Recommended Practice for Testing Well Cements

API RECOMMENDED PRACTICE 10B-2 SECOND EDITION, APRIL 2013

REAFFIRMED, APRIL 2019

Special Notes

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Copyright © 2013 American Petroleum Institute

Foreword

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Suggested revisions are invited and should be submitted to the Standards Department, API, 1220 L Street, NW, Washington, DC 20005, standards@api.org.

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Contents

Page

1. Scope 1

2. Normative References 1

3. Terms, Definitions, and Symbols 1

   1. Terms and Definitions 1

   2. Symbols 7

4. Sampling 9

   1. General 9

   2. Sampling Cement at a Field Location 9

   3. Sampling Cement Blends at a Blending Facility 9

   4. Sampling Dry Cement Additives 9

   5. Sampling Liquid Cement Additives 9

   6. Sampling Mixing Water 9

   7. Shipping and Storage 9

   8. Sample Preparation Prior to Testing 11

   9. Sample Disposal 11

5. Preparation of Slurry 11

   1. General 11

   2. Apparatus 11

   3. Procedure 13

   4. Test Fluid Conditioning 21

6. Determination of Slurry Density 22

   1. Apparatus 22

   2. Procedure 22

7. Well-simulation Compressive-strength Tests 24

   1. General 24

   2. Sampling 24

   3. Apparatus 24

   4. Procedure 25

   5. Determination of Cement Compressive Strength at the Top of a Long Cement Column 28

8. Non-destructive Sonic Determination of Compressive Strength of Cement 34

   1. General 34

   2. Apparatus 34

   3. Sampling 34

   4. Preparation of Slurry 34

   5. Procedure 34

   6. Curing Time 34

   7. Curing Schedules 34

   8. Data Reporting 35

9. Well-simulation Thickening Time Tests 35

   1. General 35

   2. Apparatus and Material 35

   3. Test Procedure 37

   4. Determination of Test Schedule 39

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      Contents

      Page

10. Static Fluid-loss Tests 48

    1. General 48

    2. Apparatus 49

    3. Safety 50

    4. Performing Static Fluid-loss Test Using Non-stirred Fluid-loss Cell 50

    5. Performing a Static Fluid-loss Test Using Stirred Fluid-loss Apparatus 54

    6. Fluid-loss Results and Reporting 57

11. Determination of Rheological Properties and Gel Strength Using a Rotational Viscometer 59

    1. General 59

    2. Apparatus 59

    3. Calibration 63

    4. Determination of Rheological Properties 63

    5. Determination of Gel Strength 65

    6. Characterization of Rheological Behavior 65

12. Well-simulation Slurry Stability Tests 66

    1. Introduction 66

    2. Slurry Mixing and Conditioning 66

    3. Free-fluid Test with Heated Static Period 66

    4. Free-fluid Test with Static Period at Ambient Temperature 70

    5. Sedimentation Test 70

13. Compatibility of Wellbore Fluids 75

    1. General 75

    2. Preparation of Test Fluids 75

    3. Rheological Properties 77

    4. Thickening Time 78

    5. Compressive Strength 78

    6. Solids Suspension and Static Gel Strength 78

    7. Spacer Surfactant Screening Test (SSST) 80

    8. Interpretation 82

14. Pozzolans 84

    1. General 84

    2. Types of Pozzolan 85

    3. Physical and Chemical Properties 85

    4. Slurry Calculations 86

    5. Bulk Volume of a Blend 88

15. Test Procedure for Arctic Cementing Slurries 88

    1. General 88

    2. Preparation of Cement Slurry 88

    3. Fluid Fraction 88

    4. Thickening Time 89

    5. Compressive Strength 89

    6. Strength After Freeze-thaw Cycling at Atmospheric Pressure 89

Contents

Page

Annex A (normative) Procedure for Preparation of Large Slurry Volumes 91

Annex B (normative) Calibration and Verification of Well Cement Testing Equipment 93

Annex C (normative) Alternative Apparatus for Well-simulation Thickening-time Tests 106

Annex D (informative) Cementing Temperatures and Schedules 109

Bibliography 111

Figures

1. Commonly Used Sampling Devices 10

2. Example of Common Mixing Device 12

3. Common Blade Assembly 12

4. Common Pressurized Fluid Density Balance 23

5. Common Pressurized Fluid Density Balance 24

6. Diagram of Mold Preparation 27

7. Typical Pressurized Consistometer 37

8. Typical Hesitation Squeeze Pressure and Temperature Schedule 46

9. Common High-temperature, High-pressure, Nonstirred Fluid-loss Cell Bodies 51

10. Common Screwed-cap Type, High-temperature, High-pressure, Double-ended Fluid-lossCell 51

11. Common Stirred Fluid-loss Apparatus 54

12. Cell and Components of Common Stirred Fluid-loss Apparatus 55

13. Typical Rotational Viscometer Schematic 60

14. Rotor and Bob Dimensions (R1-B1) 61

15. Typical Sedimentation Tube 71

16. Compatibility Testing Flowchart 76

17. Typical Conductivity Titration vs Fresh Water Spacer Volume Percent in SSST Apparatus 84

A.1 Example of a Common Cement-mixing Device for Large Volumes. 91

1. Worn Blade (right) Compared to a New One (left) 97

2. Common Calibrating Device for Pressurized Consistometer Potentiometer. 102

3. Fixture for Calibration of Upper Density Range 104

1. Alternative Consistometer Design for Well-Simulation Thickening Time, Example 1 107

2. Alternative Consistometer Design for Well-simulation Thickening Time, Example 2 108

Tables

1. Symbols 7

2. Well-simulation Test Schedules for Curing Compressive Strength Specimens (SI) 30

3. Well-simulation Test Schedules for Curing Compressive Strength Specimens (USC) 32

4. Vapor Pressure and Volume Expansion of Water at Temperatures Between 100 °C (212 °F)

   and 316 °C (600 °F) 52

5. Fluid-loss Results Reporting Form 58

6. Dimensions of Rotors and Bobs 60

7. Shear Rate for Rotor-Bob Combinations 62

8. Shear Stress per Degree of Dial Deflection 62

   Contents

   Page

9. Maximum Shear Stress for Various Configurations (300° Maximum Deflection) 62

10. Example Rheological Data Report 64

11. Optional Free Fluid and Sedimentation Results-report Form 73

12. Mixtures for Testing. 77

13. Rheological Compatibility of Mud, Cement Slurry, and Spacer 79

1. Equipment Calibration Requirements 93

2. Calibration and Verification of Well Cement Testing Equipment 94

3. Rheometer Calibration 100

4. Slurry Consistency vs Equivalent Torque (for Potentiometer with Radius of 52 mm ±1 mm) 102

1. TPBHC for Casing and Liner Well-simulation Tests 109

2. TPSP for Squeeze-cementing Well-simulation Tests 110

Introduction

Users of this standard should be aware that further or differing requirements may be needed for individual applications. This standard is not intended to inhibit a vendor from offering, or the purchaser from accepting, alternative equipment or engineering solutions for the individual application. This may be particularly applicable where there is innovative or developing technology. Where an alternative is offered, the vendor should identify any variations from this standard and provide details.

In this standard, where practical, U.S. customary units (USC) are included in brackets for information. The units do not necessarily represent a direct conversion of metric units (SI) to USC units, or USC to SI. Consideration has been given to the precision of the instrument making the measurement. For example, thermometers are typically marked in one degree increments, thus temperature values have been rounded to the nearest degree.

In this standard, calibrating an instrument refers to assuring the accuracy of the measurement. Accuracy is the degree of conformity of a measurement of a quantity to its actual or true value. Accuracy is related to precision, or reproducibility of a measurement. Precision is the degree to which further measurements or calculations will show the same or similar results. Precision is characterized in terms of the standard deviation of the measurement. The results of calculations or a measurement can be accurate, but not precise, precise but not accurate, neither and both. A result is valid if it is both accurate and precise.

Well cement classes and grades are defined in API Specification 10A.

Warning—The tests specified in this standard require the handling of hot, pressurized equipment and materials that may be hazardous and can cause injury. Do not exceed manufacturer's safety limits. Only trained personnel should perform these tests.

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Recommended Practice for Testing Well Cements

1. Scope

   
   

   This standard specifies methods and gives recommendations for the testing of cement slurries and related materials under simulated well conditions.

   
   

2. Normative References

   
   

   The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

   
   

   API Specification 10A, Specification for Cements and Materials for Well Cementing

   
   

   API Recommended Practice 13B-1, Recommended Practice for Field Testing Water-based Drilling Fluids API Recommended Practice 13B-2, Recommended Practice for Field Testing Oil-based Drilling Fluids API Recommended Practice 13J, Testing of Heavy Brines

   ASTM C109/C109M-07 1, Standard Test Method for Compressive Strength of Hydraulic Cement Mortars (Using 2 in. or [50 mm] Cube Specimens)

   
   

   ASTM C188-95, Standard Test Method for Density of Hydraulic Cement

   
   

   ASTM C618-08, Standard Specification for Coal Fly Ash and Raw or Calcined Natural Pozzolan for Use in Concrete

   
   

3. Terms, Definitions, and Symbols

3.1 Terms and Definitions

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

3.1.1

absolute density

Density of a material without the fluid around the particles, similar to the relative density and can be obtained by multiplying the relative density of a material by the density of water at 4 °C, 1000 kg/m3 (8.345 lbm/gal).

3.1.2

absolute volume

The volume occupied by a material, not including the intergranular space in the case of a solid.

3.1.3

additive

Material incorporated in a cement slurry to modify or enhance some desired property.

1 ASTM International, 100 Barr Harbor Drive, West Conshohocken, Pennsylvania 19428, www.astm.org.

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