Evaluation and Testing of Mechanical Cement Wiper Plugs

API TECHNICAL REPORT 10TR6 FIRST EDITION, JULY 2015

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Contents

Page

1. Scope 1

2. Normative References 1

3. Terms and Definitions 1

4. Purpose of Mechanical Cementing Wiper Plugs 3

   1. General 3

   2. Fluid Separation 3

   3. Wiping the Inner Surface of the Pipe 4

   4. Downhole Tool Operation 5

   5. Event Indication 5

   6. Temporary Pressure Barrier 7

5. Background Information 7

   1. Short and Long Fin Plugs 7

   2. Combination or Multiple Diameter Fin Cementing Plugs 7

   3. Other Wiping Mechanisms 8

   4. Launching Methods and Apparatus 9

   5. Landing Seats for Mechanical Cementing Plug 14

6. Possible Failure Modes of Cementing Wiper Plugs 15

   1. General 15

   2. Debris in or Condition of Pipe 15

   3. Poor Wiping Efficiency 16

   4. Fluid Bypassing 16

   5. Failure to Launch 16

   6. Improper Installation Order of Cementing Plugs in Cementing Head 17

   7. Construction Defects 17

   8. Plug Damage 18

   9. Incorrect Diaphragm Pressure Selection 19

   10. Hostile Storage Environment 20

   11. Misapplication of Cementing Plugs 21

   12. Plug Deformation 23

   13. Crossover or Transitions 23

7. Mechanical Cementing Plug Construction 23

   1. Surface-launch Plugs 23

   2. Liner (Wiper) Plug Systems 25

   3. Subsea-released (Launched) Plugs 26

8. Evaluation of Mechanical Cementing Plugs 27

   1. General 27

   2. Standard Test Method for Elastomer Property—Effect of Liquids 27

   3. Bottom Plug Rupture (Flow Through) Static Pressure Test Procedure 28

   4. Bottom Plug Rupture (Flow Through) Dynamic Pressure Test Procedure 31

   5. Plug Fin Bypass Pressure Test Procedure 32

   6. Plug Pressure Integrity Testing 33

   7. Latch In and Out Test Procedure 34

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      Contents

      Page

   8. Plug Fin Wear Test Procedure 38

   9. Wiping Efficiency 43

   10. Cementing Plug Drillability Test Procedure 43

   11. Bonding of Individual Plug Components (Wiper Section to Insert) 44

   12. Restriction Testing 44

   13. Wiper Deformation Caused by Preinstallation Inside a Restricted ID 45

Bibliography 46

Figures

1. Photo of 5 in. (127.0 mm) Drill Pipe Dart Installed into 3 in. (76.2 mm) ID Tube 8

2. Typical Long Fin Cementing Plug 8

3. Example of Combination Cementing Wiper Plugs 9

4. Typical Free Fitting Cementing Head 10

5. Typical Cementing Head with Manifold for Launching a Single Plug 10

6. Double and Triple Cementing Heads Designed to Launch Two or Three Full Casing ID Cementing

   Plugs Without Reloading 11

7. Top Drive Cement Head for Launching Short Fin Cementing Plugs 12

8. Top Drive Cementing Head with Integral Swivel and Internal Bypass for Launching Drill Pipe Wiper Darts and Balls 13

9. Example of a Circulating Swage 14

10. Example of a Plug Landing Seat, Baffle Collar 14

11. Photo from Large-scale Experiment Showing Damage to Wiper Plug Caused by Solids on Low Side

    of Casing 16

12. Plus Cross Section Showing Knit Lines 17

13. Loss of Bond Between Elastomer Fins and Plug Insert 18

14. Loss of Bond Between Elastomer and Insert at Interface near Diaphragm 18

15. Failure of Plug Insert During Pressure Testing 19

16. Failure of Plug Insert During Plug Bump Pressure Testing 19

17. Short Fin Bottom Plug with Hollow Core and Frangible/Rupturable Member to Allow Flow Through

    the Core 23

18. Short Fin Top Cementing Plug with Solid Core 24

19. Typical Stage Cementer 24

20. Typical Liner or Subsea Release Top Plug Assembly 26

21. ASTM Test Slabs 27

22. Samples Notched for Identification 28

23. Typical Test Setup for Bottom Plug Rupture or Flow Through Testing 30

24. Generic Bottom Plug Rupture Test Setup for Dynamic Testing 31

25. Test Apparatus That Could Be Used to Determine Pressure Required to Bypass Wiper Fins on

    Cement Plug 32

26. Typical Test Setup for Bottom Plug Flow Through and Plug Bump Pressure Testing 34

27. Sample Latch-down Seat and Latch-down Plug Prior to Latching Together 35

28. Latch-down Seat and Latch-down Plug After Seating 35

29. Latch-down Seat and Latch-down Plug Nose 36

30. Latch-down Plug Nose Being Forced Into Latch-down Seat with a Mechanical Load Frame 36

31. Latch-down Plug Nose Being Forced Out of the Latch-down Seat with a Mechanical Load Frame 36

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    Contents

    Page

32. Casing Flow Loop Apparatus 38

33. Recovered Plug Fin Section 40

34. Using an Appropriate Cutting Tool, Cut Line Down on Fin Section 40

35. Second Cut Parallel to Marked Line on Plug Fin 41

36. Full Scale Schematic of the Cross Section of the Plug Fin 41

37. Place Cut Plug Fin Section Placed over Scaled Schematic 42

Tables

1 Calculated Accumulated Volume of Wiped Fill Ahead of Top Cementing Plugs per 1000 ft (300 m) of Pipe Wiped 4

vii

Evaluation and Testing of Mechanical Cement Wiper Plugs

1. Scope

   The purpose of this technical report is for recommended testing, evaluation, and performance requirements for mechanical cement wiper plugs.

   
   

2. Normative References

   This document contains no normative references. For a listing of other articles associated with this publication, see the Bibliography.

   
   

3. Terms and Definitions

For the purposes of this document, the following terms and definitions apply.

3.1

baffle

A ring or plate made of drillable material that is mounted in the casing to provide a landing surface for a cement plug and may (or may not) also provide a sealing surface.

3.2

bump pressure

The amount of pressure applied to the casing when a cementing plug is landed (bumped) onto a baffle, float collar, or another plug.

3.3

cement (slurry)

A mixture of calcium silicates and water, possibly containing other materials, that sets to a hard, rocklike substance.

3.4

cementation/cementing

The application of pressure pumping cementing fluids (spacers and cement slurries) to various points in a wellbore.

3.5

displacement fluid

The fluid used to displace the cement slurry from the casing that is normally separated from the cement slurry by a top wiper plug and / or a spacer fluid.

3.6

drillable

Capable of being drilled up in a reasonable amount of time by a drill bit.

3.7

elastomer

An elastic, flexible rubberlike material, including natural or synthetic rubber compounds, polyurethanes, and thermoplastic elastomers.

3.8

float collar

A tool containing a one-way check valve to prevent return flow of the cementing fluids from the annulus into the casing.

NOTE It has threaded connections that attached near the bottom of a casing string and may also provide a landing and/or sealing surface for wiper plugs.

1