Overview
- Objectives of the study:
- Quantify systematic disturbance field errors
- Propose missing coefficients needed for QC
- Analysis of global geomagnetic observatory data
- Proposed changes/additions to tool codes
- Consequences in terms of ellipses of uncertainty
Magnetospheric current systems
Ionospheric current systems
- In addition, there are induced fields:
- External magnetic fields induce electric fields in the Earth and oceans
- These generate electric currents and secondary magnetic fields
- Induced magnetic fields make up about 1/4th of the disturbance field
Motivation: Quantify systematic errors
- “During a disturbed period, the magnetic declination in the Norwegian part of the Barents Sea is often affected in such a way that the mean values of the variations from quiet level have an offset of approximately 0.5º, which may result in a significant lateral position error if not corrected.” -- SPE 166226, Edvardsen et al
Links to relevant prior work
- ISCWSA Error Models (SPE 67616, Williamson et al., 2000)
- Confidence Limits associated with Values of the Earth's Magnetic Field used for Directional Drilling (SPE/IADC 119851, Macmillan et al, 2009)
- Quantifying the uncertainty in global geomagnetic models (ISCWSA Florence, Maus et al., 2010)
- OWSG consolidated tool codes (Steve Grindrod, Son Pham, Pete Clark, Simon McCulloch and others, 2013)
....
View the entire Presentation:
Systematic and Random Contributions to the Disturbance Field (IFR 2)
Stefan Maus, Manoj Nair and Bryce Carande, MagVAR
Son Pham, ConocoPhillips
Benny Poedjono, Schlumberger