Isolating Potential Flow Zones During Well Construction

API STANDARD 65—PART 2 SECOND EDITION, DECEMBER 2010

REAFFIRMED, NOVEMBER 2016

Isolating Potential Flow Zones During Well Construction

Upstream Segment

API STANDARD 65—PART 2 SECOND EDITION, DECEMBER 2010

REAFFIRMED, NOVEMBER 2016

Special Notes

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Copyright © 2010 American Petroleum Institute

Foreword

This document was prepared with input from oil and gas operators, drilling contractors, service companies, consultants and regulators. It is based mainly on experiences in the United States outer continental shelf (OCS) and deepwater operating areas of the Gulf of Mexico, but may be of utility in other offshore and land operating areas. The content of this document is not all inclusive and not intended to alleviate the need for detailed information found in textbooks, manuals, technical papers, or other documents. The formulation, adoption, and publication of API standards are not intended to inhibit anyone from using any other practices.

A future planned standard, API RP 96, Deepwater Well Design Considerations, will identify considerations for use in deepwater well design. API Std 65-2 has been written to complement the objectives of API RP 90 and API RP 96 and their recommended practices.

Shall: As used in a standard, “shall” denotes a minimum requirement in order to conform to the recommended practice.

Should: As used in a standard, “should” denotes a recommendation or that which is advised but not required in order to conform to the standard.

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This document was produced under API standardization procedures that ensure appropriate notification and participation in the developmental process and is designated as an API standard. Questions concerning the interpretation of the content of this publication or comments and questions concerning the procedures under which this publication was developed should be directed in writing to the Director of Standards, American Petroleum Institute, 1220 L Street, NW, Washington, DC 20005. Requests for permission to reproduce or translate all or any part of the material published herein should also be addressed to the director.

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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.

iii

1. Scope 1

   1. Overview 1

   2. Objectives 1

   3. Background and Technology Review 1

   4. Conditions of Applicability 1

   5. Well Planning and Drilling Plan Considerations 1

   6. Drilling the Well 2

   7. Summary of Considerations 2

2. Normative References 2

3. Definitions, and Abbreviated Terms 3

   1. Definitions 3

   2. Abbreviations 10

4. Barriers 11

   1. General 11

   2. Physical Barrier Elements 12

   3. Hydrostatic Barrier Elements 12

   4. Annular Mechanical Barrier Elements 12

   5. Mechanical Wellbore Barrier Elements 15

   6. Set Cement as a Barrier Element 16

5. Cementing Practices and Factors Affecting Cementing Success 18

   1. Introduction 18

   2. Hole Quality 18

   3. Drilling Fluid 19

   4. Casing Hardware 19

   5. Close-tolerance and Other Flow Restriction Considerations 20

   6. Engineering Design 20

   7. Slurry Design and Testing 25

   8. Wellbore preparation and conditioning 31

   9. Cement Job Execution 33

   10. Post Cementing Operations 37

6. Casing Shoe Testing 38

7. Post-cement Job Analysis and Evaluation 39

   1. Material Inventory 39

   2. Job Data 39

   3. Cement Evaluation 39

Annex A (informative) Background and Technology. 40

Annex B (informative) Well Planning and Drilling Plan Considerations 59

Annex C (informative) Drilling the Well 68

Annex D (normative) Process Summary: Isolating Potential Flow Zones During Well Construction 75

Bibliography 81

Figures

1 Sonic Strength Anomaly 17

1. Effect of Curing Pressure on Bond Failure 42

2. Annular Pressure and Temperature—Well G 55

3. Annular Pressure and Temperature—Well B 56

4. Annular Pressure and Temperature—Well A 57

5. Mud Densities Measured By Pressure Sensors in Annulus 58

B.1 Casing Shoe Depths with Pore Pressure/Fracture Gradient Graph 61

Tables

1. Most frequent Primary and Secondary Barriers that Failed in all Phases 45

2. Drilling and Service Well Control Occurrences, 1998/1999 46

3. Drilling and Service Well Control Occurrences, 2003 47

4. Surface Casing Vent Flows 47

5. Gas Migration Problems 47

6. Packer Isolation Testing and Reporting Program Results 47

7. Well Status at Time of the Incident 48

8. Blowouts by Well Type 49

9. Blowouts by Depth Category 49

10. 1991 API Survey Data on Lost Circulation 51

Isolating Potential Flow Zones During Well Construction

1. Scope

   1. Overview

      
      

      This standard contains practices for isolating potential flow zones, an integral element in maintaining well integrity. The focus of this standard is the prevention of flow through or past barriers that are installed during well construction. Barriers that seal wellbore and formation pressures or flows may include mechanical barriers such as seals, cement, or hydrostatic head, or operational barriers such as flow detection practices. Operational barriers are practices that result in activation of a physical barrier. Though physical barriers may dominate, the total system reliability of a particular design is dependent on the existence of both types of barriers.

      
      

   2. Objectives

      
      

      The objectives of this guideline are two-fold. The first is to help prevent and/or control flows just prior to, during, and after primary cementing operations to install or “set” casing and liner pipe strings in wells. Some of these flows have caused loss of well control. They threaten the safety of personnel, the environment, and the drilling rigs themselves. The second objective is to help prevent sustained casing pressure (SCP), also a serious industry problem.

      
      

      API RP 90, provides guidelines on managing annular casing pressure (ACP) including SCP, thermal casing pressure, and operator-imposed pressure. These guidelines include monitoring, diagnostic testing, establishing the maximum allowable wellhead operating pressure (MAWOP), documenting annular casing pressure, and risk assessment methodologies.

      
      

   3. Background and Technology Review

      
      

      A detailed background and technology review are in Annex A. Historical data, perspectives, studies, statistics, lessons learned, etc. are included. All this information has been written to help explain how some practices work, have become proven or invalidated, or had performance limitations placed upon their application.

      
      

   4. Conditions of Applicability

      
      

      The process of barrier element selection and installation (including cement) is governed by the anticipated presence or absence of potential flow zones that require isolation for well integrity or regulatory purposes. This document applies only when it is deemed necessary that a potential flow zone be isolated. The guidance from this document covers recommendations for pressure-containment barrier (cement, packers, etc.) design and well construction practices that affect the zonal isolation process to prevent or mitigate annular fluid flow or pressure. These practices may also help prevent loss of well control (LWC) incidents and minimize the occurrence of SCP during well construction and production.

      
      

      As presented earlier herein, the content of this document is not all inclusive and not intended to alleviate the need for detailed information found in textbooks, manuals, technical papers, or other documents. Included are those practices (well design, drilling, completion, etc.) that may positively or negatively affect pressure-containment barrier sealing performance along with methods to enhance the positive effects and to minimize any negative ones.

      
      

      This document does not address shallow water flow zones in deepwater wells which are covered in API RP 65.

      
      

   5. Well Planning and Drilling Plan Considerations

Annex B includes consideration in well planning and drilling plan determinations, such as evaluation for flow potential, site selection, shallow hazards, deeper hazard contingency planning, well control planning for fluid influxes, planning