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9th Annual Sucker Rod Pumping
Workshop
Renaissance Hotel
Oklahoma City, Oklahoma
September 17 - 20, 2013
Operational risk management advantages from
premium Corrosion Resistant High Strength
polished rods.
Dean Murney
NOV Wilson Canada
Sept. 17 - 20, 2013 2013 Sucker Rod Pumping Workshop 2
• Failures – Everyone wants to reduce them, but they must be identified and then an
economic solution must be found. One failure type, which can sometimes be
overlooked is polished rod failures. Most polished rod failures are fatigue failures that
occur just under the clamp. Most of these are a result of improper placement of
polished rod clamps, over torqued clamps or misaligned clamps/carrier bars. A paper
presented at the 41st annual Southwestern Petroleum Short Course in 1994 concluded
that bending stresses amplified by stress concentrations from polished rod clamps are
the most significant contributors to polished rod failures.
•
• In Canada, NOV Wilson has been running a special metallurgy polished rod which has
proven to reduce fatigue failures due to clamp placement and over torque. This unique
high strength – corrosion resistant polished rod has greater elasticity which handles
excessive clamping and/or misalignment through the carrier bar. It is also
homogenous throughout so any damage from scoring does not make it susceptible to
corrosion attack inside the score.
•
• With over 40,000 polished rods installed in Canada, case histories will be presented
which will prove the success in reducing failures with this design.
Operational risk management advantages from premium Corrosion Resistant High Strength polished rods
Sept. 17 - 20, 2013 2013 Sucker Rod Pumping Workshop 3
Operational risk management advantages from premium Corrosion Resistant High Strength polished rods
Polished Rod Failures…..do we seek complete prevention vs
or do we better manage the risks.
Polished rod failures …what we know: • Are a recognized expense in the rod pumping business ……the rod
itself, lost production, the well intervention (worse case a pump pull),
environmental
• Failures identified as
1) sealing face failure from wear or corrosion attack
2) Defined mechanical failure of the rod itself.
Sept. 17 - 20, 2013 2013 Sucker Rod Pumping Workshop 4
Operational risk management advantages from premium Corrosion Resistant High Strength polished rods
Polished rod failures …Sealing Face : loss of effective
seal area or surface finish - Vertical / horizontal scoring from solids imbedded in the packing or
solids impingement against the rod body creating a crevice.
Solutions: - Provide a hard surface finish on the polished rod, suitable for well
fluids and conditions (Chrome plate, metal spray, hard-kote/treated,
etc) while ensuring mechanical integrity of the rod is not
compromised.
- Avoid packing's with Kevlar strands that could press against the rod
surface
Sept. 17 - 20, 2013 2013 Sucker Rod Pumping Workshop 5
Operational risk management advantages from premium Corrosion Resistant High Strength polished rods
Polished rod failures …Sealing Face : loss of effective seal area or
surface finish - Eventual wear of the OD from frictional forces applied from the
packing, the wear resulting in a dimension whereby existing packing
can no longer effectively seal. (…lack of lubrication due to : high water
cut? Pumping dry? No grease zerks in stuffing box? No grease
guns??)
Solutions:
- Provide a hard surface finish on the polished rod, suitable for well
fluids and conditions (Chrome plate, metal spray, hard-kote/treated,
etc) while ensuring mechanical integrity of the rod is not
compromised.
- Polished rod lubricators/oilers, auto-lubers, enhanced routine
maintenance schedule (grease the packing)
Sept. 17 - 20, 2013 2013 Sucker Rod Pumping Workshop 6
Operational risk management advantages from premium Corrosion Resistant High Strength polished rods
Polished rod failures …Mechanical …what we know. Most often a result of using sucker rod coupling, and should be a
Polished rod coupling.
Sept. 17 - 20, 2013 2013 Sucker Rod Pumping Workshop 7
Operational risk management advantages from premium Corrosion Resistant High Strength polished rods
Polished rod failures …Mechanical …what we know.
Pin Failures:
- Mechanical advantage of formed thread versus cut thread
Sept. 17 - 20, 2013 2013 Sucker Rod Pumping Workshop 8
Operational risk management advantages from premium Corrosion Resistant High Strength polished rods
Polished rod failures …Mechanical …what we know.
Fatigue failure: - Insufficient mechanical strength for the load applied
- Corrosion induced stress crack leading to fatigue failure
- Bend induced stress crack fatigue failure
- Mechanically induced stress crack (excessive clamping force
with indentation style clamps)
- Polished rod in use may be susceptible to these failures due to
existing mechanical / metallurgical properties of rod
Sept. 17 - 20, 2013 2013 Sucker Rod Pumping Workshop 9
Operational risk management advantages from premium Corrosion Resistant High Strength polished rods Fatigue failures….solutions.
- Insufficient mechanical strength for the load applied
Know what you are putting into the well and the load being
handled….diameter, mechanical strength
- Corrosion induced stress crack leading to fatigue failure
Ensure to utilize a Corrosion Resistant rod of suitable strength for
the application
- Bend induced stress crack fatigue failure
Address issues of alignment
Is rod soft enough to allow some misalignment or
deformation(elongation)
Sept. 17 - 20, 2013 2013 Sucker Rod Pumping Workshop 10
Operational risk management advantages from premium Corrosion Resistant High Strength polished rods
Fatigue failures….solutions.
- Mechanically induced stress crack (excessive clamping force
with indentation style clamps)
Is rod soft enough to allow some deformation(elongation) before
cracking
- Polished rod in use may be susceptible to these failures due to
existing mechanical / metallurgical properties of rod
Find a rod that has mechanical and metallurgical properties that
incorporates all the solutions
Sept. 17 - 20, 2013 2013 Sucker Rod Pumping Workshop 11
Operational risk management advantages from premium Corrosion Resistant High Strength polished rods
Polished rod failure management…..consideration for a premium rod? Utilize the Pitting Resistance Equivalent test as measure for corrosion
resistance vs Metallurgy
PRE = % chromium + 3.3(% molybdenum) + 16(nitrogen)
….in order to rank stainless steels and nickel based alloys according
to their resistance to pitting corrosion the relative FeCl3 test is used.
In this test, sheet specimens are exposed to 10% FeCl3 solution for
24 hours. The temperature is Increased in 2.5 degC increments until
pitting occurs.
That gives the critical pitting temperature (CPT) or critical crevice
temperature (CCT)
Knowing your polished rod metallurgy will provide an idea of corrosion
Resistance using this baseline while also having good mechanical
properties.
Sept. 17 - 20, 2013 2013 Sucker Rod Pumping Workshop 12
Operational risk management advantages from premium Corrosion Resistant High Strength polished rods
120
110
100
90
80
70
60
50
40
30
20
10
0
°C
25 30 35 40 45 50 55 60 65 70 75
*alloy 317 LN(1.4439)
alloy 904 L(1.4539)
*Cronifer 1925 hMo(1.4529)
*Nicrofer 3127hMo(1.4562)
Nicrofer 6020 hMo(2.4856)
Nicrofer 5716 hMoW(2.4819)
Nicrofer 5923 hMo(2.4605)
alloy 316(1.4435)
*alloy S 34565(1.4565)
- Stainless steels tested in 10% FeCl3 x 6 H2O solution
- Ni-base alloys tested in 7 % H2SO4, 3 % HCl, 1 % CuCl2, 1 % FeCl3
CPT CCT
Critical Pitting Temperature CPT
Critical Crevice Corrosion Temperature CCT
PRE = % Cr + 3.3 x % Mo PREN = % Cr + 3.3 x % Mo + 30 x % N
Comparison of Critical Pitting Temperature (CPT)and Critical Crevice Corrosion Temperature (CCT)
Pitting Resistance Equivalent
Tem
pera
ture
VDM 1925 hMo is a austenitic stainless steel product found to be suitable
as a polished rod with the highest PRE index compared to other
products on the market.
Sept. 17 - 20, 2013 2013 Sucker Rod Pumping Workshop 13
Operational risk management advantages from premium Corrosion Resistant High Strength polished rods
Polished rod failure management…..consideration for a premium rod? Comparison of corrosion resistance in rod metallurgy
Thus the pitting resistance of Nitronic 5O equals that of 2205 Duplex.
= VDM
Sept. 17 - 20, 2013 2013 Sucker Rod Pumping Workshop 14
Operational risk management advantages from premium Corrosion Resistant High Strength polished rods
Consideration for a premium rod?...The VDM 1925hMo
polished rod is a product with properties to effectively
manage the operational risks noted previous.
Proven Corrosion resistance at what mechanical property…..
Homogenous metallurgy through cold drawn process….
• provide high hardness and wear resistance on the surface and a
ductile core.
Minimum 25% elongation (typical range 27-30%)
• Material does not react “brittle” during mechanical overload
• Transforms overload into deformation rather than crack.
Bar strength 87ksi Yield x 116ksi Tensile
• Zero mechanical fatigue failures registered.
Sept. 17 - 20, 2013 2013 Sucker Rod Pumping Workshop 15
Operational risk management advantages from premium Corrosion Resistant High Strength polished rods
Consideration for a premium rod? Proven Corrosion resistance at what mechanical property…..
Smooth surface finish
• 15 Rms max, typically 10Rms
Rolled thread
• Known mechanical property benefits
Reasonably “hard” surface finish
• Cold drawn process targets range 27-35 HRC on surface
• Not one case of SSC
Sept. 17 - 20, 2013 2013 Sucker Rod Pumping Workshop 16
Operational risk management advantages from premium Corrosion Resistant High Strength polished rods
Timeline for testing this premium rod….
1983: Six (6) Cronifer 1925hMo rods along with 12 duplex 2205 test
rods were installed at Redwater.
1985: The duplex 2205 rods started to pit. No such effects were seen
on the Cronifer 1925hMo rods.
1985: Esso decided to install Cronifer 1925hMo rods throughout the
entire Redwater field of more than 200 wells.
1986: Other Esso fields and producers commenced testing and
installing Cronifer 1925hMo rods with identical results
Sept. 17 - 20, 2013 2013 Sucker Rod Pumping Workshop 17
Operational risk management advantages from premium Corrosion Resistant High Strength polished rods
Sept. 17 - 20, 2013 2013 Sucker Rod Pumping Workshop 18
Operational risk management advantages from premium Corrosion Resistant High Strength polished rods
Typical well conditions of these first tests……
Number of wells . . . . . . . . . . 420
BP . . 165
ESP . . 165
Misc . . 90
Well Depth . . . . . . . . . . . . 3,000’
Water/Oil Ratio . . . . . . . . . . . 45:1
Temperature . . . . . . . . . . 95F/35C
Salinity . .110,000 PPM Chlorides
H2S . . . . . . . . . . . . . . . . . . . . . .3%
CO2 . . . . . . . . . . . . . . . . . . . . .10% Courtesy VDM Krupp Canada
Sept. 17 - 20, 2013 2013 Sucker Rod Pumping Workshop 19
Operational risk management advantages from premium Corrosion Resistant High Strength polished rods
Results from using a premium rod? Producer benefits:
- Increased polished rod run life due to
* Near elimination of broken rods at the clamp (elongation benefits )
* Reduced incidents of packing leaks due to corrosion, excessive
frictional wear
* Adequate surface hardness for application for high water cut wells
* Elimination of failed polished rods deemed corroded from
wellbore fluids
- Reduced Opex through elimination of pump pulls due to polished rod changes
Sept. 17 - 20, 2013 2013 Sucker Rod Pumping Workshop 20
Operational risk management advantages from premium Corrosion Resistant High Strength polished rods
Results from using a premium rod?
In Canada, more than 40,000 rods in service since 1985, into every rod
pumping region in Canada…..not 1 case of mechanical failure related to
corrosion from wellbore fluids.
Producers in the Williston Basin (ND/Mt) started to run these rods
approx. 6-8 years ago.
Producers report noticeably fewer incidents of mechanical failures at the
rod clamps, compared to other HS rods and elimination of rod
replacements due to corrosion attack on the sealing surface.
Sept. 17 - 20, 2013 2013 Sucker Rod Pumping Workshop 21
Operational risk management advantages from premium Corrosion Resistant High Strength polished rods
Are polished rod failures “manageable”?
Yes…..to a degree.
Does it come at a price?
Compared to not doing anything different? Perhaps not.
Compared to what rod might be used today? Yes. But offset by
the operational benefits.
Sept. 17 - 20, 2013 2013 Sucker Rod Pumping Workshop 22
Copyright
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– Display the presentation at the Workshop.
– Place it on the www.alrdc.com web site, with access to the site to be as directed by the Workshop Steering Committee.
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Other use of this presentation is prohibited without the expressed written permission of the author(s). The owner company(ies) and/or author(s) may publish this material in other journals or magazines if they refer to the Sucker Rod Pumping Workshop where it was first presented.
Sept. 17 - 20, 2013 2013 Sucker Rod Pumping Workshop 23
Disclaimer
The following disclaimer shall be included as the last page of a Technical Presentation or Continuing Education Course. A similar disclaimer is included on the front page of the Sucker Rod Pumping Web Site.
The Artificial Lift Research and Development Council and its officers and trustees, and the Sucker Rod Pumping Workshop Steering Committee members, and their supporting organizations and companies (here-in-after referred to as the Sponsoring Organizations), and the author(s) of this Technical Presentation or Continuing Education Training Course and their company(ies), provide this presentation and/or training material at the Sucker Rod Pumping Workshop "as is" without any warranty of any kind, express or implied, as to the accuracy of the information or the products or services referred to by any presenter (in so far as such warranties may be excluded under any relevant law) and these members and their companies will not be liable for unlawful actions and any losses or damage that may result from use of any presentation as a consequence of any inaccuracies in, or any omission from, the information which therein may be contained.
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