Details of changes in this revision:
- The magnitudes of the borehole misalignment terms have been increased from 0.06deg to 0.1 deg. This change was implemented because, after consideration, the group felt that the existing values were too optimistic particularly in top hole. Hence ellipse sizes can be expected to be larger in top hole.
- Replacement of the existing AMID and AMIC drillstring interference terms (which had units in degrees) with the AMIL term (which is specified in nano-Tesla). This reflects a change in how many companies do their non-mag spacing calculations. The older terms followed the philosophy in SPE67616, “A well-established industry practice is to require nonmagnetic pacing sufficient to keep the azimuth error below a fixed tolerance ~typically 0.5° at 1 s.d.! for assumed pole strengths and a given hole direction. This tolerance may need to be compromised in the least favorable hole directions.”
....
Read the Entire Report