Development and field experience of 7/8” with 1” pin sucker rods Use of UHS couplings

Beam Pumping WorkshopHouston, Texas

October 4 - 7, 2005

Development and field experience of 7/8” with 1” pin sucker rodsUse of UHS couplings

Alejandro F. Ameglio – Head Technical Services

Tenaris Rods Division

April 22, 2023 7/8” with 1” sucker rods – UHS Couplings 2

Field statistics - HistoryConceptDevelopmentField experiencesField evolutionConclusions

Contents7/8” with 1” pin sucker rods

ConceptDerating factorsTechnical DataField experienceConclusions

UHS Couplings

7/8” with 1” pin sucker rods – UHS Couplings


This idea is a result of a team work between a major operating company from Argentina (Pan American Energy) and TenarisPan American Energy operates Cerro Dragón Field (south of Argentina)Field data Total amount of producing wells: 2193 (7200-8500 ft) Total Production rate: 123 Mm3/d (774 Mbfpd) Total oil rate: 13,7 Mm3/d (86,2 Mbfpd) Total rod pumping wells: 1718

Introduction7/8” with 1” pin sucker rods


Introduction

Rod pumping wells

Depths: 2193 (7200-8500 ft)

Production rates: 120-200 m3/d (750-1250 bfpd)

7/8” with 1” pin sucker rods


Due to a secondary recovery process started in 1988, fluid production rates have been continuously raising.

This increased the loads levels, and the failures rates at rod strings

Introduction

Evolución de la Producción e Intyección en Cerro Dragón

0

10000

20000

30000

40000

50000

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Jan-80

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Jan-86

Jan-88

Jan-90

Jan-92

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Jan-96

Jan-98

Jan-00

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Jan-04

m3/

d

Fluido [m³/d] Petróleo [m³/d] Inyección [m³/d]



Field HistoryFailures evolution

0

0.05

0.1

0.15

0.2

0.25

1984/87 1988/91 1992/95 1996/98Years

IPA

Rods Pumps Tubingwells_of_amount_TotalonsInterventi_WellIPA =




050

100150200250300350400450500

1984/87 1988/91 1992/95 1996/98Years

Qty

. of

failu

res

1" 7/8" 3/4"




0

50

100

150

200

250

300

350

1984/87 1988/91 1992/95 1996/98Years

Qty

. of

failu

res

Body Pin Coupling

Main problem to solve 7/8” pin failures



Concept - Ideas7/8” with 1” pin sucker rods


Analyzing the problem7/8” with 1” pin sucker rods

As a first step, all the factors involved in the problem were analyzed

Make up practices Training program applied / Control and Inspection at wellhead

Make-up torque control method

Use of displacement cards (API circumferential displacement method)

Pin pre-tension increment (new torque card)

Lab studies to determine the optimum circumferential displacement for Grade D rods

After all 7/8” pin failures rates still going up!!!


Analyzing the problem7/8” with 1” pin sucker rods

At second stage, different alternatives were evaluated

New threaded connection for sucker rods

Not easy. Long times of development required

Material’s resistance increasing

There were as much pin failures in HS rods as in Grade D

THE OIL MEN’S SOLUTION

MAKE IT BIGGER!!!


Solution“The objective was to strenghten the cross section at the stress relief zone for the 7/8” rods”

Concept - Ideas

Sucker Rod diameter (OD)

Rod body area (cross-section)

Rbody

Rod pin area (cross-section) at the stress relief

Rpin

Areas Ratio (Rpin / Rbody)

Inch Inch2 Inch2

¾ 0.44 0.66 1.5

7/8 0.60 0.85 1.41 0.79 1.18 1.5



Concept - IdeasHOW?

Making a 7/8” rod with 1” pin

Development of a new forging technique

For fatigue resistance, steel fibers must “copy” the external shape of the elementCutted or whirled steel fibers result in a fatigue failure



7/8” with 1” pin rods – First attempts7/8” with 1” pin sucker rods


7/8” with 1” pin rods – Forging process7/8” with 1” pin sucker rods


7/8” with 1” pin rods

Detail of a 7/8” with 1” pin sucker rod showing the steel fibers



7/8” with 1” pin rods

Comparison between 7/8” API vs. 7/8” with 1” pin rods



Field experienceWells installed – First Lot of field tests

Well Date Qty of rods inst. Service life (days)A Oct-98 80 1499B Oct-98 85 1684C Oct-98 87 2538D Nov-98 81 2507E Dec-98 95 2477F Dec-98 54 2477G Dec-98 83 2477H Jan-99 51 2446I Feb-99 75 2415J Feb-99 84 2415K Mar-99 94 2387L Mar-99 70 2387M Apr-99 55 2356

14 Wells TOTAL 994

A first lot of 1000 7/8” with 1” pin were installed



Field experience – Well #AWell Date Cause of Intervention Comments

A 29/06/1982 Rod String Break 7/8” pin break

17/05/1986 Rod String Break 7/8” pin break









7/10/1998 Rod String Break 7/8” pin break – 7/8” with 1” pin INSTALLATION

14/11/2002 Rod String Break FIRST 7/8” WITH 1” PIN FAILURE

IPA (index) before the installation of 7/8” – 1” pin rods: 0.66IPA (index) after the installation of 7/8” – 1” pin rods: 0.24Average running time of conventional API 7/8” rods: 502 daysRunning time of 7/8”-1” pin rods: 1499 days – 17 MM cycles



Field experience – Well #B

Well Date Cause of Intervention CommentsB 13/Oct/1995 Rod String Break 7/8” pin break

17/Dec/1996 Rod String Break 7/8” pin break

23/Ago/1997 Rod String Break 7/8” pin break

21/Oct/1998 Rod String Break 7/8” pin break – 7/8” with 1” pin INSTALLATION

1/Jun/2003 Rod String Break FIRST 7/8” with 1” pin FAILURE

IPA (index) before the installation of 7/8” – 1” pin rods: 1.30

IPA (index) after the installation of 7/8” – 1” pin rods: 0.21

Average running time of conventional API 7/8” rods: 368 days

Running time of 7/8”-1” pin rods: 1684 days – 19 MM cycles



Field experienceWell Date Qty of rods Service Life

1 Jan-00 70 21042 Feb-00 75 20733 Feb-00 75 20734 Feb-00 86 20735 Feb-00 66 20736 Apr-00 76 20137 May-00 70 19838 May-00 87 19839 May-00 87 198310 May-00 94 198311 Jun-00 88 195212 Jul-00 60 192213 Jul-00 82 192214 Jul-00 70 192215 Jul-00 76 192216 Aug-00 83 189117 Aug-00 77 189118 Oct-00 83 183019 Oct-00 100 183020 Oct-00 72 183021 Oct-00 65 183022 Oct-00 94 183023 Nov-00 88 179924 Nov-00 85 179925 Dec-00 97 176926 Jan-01 95 173827 May-01 90 161828 Jul-01 80 1557

28 Wells TOTAL 2271

Wells installed – Second lot of field tests



Field evolution7/8" Sucker Rod Failures

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

1980/83 1984/87 1988/91 1992/95 1996/98 1999/2002

No.

of F

ailu

res

Pin Body Coupling



The new product, fruit of the teamwork between Pan American Energy and Tenaris, has largely overcome the most optimistic expectations.

A 30% reduction in the pin failures was achieved, considering the total amount of oil wells with rod pumping lift systems.

If we referred only to the wells that have this solution, we have reduced the IPA (index of intervention per well per year) approximately in five (5) times.

Today the use of these rods has became standard for all oil well deeper than 2000 mts and with high producing rates,

An increasing of 30% in the fatigue resistance capacity of this rods is only the first step. That conduct us to develop a new premium threaded connection applicable to all of the API conventional rods.

Conclusions7/8” with 1” pin sucker rods


Another problem to solve was the one related with failures in 1” SH (Slim Hole) couplings

This problem could be analyzed according with:

Use of 1” SH Class T couplings with Grade D rod strings

Use of 1” SH Class T couplings with HS (High Strenght) sucker rod strings

It is well known that SH (Slim Hole) couplings has to be affected by a derating factor in their allowable stress calculations

IntroductionUHS Couplings (Ultra High Strength)


Derating Factors for SH couplings

API SH Coupling Size

Derating Factors for Rod Grades

in K C D HS5/8” - 0.97 0.77 0.633/4” - - 0.86 0.707/8” 0.93 0.88 0.69 0.571” - - 0.89 0.74

UHS Couplings (Ultra High Strength)

According to Bradley (Petroleum Engineering Handbook) and Hermanson (LTV Energy), use of SH couplings requires the use of a derating factor that affect the max. allowable stress of the string


Analyzing the problem UHS Couplings (Ultra High Strength)

Problem to solve:1” API SH Couplings

failures

Possibility to use 1” API FS

Couplings

Increase the Couplings resistance

UHS Couplings

No derating factors required

YESGeometry problems(Tubing 2 7/8”)

NO


Technical DataUHS Couplings (Ultra High Strength)

Coupling Grade/Type

Hardness tests

UTS

HRC MPa Ksi

API Class T 16-23 655 95 MínUHS 30-34 980 140 Mín



Field experience – Field “A”UHS Couplings (Ultra High Strength)

A major independent producer from Argentina operates a field in Neuquén Basin.

Well Characteristics Depths: 6500-8500 ft (2000-2600 m)

Fluid rates: 310-890 bfpd (55-140 m3/d)

This field is operated by rod pumping system (250 wells).

Main problems to solve are related with 7/8” pins and 1” API Class T SH couplings failures


Field experience – Field “A”UHS Couplings (Ultra High Strength)

1" SH Couplings failures

0

1

2

3

4

Date

Qty

of f

ailu

res

1" SH Couplings failures

UHS Couplings



xxB-95 18-Feb-99 1” coupling failure16-Mar-99 Pump failure22-Apr-99 1” coupling failure03-Aug-99 ¾” rod pin break04-Nov-99 WO30-Nov-99 7/8” rod pin break11-Jul-00 1” coupling failure02-Jan-02 1” coupling failure UHS Couplings

Installation22-Jun-02 Polished rod break07-Jan-03 ¾” rod pin break

IPA (index) before the installation of UHS 1” SH couplings: 1.03IPA (index) after : 0.8Largest time in service before UHS couplings: 540 daysRunning time of UHS 1” Sh Couplings pin : 1350 days – 23 MM cycles


Average service life for 1” SH API Class T couplings

350 days

Service life for 1” UHS SH couplings

1350 days



xxB-127 8-Apr-99 ¾” rod pin break12-Apr-99 ¾” rod body break14-Jun-99 7/8” rod pin break9-Jul-99 Pump failure3-Jan-00 1” coupling failure18-Jan-00 1” coupling failure11-Mar-00 7/8” rod pin break17-Aug-01 1” rod body failure8-Feb-02 Polished rod break29-Mar-02 1” rod pin break3-Apr-02 ¾” rod body break15-Aug-02 1” coupling failure UHS Couplings

Installation

Largest time in service before UHS couplings: 940 daysRunning time of UHS 1” Sh Couplings pin : 1125 days – 14.7 MM cycles


Average service life for 1” SH API Class T couplings

408 days

Service life for 1” UHS SH couplings

1125 days


Field experience – Total of wellsWell Date Service Life

months

Fatigue CyclesMM cycles

Fluid ratebfpd (m3/d)

xxB-017 10-Jul-00 63.1 23.7 346.4 (55)

xxB-028 31-Oct-00 59.3 10.8 554.2 (88)

xxB-160 5-Jan-01 57.1 18.0 226.7 (36)xxB-228 8-Jan-01 57.0 20.9 251.9 (40)xxB-180 5-Dec-01 46.0 16.9 692.7 (110)xxB-095 3-Jan-02 45.0 17.9 566.8 (90)

xxB-172 27-Mar-02 42.2 13.7 314.9 (50)xxB-127 15-Aug-02 37.5 14.7 503.8 (80)xxB-001 11-Oct-02 35.6 12.9 503.8 (80)xxB-178 7-Mar-03 30.7 12.6 629.8 (100)

xxB-111 7-May-03 28.7 6.2 881.7 (140)xxB-038 22-Sep-03 24.1 9.1 598.3 (95)xxB-142 6-Feb-04 19.5 3.5 472.3 (75)

xxB-187 18-Jun-04 15.1 2.7 440.8 (70)



Rod pumped wells with high loads could experience failures at sucker rod strings that increase the operative costs of the field.

Assuming a good h&c and make-up practices, that failures are (in general) related with the mechanical resistance of the materials involved.

Both experiences presented are the result of a task force that involves the operators and suppliers (manufacturers).

Those products had shown a very good performance. An important reduction in the number of well interventions, as well as downtimes associated result in a cost reduction for those fields.

The simplicity of these solutions make them easily applicable to diverse well conditions.

ConclusionsUHS Couplings (Ultra High Strength)


Questions

THANKS !!!

Development and field experience of 7/8” with 1” pin sucker rods Use of UHS couplings

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