6th Annual Sucker Rod Pumping Workshop

Wyndham Hotel, Dallas, TexasSeptember 14 – 17, 2010

Development, Testing and Field Results of New Sucker Rod GradeErik Tietz, P.EArun Sriraman

Why did UPCO perform this project?

• Some of the questions which were raised from customer feedback and led us into this project are as follows:

– What are some of the factors to consider before choosing a particular grade of sucker rod?

– Why are KD rods overloaded in some environments?

– Why HS (High Strength) rods cannot be used in corrosive environment?

– When both KD and HS rods fail, is fiberglass the only option?

Summary

Sucker rod characteristics (Toughness studies and their results).

In-house Development of new grade of sucker rod. Chemistry Development Heat Treatment (Normalize and Temper)

Validation (Tests) & Field studies

Key Sucker Rod Concepts

• Key Sucker Rod Characteristics- Stress and strain related to sucker rods

- Yield and Tensile strengths of sucker rods

- Concept of Toughness for different grades of sucker rods

- Toughness as a parameter in choosing the sucker rod grade for a particular application

Stress and Strain

• Two Key characteristics from the Graph:- Load carrying capability (Vertical axis)- Amount of stretching ability (Elongation) of sucker rod.

- The load carrying capability and Elongation are two key parameters which needs to be used in combination (Toughness) in selecting a sucker rod.

- Using load carrying capability alone as a factor will lead to wrong choice of sucker rod grades.

Stress and Strain

Stress Strain Curves for Sucker Rod Grades

• Grade C, K- Low Strength and high toughness

• Grade CD, AD, KD- Medium strength and medium to high toughness.

• Grade HS- High Strength and Low toughness

Novel illustration

• A graph which shows the relationship between load carrying capability and elongation is called a toughness curve.

• The vertical height of the bars indicates the relative load carrying capability.

• The horizontal width represents the capability of the sucker rod to elongate.

Brief History

• A good understanding of sucker rod characteristics will reduce / eliminate the majority of the application failures.

Analysis of Toughness Curve

• Practical Consequences– No sucker rod with high strength and toughness.– Overloading KD rods and using HS rods in harsh

environments.– A grade in between KD and HS having good load

carrying capabilities and toughness.

– In-house Development:Developed, tensile, heat treating methods and chemistry to fill the gap between KD and HS.

Results from Toughness Studies

Process Development (Heat Treat)

• Heat treatment of any specific grade of sucker rod is a very critical process.

• Proper heat treatment at appropriate temperature and soak time is key in achieving the desired physical and toughness properties.

• Two stage process of heat treatment applicable to sucker rods:

– Normalize (Stress relieve)

– Temper (Achieve desired physical properties and improve

toughness)

Chemical Composition

Element CharacteristicsCarbon Increases the tensile strength of the material or in

other words, it provides strength.

Manganese Added in tandem with carbon to increase the tensile strength and improves wear resistance.

Nickel Makes the rod tougher. Increases the hardness and corrosion resistance.

Chrome Increases corrosion resistance, hardenability and strength.

Moly Increases hardenability, fatigue resistance and creep.

Vanadium Increases strength and toughness. Grain enhancer.

Validation - Charpy test Results

Rod Actual Tensile Actual Yield Charpy (FT-LBS)

KD 115 KSI 91 KSI 100, 102, 94 (98.6 AVG)

SD 138 KSI 107 KSI 63, 65, 53 (60.3 AVG)

HS 145 KSI 122 KSI 16, 16, 15 (15.6 AVG)

Sept. 14 - 17, 2010 2010 Sucker Rod Pumping Workshop 15

Field Tests and Results

End User: Resaca Operating Company, University BTest Well 1 Characteristics: Slightly sour environment with a pump depth of

11172’.

33 TBPD, 5 BPDO, 28 BPDW, 39% run time.

1 ¼” pump, 8 strokes/min, 144” stroke length.

• Rod Breakdown:

Rod Quantity1 ½” X 22’ polished Rod 11 ¾” X 14’ Linear8’,4’,4’,2’ – 1” HS pony rods 181” SD rods w / full hole couplings 1157/8” SD rods w / full hole couplings 1223/4” SD rods w / full hole couplings 1681” SD rods w / slim hole couplings 402” X 1 ¼” X 24’ Pump 1

Field Tests and Results

Test Well 1 Characteristics:• The rod loads were evaluated based on the modified

Goodman diagram with a service factor of 0.9 for mild corrosion.

• Rod body design loading was done based on T/4 modified Goodman diagram with a tensile of 135000 PSI.

1.0” steel – 86%0.875” steel – 92%0.75” steel – 100%1.0” steel – 36%

Field Tests and Results

• Well ran 1.25” fiberglass rods. (MTBF for rod failures was 237 days).

• String was changed to Steel rods (SD) with HS subs (High Strength Ponnies).

• After 373 days, the 2’ HS pony rod failed due to H2S corrosion fatigue.

• From Jan 15, 2009 to now (600 days), No rod problems.

Field Tests and Results

Field Tests – Well 2

• End User: Cambrian Management, Othella # 2A

• 8282’ depth, slightly sour environment.

• 40.5 TBPD, 8.5 BPDO, 32 BPDW

• 1 ¼” Pump, 9.5 SPM, C 320 – 250 – 84

• KD rods could not handle the load and high strength were not an option due to corrosion

• 2625’ 7/8 X 25 SD• 2000’ 7/8 X 25 AD• 3500’ 3/4 X 25 AD• 100’ 1 ½” X 25 Grade 1 Sinker Bars

Average failure rate for this well is 0.3. So, expectations are pulling the well due to rod failure every 3 years.

Field Tests – Well 2

• 10/17/2008, Replaced a HS sub with SD rods. HS failed due to sulphide reducing bacteria (SRB), large thumb shaped pit

• No SD rod failure for 2 1/2 years

• The average failure rate is every three years

Field Tests – Well 2

Field Test – Well #3

• Well depth 8600 feet and has 8% H2S and 7% CO2.

• 1 - 1 ½ X 26 Polished rod136 - 7/8” SD Rods207 - 3/4” SD Rods

8 - 1 1/2” Sinker Bars• Well Started on 1/12/2009 and has not had

rod failures since then.

Conclusion• Customer feedback indicates a lack of balance between the

KD and HS rods (Better load carrying capabilities than KD rods and better ductility than HS rods)

• SD rods are 33% stronger than KD rods and 12% tougher than HS rods.

• SD rods fills the application gap between a KD and HS rods.

• 12 test wells indicate improvements in rod performance after using SD rod string.

Sept. 14 - 17, 2010 2010 Sucker Rod Pumping Workshop 24

Copyright

Rights to this presentation are owned by the company(ies) and/or author(s) listed on the title page. By submitting this presentation to the Sucker Rod Pumping Workshop, they grant to the Workshop, the Artificial Lift Research and Development Council (ALRDC), and the Southwestern Petroleum Short Course (SWPSC), rights to:

– 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.– Place it on a CD for distribution and/or sale as directed by the Workshop

Steering Committee.

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. 14 - 17, 2010 2010 Sucker Rod Pumping Workshop 25

DisclaimerThe 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.The views, opinions, and conclusions expressed in these presentations and/or training materials are those of the author and not necessarily those of the Sponsoring Organizations. The author is solely responsible for the content of the materials.The Sponsoring Organizations cannot and do not warrant the accuracy of these documents beyond the source documents, although we do make every attempt to work from authoritative sources. The Sponsoring Organizations provide these presentations and/or training materials as a service. The Sponsoring Organizations make no representations or warranties, express or implied, with respect to the presentations and/or training materials, or any part thereof, including any warrantees of title, non-infringement of copyright or patent rights of others, merchantability, or fitness or suitability for any purpose.