CO2 Flooding ConferenceMidland, Texas
December 3-7,2012Reciprocating Downhole Pumps
Joe Schoenfeld-Engineering ManagerQuinn Pumps
a Division of Lufkin Industries
OverviewOverviewDownhole Corrosion-CO2
API 11AX
API 11AX Materials
Key Environmental Parameters Influencing Corrosion of Metals
Actual Pump Materials
Other Considerations
Downhole CorrosionDefinition of corrosion
• The chemical or electrochemical reaction between a material, usually a metal, and its environment that produces a deterioration of the material and its properties
CO2
• CO2 corrosion pits are round based, deep with steep walls and sharp edges
• pitting is usually interconnected in long lines but will occasionally be singular and isolated
API 11AX
Specifications for Subsurface Rod Pumps and Fittings
• API publications exist to facilitate the broad availability of proven, sound engineering and operating practices
• API publications do not infringe on using other sound engineering practices
• API publications currently cover pump sizes from 1-1/4” to 3-3/4” whether they be insert or tubing pumps
• Pumps designed and manufactured to these standards insures that they meet the dimensional (Section 6) and material requirements (Section 9) as specified in API 11AX
• The dimensional requirements assure the interchangeability and standardization of all component parts and standard materials
Materials For API 11AX Pumps
• ASTM classification of different steels
• 10XX – Plain carbon steels• 41XX – Chrome-Moly steels• 86XX – Nickel-Chrome-Moly steel• 61XX – Chrome-Vanadium steel• 72XX – Titanium-Chrome steel
• NACE MR-01-75 and API put hardness restrictions on material that can be used in the downhole operations (material dependent)
• NACE MR-01-75 and API adopted 22-23 HRC as the maximum hardness for majority of metals to be used downhole
• ISO 15156
Materials For API 11AX Pumps
Pump Barrel Materials (Plated Barrels) Table A
ID Description Inside Surface Condition
Base Core Hardness
Base Material Min. Yield
ksiA3 Chrome on
Brass0.003 min thickness 900-1160 HV 100* Thickness per side
55-62 HRA Inhibited Admiralty Brass
60
ID Description Hardness Base Material
C1 Tungsten Carbide
Ball HRA 88-89Seat HRA 88-89.5
Tungsten with Cobalt binder
Pump Materials for Balls and Seats Table D
Key Environmental Parameters Influencing Corrosion of Metals
• CO2 content• H2S content• Oxygen and other oxidizing agents• Operating temperature and pressure• Organic acids (pH)• Metal ion and metal concentrations• Flow velocities• Solids production• Biological activity• Condensing conditions• Halide (containing the chloride ion)