Partial History of the Industry

Transcription

1 5 th Annual Sucker Rod Pumping Workshop Wyndham Hotel, Dallas, Texas September 15 18, 2009 Circumferential Displacement Partial History of the Industry Practice Russell Stevens, Manager Technical Services, Norris and Norman W. Hein, Jr., P.E., President & Managing Director, Oil & Gas Optimization Specialists, Ltd. (OGOS)

2 Contents Recent testingti 3 prior testing phases; 1968, 1984 & 1989 and results Other testing ti Factors that affect bolted joint forces and effectiveness Conclusions & Recommendations 2009 Sucker Rod Pumping Workshop 2

3 Recent Tests on Rod Make-up The history of the make-up tests that resulted in the use of circumferential displacement (CD) is due to the known fact that torque has been proven to be an inaccurate make-up method mainly due to over-coming the various friction factors including: Surface finish effects Lubrication effects Tests have been conducted these past few years but without complete understanding of the prior work and the establishment of the requirements that have been adopted by the industry in API RP 11 BR 2009 Sucker Rod Pumping Workshop 3

4 Recent Tests (con t) Part of the problem is that unless you were a member of the API task group, you didn t see the actual tests and results. The only thing permanently remembered was what had been accepted by the industry and adopted in the standard The other part of the problem is that Dover-Norris had not published the many different tests programs and results, until now 2009 Sucker Rod Pumping Workshop 4

5 1968 Tests - The Original Geek Squad 2009 Sucker Rod Pumping Workshop 5

6 1968 (con t) 2009 Sucker Rod Pumping Workshop 6

7 1968 (con t) Measuring equipment consisted of: BLH Electronics Channel input board Switching & balancing unit Strain indicator unit Dillon 1000 pound dynamometer to obtain applied torque knowing fixed lever arm of 12 inches Micro Measurements ES ED-120 w/le option strain gauges 3 gauges used place 120 o around undercut after drilling thru pin upset to run leads & to assure threaded connection had 100% integrity 2009 Sucker Rod Pumping Workshop 7

8 1968 Tests Equipment Setup 2009 Sucker Rod Pumping Workshop 8

9 1968 (con t) Channel Inputs Switching & Balancing Unit Strain Indicator Unit 2009 Sucker Rod Pumping Workshop 9

10 1968 (con t) Connection Makeup (NOTE: strain gauge lea 2009 Sucker Rod Pumping Workshop 10

11 1968 (con t) 2009 Sucker Rod Pumping Workshop 11

12 1968 (con t) The results of these tests were provided to the API task group that consisted of: B. R. Bruton (Chairman) Lee Current (Oilwell) Dean Hermanson (Continental-Emsco) Robert A. Morris (Dover Norris) C. R. Neilson (National Supply) They accepted the Norris work on June 10, 1968 based on the following example graphs to provide approximately 40,000 to 45,000 psi of pin pre-stress Results published in API RP 11BR 2009 Sucker Rod Pumping Workshop 12

13 1968 (con t) ½ 5/8 ¾ 7/ / Sucker Rod Pumping Workshop 13

14 1968 (con t) 2009 Sucker Rod Pumping Workshop 14

15 1984 Tests Investigated t rerun make-up effects Investigated face contact effects (full sized vs. slim hole couplings) Investigated lubrication effects (pin only and pin & face) 2009 Sucker Rod Pumping Workshop 15

16 1984 Tests Equipment Setup 2009 Sucker Rod Pumping Workshop 16

17 1984 (con t) 2009 Sucker Rod Pumping Workshop 17

18 1984 (con t) 2009 Sucker Rod Pumping Workshop 18

19 1984 (con t) Results Rerun Grade C (Type 30) 2009 Sucker Rod Pumping Workshop 19

20 1984 (con t) Results Rerun Grade D (Type 78) 2009 Sucker Rod Pumping Workshop 20

21 1984 (con t) Results 3/4 Type 78; Pin Lubed 2009 Sucker Rod Pumping Workshop 21

22 1984 (con t) Results 3/4 Type 78 Pin & Face Lubed 2009 Sucker Rod Pumping Workshop 22

23 1984 (con t) - Results Verification of CD required for ~40 ksi for C grade and ~68 ksi for D grade pin prestress If slim hole coupling run, increased torque/cd is required to obtain same pin prestress as full size coupling face If pin & face are lubricated, the required torque/cd is greatly reduced; however, concern is expressed if pin prestress is retained since contact area was insufficiently burnished Results provided to API and changes to RP 11BR resulted in recommendation to keep connection clean and only lubricate pin along with values for make-up 2009 Sucker Rod Pumping Workshop 23

24 1989 Tests Investigate t make-up requirements for non-api, extra high strength grade (Norris 97) and compare to similar diameters of API grades C & D Used same testing set-up, equipment and strain gauges Better photos follow of drilled upset end showing leads and gauge placement 2009 Sucker Rod Pumping Workshop 24

25 1989 Tests 2009 Sucker Rod Pumping Workshop 25

26 1989 (con t) 2009 Sucker Rod Pumping Workshop 26

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28 Other Testing Conducted Joint make-up CD (and resulting torque) versus fatigue life Values of 50, 100 and 150% of API recommendations Load range 20 to 40 ksi Fatigued in air 2009 Sucker Rod Pumping Workshop 28

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30 Machine Design May 21, 1987 Bolted joint clamping-force variables Application was multi-bolt connection (flange) Forces and most reasons for joint force modification are applicable to sucker rod connection The following flow chart, divided into 3 slides, show the analysis of bolted connections 2009 Sucker Rod Pumping Workshop 30

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34 Make-up Summary Many parameters affect joint strength and capacity. These include: Skill of operator Original make-up loads/pin prestress Overloads In-service failures Loosening under mechanical action, i.e., vibration, buckling, contact/wear (Norm Hein s example of loosening pickle jar lid) Thermal effects Many of these are applicable to sucker rod threaded connections 2009 Sucker Rod Pumping Workshop 34

35 Conclusions & Recommendations Many tests have been conducted over the past 40 years to investigate sucker rod connection make-up Minimum values have been determined to provide pin prestress of approximately 40 ksi for Grade C; 68 ksi for Grade D and 88 ksi for HS rods. However, since yield strength of the actual rod materials are typically >10% more than minimum, more CD would be required to obtain adequate make-up This added d CD is normally accounted for in the manufacturers CD card versus just using minimums in API RP 11BR 2009 Sucker Rod Pumping Workshop 35

36 Conclusions & Recommendations (con t) Thus, it is recommended to use manufacturer s CD card for their specific rod grades If applied stresses are greater than pin prestress, connection separation will occur These loads may not be recorded by dynamometer investigation, but impact loads from pounding fluid (liquid and/or gas) greatly magnifies actual loads Proof is in the connection; since no liquids were pumped into coupling when made up, if liquid pours out when disconnected, joint is coming apart downhole 2009 Sucker Rod Pumping Workshop 36

37 Conclusions & Recommendations (con t) Condition of thread form is important to assure applied make-up forces are evenly distributed Lubrication of pin only assures adequate make-up and contact face burnishing to help keep prestress applied If slim-hole couplings are used, more CD/torque should be applied to assure required pin prestress is applied Most manufacturers have not accounted for the face contact area in their CD recommendations 2009 Sucker Rod Pumping Workshop 37

38 Conclusions & Recommendations (con t) Other testing on connection make-up showed the improvement in fatigue life; but, in the field, these improvements may still be lost depending on operating practices (pounding fluids, tagging bottom, over- pumping the well, etc.) Many of the parameters and resulting reasons why threaded connections fail are analogous to other threaded components Main reasons for failures include: skill of operator making connection, applied load excursions, vibration/ buckling, thermal effects, and in-service failures (failures cause other failures especially if all connections are not remade) 2009 Sucker Rod Pumping Workshop 38

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41 Circumferential Displacement Partial History of the Industry Practice Russell Stevens, and Norman W. Hein, Jr., P.E., and