Introduction to Wellbore Positioning Web

1

Table of Contents

Introduction to Wellbore Positioning Web

1
- Introduction to Wellbore Positioning Web — 1

Introduction to Wellbore Positioning
- Copyright notice
- Revisions
- Acknowledgements
- Sponsors
- Introduction
1.0 Coordinate Systems and Geodesy
- 1.1 The Origin – Reference Surfaces and Elevations in Mapping
- 1.2 Principles of Geodesy – The forgotten Earth science
- 1.3 Principles of Cartography – It’s a ‘Square World’! Or is it?
2. Changing from One Map System to Another
- 2.1 Ellipsoids and datums
3. True North, Grid North, Convergence Summary & Exercises
- 3.1 Map projections
- Work Examples
4. The Earth’s Magnetic Field
- 4.1 Basic Outline
- 4.2 Variations in the Earth’s Magnetic Field
- 4.3 Magnetic Observatory Distribution
- 4.4 Diurnal Variation
5. Principles of MWD and Magnetic Spacing
- 5.1 Measurement While Drilling (MWD)
- 5.1 Data Recovery
- 5.2 MWD Magnetic Spacing
6. In-Field Referencing
- 6.1 Measuring Crustal Anomalies using In-field Referencing
  - 6.1.1 IFR Survey Maps
- 6.2 Interpolated In-field Referencing
7. Survey Calculation Methods
- 7.1 Examples of current methods
8. Survey Frequency
- 8.1 Determining TVD
- 8.2 Effect of Survey Interval on Well Path Positional Uncertainty
9. Gyro Surveying
- 9.1 Background and History of Gyros
- 9.2 Oilfield Applications – A Brief History
- 9.3 Chronology of gyro development
- 9.4 Improving Performance and Service Capability
- 9.5 The Gyro Survey Process
- 9.6 ERD and Horizontal Transit
- 9.7 Ring Laser Gyro
- 9.8 Fibre Optic Gyro
- 9.9 Vibrating Structure Gyroscope
- 9.10 Coriolis Vibratory Gyros (CVG)
  - 9.10.1 Micro electro mechanical System (MEMS) – Tuning Fork Gyro
  - 9.10.2 Hemispherical Resonator Gyro (HRG)
10. Basic Gyro Theory
- 10.1 Fundamental principles
- 10.2 Gyrodata Rate Gyro
- 10.3 Earth’s rate of Rotation
- 10.4 How to Measure Azimuth
- 10.5 Sensor Errors
- 10.6 Survey Tool Calibration
- 10.7 Survey Tool Operating Modes
- 11. When to run Gyros
- 12. Correcting for Sag
13. Correcting for Magnetic Interference
- 13.1 Drilling magnetisation
14. Multi Station Analysis
- 14.1 Calculation and background
15. Correcting for Pipe and Wireline Stretch
- 15.1 Forces on the drillpipe
- 15.2 Thermal Effects
- 15a Along Hole Depth Measurements
16. Human Error v Measurement Uncertainty
- 16.1 Common Human errors
- 16.2 Misapplication of Uncertainty in Top Hole
17. Understanding Error Models
- 17.1 Error Models and Instrument Performance Models
- 17.2 Modelling Uncertainty
- 17.3 Probability in two dimensions
- 17.4 How can we determine the size and shape?
18. The ISCWSA Error Model: Introduction
- 18.1 Some background to ISCWSA
- 18.2 Covariance
  - 18.2.1 How the errors affect the observations.
- 18.3 The Variance Covariance Matrix
- 18.4 Eigen Values and Eigen Vectors
- 18.5 Collision Risk
- 18.6 Definition of Ellipse Axes
- 18.7 How errors propagate
19. The ISCWSA Error Models: Explanation and Synthesis
- 19.1 Introduction
- 19.2 Framework of the Error Model
- 19.3 MWD Error Model
- 19.4 Gyro Error Model
- 19.5 Error Model Implementation
- 19.6 Standardisation
  - 19.6.1 Why Do My Standard ISCWSA Results Not Agree with Yours?
  - 19.6.2 Non Standard Error Sources
20. Anti-collision Techniques
- 20.1 Minimum Separation Methods and Limits
- 20.2 Definition of Separation Factor
- 20.3 Separation Vector Method
- 20.4 Pedal Curve Method
- 20.5 Scalar (Expansion) Method
- 20.6 Probability of Collision
  - 20.6.1 Difference between Separation Factor and Probability Based Rules
- 20.7 Acceptable Risk of Collision
- 20.8 A simplified Calculation of Probability of Collision
- 20.9 Anti-collision Scanning and Reporting
- 20.10 The Ellipse of Uncertainty Report
- 20.11 Safe Scanning Intervals
- 20.12 Travelling Cylinder Plot
  - 20.12.1 Reading the Traveling Cylinder Plot
- 20.13 Travelling Cylinder Options
- 20.14 Using TVD “Crop” Diagrams
- 20.15 Using Ladder Plots
21. Planning for Minimum Risk
- 21.1 Designing the wellpath
22. Basic Data QC
- 22.1 Checking raw data
23. Advanced Data QC
- 23.1 Varying curvature method
24. Tortuosity
- 24.1 Illustrating tortuosity
- 24.2 Calculating Tortuosity
25. Combined Surveys
- 25.1 Combined Surveys
26. Some Guidelines for Best Practice
- 26.1 Required Data
- 26.2 Position and Referencing Data
- 26.3 The Existing Well Data Including Survey Tools and Depth Ranges
- 26.4 Existing Planned Well to be Avoided (Caging)
- 26.5 Separation Rules
27. Relief Well Drilling
- 27.1 Magnetic Ranging
28. Subsea Positioning
- 28.1 GPS Positioning
- 28.2 DGPS
- 28.3 Vessel Offsets
- 28.4 Acoustic Positioning
- 28.5 Boxing In
- 28.6 USBL
- 28.7 Section Summary
29. Wellbore survey quality control
- 29.1 Introduction
- 29.2 Standardized confidence level
- 29.3 Georeference QC tests
- 29.4 Multi-station QC tests
- 29.5 Repeated measurement QC tests
- 29.6 Independent surveys QC tests
- 29.7 Recommended Use of QC Methods
- 29.8 Concluding remarks
- 29.9 References
30. Error model validation
- 30.1 Introduction
- 30.2 Discussion relating to survey type
- 30.3 Validation through determination of individual error parameters
- 30.4 Indirect validation through the comparison of independent surveys
- 30.5 References
APPENDICES
- Appendix A: Details of the Mathematical Derivations
- Appendix B: List of MWD Model Error Sources and Weighting Functions
- Appendix C: List of Gyro Model Error Sources and Weighting Functions
- Appendix D: Some Useful Mathematics
VERSION &SUBMISSION INFORMATION

Download as PDF

10. Basic Gyro Theory

9.10.2 Hemispherical Resonator Gyro (HRG)

10.1 Fundamental principles

*The purpose of this chapter is to explain the principles of gyroscopes and how such sensors are used specifically in Gyrodata gyro survey tools to determine borehole azimuth. This section was donated to the book by John Weston of Gyrodata, but the operating principles are largely applicable to any commercial rate gyros.

Feedback

Was this helpful?

Yes No

You indicated this topic was not helpful to you ...

Could you please leave a comment telling us why? Thank you!

Thanks for your feedback.

Post your comment on this topic.

Your name *

Your e-mail address *

Comment *

Post Comment

Copyright © 2025 ISCWSA eBook — Powered by