Overview:
- Motivation IFR2 uncertainties – how far is the “cut-off” distance from observatory to drill site?
- Geomagnetic reference
- Data - selection and processing
- magnetic observatories/permanent variometers
- focus (initially) on higher geomagnetic latitudes
- we want robust statistics – so need a lot of data
- Results - including seasonal and solar cycle variations
Motivation:
- To improve geomagnetic referencing for MWD (IFR2)
- Provide a more robust answer to the questions:
- How far away can an observatory be from the drill site and still be useful for IFR2?
- What is the uncertainty in the estimates of the external field (IFR2)?
- Provide information to industry on the effectiveness and convenience of making use of existing long-running magnetic observatories
- Provide information to observatory operators worldwide on the worth (and potential source of funding) of their data
Geomagnetic Reference for MWD
- Core (or main) field
- Standard MWD
- + Local crustal field
- MWD+IFR1
- External field
- MWD+IFR2
Including more sources of the Earth’s magnetic field
- Reduction in uncertainty
....
View the entire Presentation:
External Field Variations and Critical Observatory Distance (COD)
Ellen Clarke, Laurence Billingham and Ciarán Beggan