Preparation and Testing of Foamed Cement Formulations at Atmospheric Pressure

API RECOMMENDED PRACTICE 10B-4 SECOND EDITION, OCTOBER 2015

REAFFIRMED, AUGUST 2019

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Foreword

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• the term “shall” denotes a minimum requirement in order to conform to the recommended practice;

  
  

• the term “should” denotes a recommendation or that which is advised but not required in order to conform to the recommended practice;

  
  

• the term “may” is used to express permission or a provision that is optional; and

  
  

• the term “can” is used to express possibility or capability.

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iii

Contents

Page

1. Scope 1

2. Normative References 1

3. Terms, Definitions, and Symbols 1

   1. Terms and Definitions 1

   2. Symbols 3

4. Sampling 4

   1. General 4

   2. Method 4

5. Slurry Calculations 4

   1. Introduction 4

   2. Calculation of Base Cement Slurry Composition With and Without Surfactant(s) 4

   3. Determination of Slurry Volume and Mass 5

6. Base Cement Slurry Preparation and Testing 9

   1. General 9

   2. Conditioning Procedures 9

   3. Density Measurement 9

   4. Stability of Unfoamed Base Cement Slurry 9

   5. Determination of Rheological Properties 9

   6. Determination of Static Fluid Loss 9

   7. Determination of Thickening Time 10

   8. Determination of Compressive Strength 10

   9. Compatibility 10

7. Preparation of Foamed Cement Slurry at Atmospheric Pressure 10

   1. Unfoamed Base Cement Slurry Preparation 10

   2. Blending Apparatus 11

   3. Generation of a Foamed Cement Slurry 12

8. Atmospheric Testing of Foamed Cement Slurries 14

   1. General 14

   2. Determination of Foamed Cement Slurry Density 14

   3. Determination of Foamed Cement Slurry Stability 14

   4. Determination of Compressive Strength 19

Annex A (informative) Nitrogen Density, N2 21

Annex B (informative) Nitrogen—A Real Gas 28

Annex C (informative) Nitrogen Compressibility Factor, Z (Dimensionless) 30

Annex D (informative) Example Calculations for the Preparation of Foamed Cement Slurry at

Atmospheric Pressure 37

Bibliography 40

v

Contents

Figures

Page

1. Blending Container and Multi-blade Assembly 11

2. Example of Curing Mold for Evaluation of Foamed Cement Slurry Stability 18

3. Evaluation Report Form: Foamed Cement Slurry Stability at Temperature <90 °C (194 °F) 20

Tables

1. Nitrogen Density (kg/m3) from Temperature and Absolute Pressure in SI Units 22

2. Nitrogen Density (lbm/gal) from Temperature and Absolute Pressure in USC Units 25

1. Nitrogen Compressibility Factor from Temperature and Absolute Pressure in SI Units 31

2. Nitrogen Compressibility Factor from Temperature and Absolute Pressure in USC Units 34

vi

Preparation and Testing of Foamed Cement Formulations at Atmospheric Pressure

1. Scope

   This standard defines the test methods including the generation of unfoamed base and their corresponding foamed cement slurries at atmospheric pressure. These procedures are developed for foaming cement slurries with air, at atmospheric conditions, which could mimic a foam quality experienced with nitrogen at downhole conditions; they may be modified to accommodate other gases such as nitrogen. Slurries that are foamed with nitrogen, and their properties, will also be discussed within this standard as they are relevant to the scope of the standard.

   
   

   This standard does not address testing at pressures above atmospheric conditions, nor does this standard include or consider the effects of nitrogen solubility in the nitrogen fraction calculations.

   
   

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. However, not all documents listed may apply to your specific needs. The body of the standard should be referred to for how these documents are specifically applied. For a list of other standards associated with this standard, see the Bibliography.

   
   

   API Recommended Practice 10B-2, Recommended Practice for Testing Well Cements

   
   

   API Recommended Practice 10B-3, Recommended Practice on Testing of Deepwater Well Cement Formulations

   
   

3. Terms, Definitions, and Symbols

3.1 Terms and Definitions

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

3.1.1

additive

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

3.1.2

batch mixing

Process of mixing and holding a volume of cement slurry prior to placement in the wellbore.

3.1.3

cement

Portland cement

Material formed by the grinding of clinker, generally consisting of hydraulic calcium silicates and aluminates and usually containing one or more of the forms of calcium sulfate added during grinding.

3.1.4

compatibility

Capacity to form a fluid mixture that does not undergo undesirable chemical and/or physical reactions.

3.1.5

compressive strength

Strength of a set cement sample measured by the force required to cause it to fail in compression, expressed as force per unit area.

1