The Ultimate PCP Rod Solution

EHT ®

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EHT – Designed for PCP Conventional approaches of adopting or modifying traditional sucker rod for PCP application often came short in meeting the higher torque and other unique re-quirements of PCP. In 2006, engineers at Exceed Oilfield Equipment started re-search and development of a PCP spe-cific rod. The current generation EHT features patented locking dove-tail con-nection and case hardened rod body. Overall, it offers 20-30% higher torque. Customers switched to EHT have seen benefits of reduced load, improved oper-ating efficiency and lowed failure rate.

Adapting existing rod

Modify coupling thread

Increased body size

Other

Approaches

Case hardened body

Dove-tail lock connection

Anti-tripping coupling

EHT

Rod Size Maximum Torque

(Nm)

7/8" 1800

1" 2100

1-1/8" 4100

Dove-tail keyed rod boy lock together

Torque on rod body, not coupling thread

Coupling holds rods together only

10% martensitized surface layer

Higher torque

Anti-plastic deformation, shear resisting

When adopting EHT, customer often re-

place existing 1” rod with 7/8” EHT for re-

duced load and higher operating efficiency.

vs

©2011-2013 Exceed Oilfield Equipment Inc. All rights reserved EHT - The Ultimate PCP Rod Solution. April, 2014

7/8” EHT® offers higher maximum torque than competitor’s 1” PC Rod

When designing an artificial lift system with a Progressive Cavity Pump (PCP), the Maxi-mum Torque offered by the sucker rod is the most import parameter to consider dur-ing rod selection. Exceed Oilfield Equip-ment’s EHT® rod dwarfs the competitions when compared the torque value. Compar-ing to competitor’s 1” PC rod, 1” EHT of-fers 35% higher torque. The 7/8” EHT rod, despite having a 24% smaller body size, still delivers 10% higher maximum torque value compared to 1” drive rod from competition. This allows customers who are currently using 1” drive rod two alternative options, switch to 1” EHT for signifi-cantly increased reliability or 7/8” EHT for much more efficient operation.

Figure 1: EHT PC Pump rod with patented dove-tail connection

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4100

2200

1800

3390

1627

0

1000

2000

3000

4000

5000

1-1/4" 1-1/8" 1" 7/8"

Exceed EHT® Rod

Drive Rod (97)

Figure 2: Maximum torque value comparison - EHT vs. DR97

Rod

Sting

Weight

25

%

Overall

Load

10

%

Pump

Life

Time

50

%

7/8” EHT Replace 1” Benefits

Produc-

tion

Efficiency Imp

rove

EHT Parameters

Tensile Strength

(MPa)

Surface Hardness

(HRC)

Center Hardness

(HB)

Surface Residual

Compressive Stress (Mpa)

Maximum Torque

(rod size)

Maximum Torque (Nm)

Torsion Strength

(Nm / m2)

999-1290 ≥42 ≥224 ≤200

7/8" ≥1800

≥1000 1" ≥2200

1-1/8" ≥4100

©2011-2013 Exceed Oilfield Equipment Inc. All rights reserved EHT - The Ultimate PCP Rod Solution. April, 2014

In a PCP oil/liquid production system, instead of ax-ial force, the rod string, which consist of sucker rod and couplings, transfers circumferential torque from surface motor to down-hole pump. This torque peaks dur-ing surface motor starting, and reverses and valleys when the motor stop. This flip-flopping circumferential torque creates significant challenges to sucker rod with traditional design, particularly to the thread connection between the coupling and rod. In a traditional rod connection, com-monly used by Exceed competitions, the thread between coupling and rod are designed mainly to withstand stress in axial direction.

During PCP’s operation, the rod string works under cons circumferential stress. This can cause the rod / coupling connection to fail in two fashions. When the torque ex-ceeds the coupling torque in counter-clock direction, the coupling start to over torque. When the torque is clock-wise, the thread start to lose displacement. Coupling/rod pin failure are common result in either case.

Figure 3: Traditional design - circumferential and axial stress Both apply to coupling threads

EHT’s patented dove-tail connection solves the threading problem by isolating the circumferential torque transfer-ring to rod body. The coupling is no longer under both circumferential stress and axial stress, which is the root cause of many PCP rod failures.

Figure 4: Coupling failure due to clockwise circumferential stress / loss of displacement

The EHT coupling threads only bear minimum axial stress from the weight of the rod string and pump. Inside the connection, a reverse threaded stop ring and spring washer guarantees the coupling holds the rods in place.

Figure 5: EHT isolate circumferential torque to dove-tailed rod body and axial stress to coupling.

Varying circumferential stress in PCP operation create challenges to the rod body too. When the driving surface motor stops, the pump down-hold are still rotating at its operating speed. The momentum “twist” the rod string and often result in rod body failures. This is particularly a problem for normalized and tempered rod which have good elasticity.

To create a strong body, EHT rod underwent an special additional heat treatment process - the induction case hardening. After the initial whole body heat treatment, the rod body surface layer is heated up again by induction and then quenched and tempered. In this secondary heat treat-ment process, martensite transformation creates a hard case in the rod body. This significantly improves the ten-sile strength of the body while the softer core keeps the overall elasticity.

Figure 6: Illustration of induction heating

Figure 7: EHT body showing case-hardened cross-section

Figure 8: EHT body showing case-hardened wrench flat

INSIDE EHT®

Page 4 ©2011-2013 Exceed Oilfield Equipment Inc. All rights reserved EHT - The Ultimate PCP Rod Solution. April, 2014

CA

SE

S

TU

DI

ES

CASE STUDY – 1

Before switched to 7/8” EHT, customer experienced frequent rod failures using 1” conventional de-

sign sucker rod. On average the rod need to be replaced every 6 month due to failure. After switched to

EHT on Aug 16th, 2011, this well has not experienced any rod failure since.

USE 7/8” EHT TO REPLACE 1” CONVENTIONAL ROD

Reduce rod string weight >25%

Reduce overall load >10%

E H T ® B E N E F I T S

CASE STUDY – 2

Before switched to 7/8” EHT, customer experienced frequent rod failures using 1” conventional de-

sign sucker rod. On average the rod need to be replaced every 6 month due to failure. After switched to

EHT on Dec 6th, 2010, this well has not experienced any rod failure since.

CASE STUDY – 3

Before switched to 7/8” EHT, customer experienced frequent rod failures using 1” conventional de-

sign sucker rod. On average the rod need to be replaced every 6 month due to failure. After switched to

EHT on Aug 15th, 2012, this well has not experienced any rod failure since.

Increase pump lifetime >50%

Reduce production cost

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Well Name: PS-2735

PC Pump: GLB300

Pump Depth: 951.05m

Rotor Speed: 100 rpm

Product Rate: 22 T/day

Original Configuration

EHT Configuration

Rod Size: 1” 7/8”

Rod Weight: 4083.04 kg 3103.36kg

Generator: 22KW/20A 15KW/11A

Well Name: PS-2735

PC Pump: GLB400

Pump Depth: 951.05m

Rotor Speed: 75 rpm

Product Rate: 21 T/day

Original Configuration

EHT Configuration

Rod Size: 1” 7/8”

Rod Weight: 3847.48 kg 2924.32 kg

Generator: 22KW/20A 15KW/11A

Well Name: PS-2737

PC Pump: GLB300

Pump Depth: 1121.89m

Rotor Speed: 100 rpm

Product Rate: 22 T/day

Original Configuration

EHT Configuration

Rod Size: 1” 7/8”

Rod Weight: 4828.98 kg 3103.36kg

Generator: 22KW/20A 15KW/11A

©2011-2013 Exceed Oilfield Equipment Inc. All rights reserved EHT - The Ultimate PCP Rod Solution. April, 2014