9th Annual Sucker Rod Pumping Workshop - alrdc.com Annual Sucker Rod Pumping Workshop Renaissance...

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



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.



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



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)



Polished rod failures …Mechanical …what we know. Most often a result of using sucker rod coupling, and should be a

Polished rod coupling.



Polished rod failures …Mechanical …what we know.

Pin Failures:

- Mechanical advantage of formed thread versus cut thread



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


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)



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



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.



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.



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



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.



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



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



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



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



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.



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.


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9th Annual Sucker Rod Pumping Workshop - alrdc.com Annual Sucker Rod Pumping Workshop Renaissance...

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