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TRANSCRIPT
September 2007
ALRDC/SWPSC 2007 InternationalSucker Rod Pumping WorkshopPRO/KC Four Piece Sucker Rod Connection
Brian Waterhouse
1© 2006 Weatherford. All rights reserved.
Four Piece (PRO/KC) Connection Outline
• Back Ground
• Connection Detail
• Connection Laboratory Testing
• Neck Stretch vs. Circumferential Displacement
• Field Trial Back Ground Information
• Field Trial Results
• Summary
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PRO/KC Connection
• Sucker rod connection failures are one of the most common reasons for Reciprocating and PC Pump well intervention. They can lead to expensive well servicing costs and lost production.
• Too many times the make-up procedures used in the field are very lax. Not enough time and attention is put into making up these connections properly. This leads to premature failures of the connection.
• PRO/KC API modified design and make-up system provides the industry a sucker rod connection that is stable with simple field make-up.
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PRO/KC Connection Detail
What is the PRO/KC Connection?
This is a four piece sucker rod connection consisting of:
• A modified API sucker rod pin with precision make-up.
• A modified API sucker rod coupling.
• A torque button.
• A modified API sucker rod pin with field make-up.
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PRO/KC Connection Detail
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PRO/KC Connection Detail
• Pins machined to precise length
• Couplings machined to precise length
• Torque button inserted at coupling center
• Neck stretch make-up method used
US Patent #6,942,254 B2
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PRO/KC Connection Detail
Torque button made from dissimilar material to eliminate galling & clutching
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PRO/KC Connection Detail
Pins are machined to a precise length tolerance
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PRO/KC Connection Detail
Couplings are machined to a precise length tolerance
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PRO/KC Connection Detail
Precision Coupling Make-up
Pin Stretch Verification
Precision Pin Neck Loading
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PRO/KC Connection Lab Testing
Laboratory testing performed at CFER Labs in Edmonton Alberta, Canada.At 20,000 LB. tension and torque to failure, PRO/KC averaged 250% more torque to failure than API connections
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PRO/KC Connection Lab Testing
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PRO/KC Connection Lab Testing
Fatigue testing performed by Southwest Research Institute in San Antonio.
A combined total of 30 API and PRO/KC samples were put into 69,500 lb. Tension and 7800 lb. Compression, at 10 cycles per second.
PRO/KC averaged 6 times more cycles to failure than the API Connections.
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PRO/KC Connection Lab Testing
• Finite Element Analysis used to optimize geometry and make-up process
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PRO/KC Connection Lab Testing
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PRO/KC Connection Lab Testing
• 1” Stress Concentration / Amplification
Load Case
Peak Stress @ First En- gaged Pin Thread
Mean StressDue To
Make-up
Nominal
Rod Stress
SCF
SAF
3 37,500 lbs Tension
126,844 psi
123,968 psi
47,794 psi
2.65
.060
4 27,500 lbs Tension
125,663 psi
123,968 psi
35,039 psi
3.59
.048
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PRO/KC Connection Lab Testing
• 7/8” Stress Concentration / Amplification
Load Case
Peak Stress @ First En- gaged Pin Thread
Mean StressDue To
Make-up
Nominal Rod
Stress
SCF
SAF
3 18,500 lbs Tension
126,507 psi
126,927 psi
30,765 psi
4.11
.000
4 28,500 lbs Tension
126.024 psi
126,927 psi
47,395 psi
2.66
.000
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PRO/KC Pin Neck Stretch vs. CD
1
47483
Displacement 22
3/4
1/81/4
7/8
3/81/2
5/8
29794
2111
01
5
1" rodpin
distances beyond displacement to achieve proper
neck stretch
rod counts
-pin nose-
-shoulder contact face-
1
47483
Displacement 22
3/4
1/81/4
7/8
3/81/2
5/8
29794
2111
01
5
1" rodpin
distances beyond displacement to achieve proper
neck stretch
rod counts
-pin nose-
-shoulder contact face-
Circumferential displacement versus Pin Neck Stretch.
Rods Analyzed 980 - 1in. High strength with Class T Couplings
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PRO/KC Pin Neck Stretch vs. CD
1
Displacement73
3/4
1/81/4
7/8
3/81/2
5/8
01
7/8" rodpin
515471115
8313
0
distances beyonddisplacement toachieve proper
neck stretch
rodcounts
-pin nose-
-shoulder contact face-
1
Displacement73
3/4
1/81/4
7/8
3/81/2
5/8
01
7/8" rodpin
515471115
8313
0
distances beyonddisplacement toachieve proper
neck stretch
rodcounts
-pin nose-
-shoulder contact face-
Circumferential displacement versus Pin Neck Stretch
Rods Analyzed 1270 - 7/8in. High strength with Class T Couplings
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PRO/KC Pin Neck Stretch vs. CD
• Threading roll tap wear and form change causes gradual pin load flank to box load flank mismatch yet remains within API dimensional tolerances
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PRO/KC Connection
PRO/KC design provides a connection with:
• Equal contact pressure of both pin shoulders
• Equal pre-load stretch of both pin necks
• Equal contact pressure of both pin noses against the center torque button
• Pre-load stretch at the coupling center
• Strongest, most stable connection in tension, torsion, bending, and fatigue
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PRO/KC Connection
• Simple easy field install procedures.
•No measuring circumferential displacement and recalibrating tongs
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Field Background Information
Field Trials of the PRO/KC Sucker Rod Connection in an RRP Application
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Field Background Information
• NAL’s Field is located near Estevan in south eastern Saskatchewan, Canada and has been operating for 30 years.
• Field consists of 19 active wells.
• 16 Wells are pumped with an RRP and the remaining wells are pumped with ESP pumps.
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Field Background Information
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Field Trial Well Information
Test Well Conditions:
• Well Type: Horizontal
• Static Pressure: 12,000 kpa (1740 psi)
• Total Depth: 2214 m (7260 ft)
• Perforations: 1262 m (4140 ft)
• Casing: 7”
• Tubing 3-1/2” lined
• Pump is landed at kick off above the perforations.
• Tubing is not sumped below the perforations.
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Field Trial Well Information
Test Well Fluid Conditions:
• Oil Gravity: 34 API
• Water Cut : 99%
• Total Produced Fluid: 101.9 m3/d (640 BFPD)
• CO2 : 5.5% of gas stream
• H2S: ~100 ppm
• GOR: 95 scf/bbl
• Well is very corrosive and is on a continuous chemical program of 6 l/d corrosion inhibitor.
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Field Trial Well Information
Test Well Equipment:
• Pump Jack: Rotoflex 900
• Pump Speed: 1.8 spm
• Stroke Length: 288”
• Pump Size: 30-375-RX-34-2-4Over Sized Tubing Pump
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Field Trial Well History
Test Well Intervention History
• From August 2005 to March 2006 had three sucker rod failures averaging 2.7 months between failures.
• March 2006 NAL installed 1” EL sucker rod with PRO/KC connections.
• September 2006 RRP standing valve fails. Rerun EL sucker rods and PRO/KC connections and this well continues to produce. This string has operated for 17 months.
• Workover costs to replace or repair parted rods is on average $15,000.
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Field Trial Results
Test Well Results To Date:
• PRO/KC connection has increased the sucker rod run life from an average of 2.7 months to 17+ months.
• Based on previous average run life, NAL’s YTD Service Rig cost savings is approx. $90,000.
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Field Trial Results
Other RRP PRO/KC Field Trials:
• Large Independent Oil Company
• Equipment
– Beam Pump Unit is a 1280 with a 288” stroke length operating at 8 spm. PPR load is 48,000+ lbs.
– RRP Pump is a 2” bore
• Intervention frequency with standard API couplings averaged 56-63 days.
• Run time with the PRO/KC connection is 445 days with no failures.
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Summary
• New PRO/KC connection design and make-up process exhibited successful lab testing.
• Being field tested in RRP pump operations with a history of rod breaks.
• NAL field trial has seventeen+ months run time compared to previous MTBD of 2.7 months.
• Initial results show potential to reduce connection failures in problem wells.
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Acknowledgments
NAL Oil & Gas Trust
Permian Rod Operations
Weatherford