AISI 4138M) Sucker Rods. Alejandro F. Ameglio – Head Technical Services Tenaris Rods Division. Contents. Chemical Analysis Mechanical Properties Laboratories Tests Field experiences Conclusions. Chemical Analysis.
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Premium MMS-NR (AISI 4138M)Sucker Rods Alejandro F. Ameglio – Head Technical Services Tenaris Rods Division
Contents • Chemical Analysis • Mechanical Properties • Laboratories Tests • Field experiences • Conclusions Premium MMS-NR (AISI 4138M) Sucker Rods
Chemical Analysis As it can be observed, main difference between Grades UHS-NR and MMS-NR is the Nickel (Ni) content. Premium MMS-NR (AISI 4138M) Sucker Rods
Mechanical Properties Mechanical properties are the same for all Grades Premium MMS-NR (AISI 4138M) Sucker Rods
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 Premium MMS-NR (AISI 4138M) Sucker Rods
Results of Lab tests 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. Premium MMS-NR (AISI 4138M) Sucker Rods
Field history 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: 8200-9800 ft (2500-3000 m) • Production rates: 300-600 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 Premium MMS-NR (AISI 4138M) Sucker Rods
Field evolution Field experience Premium MMS-NR (AISI 4138M) Sucker Rods
Field evolution Field experience Major problems were related with sucker rod failures Premium MMS-NR (AISI 4138M) Sucker Rods
Field data analysis 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. Premium MMS-NR (AISI 4138M) Sucker Rods
Field data analysis - Conclusions 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 40-70 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. Premium MMS-NR (AISI 4138M) Sucker Rods
Field evolution after AISI 4138 rods Field experience Premium MMS-NR (AISI 4138M) Sucker Rods
Tabla 2- Caracterización del agua de formación de los pozos en ensayo Rod body failures evolution Field Experience Premium MMS-NR (AISI 4138M) Sucker Rods
Tabla 2- Caracterización del agua de formación de los pozos en ensayo Premium MMS-NR (AISI 4138) failures evolution Field experience Premium MMS-NR (AISI 4138M) Sucker Rods
Grade of sucker rods installed Field Experience Premium MMS-NR (AISI 4138M) Sucker Rods
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 Premium MMS-NR (AISI 4138M) Sucker Rods