Appendix B: List of MWD Model Error Sources and Weighting Functions

B1 – MWD Model Weighting Functions at Revision 3
Revisions 1 and 3 made changes to the MWD model weighting functions (see section 19.3.6 for a discussion of the revisions to the MWD model). This is the current list at revision 3. Revision 4 is a change to how certain error magnitude values are calculated and does not affect the weighting functions so this list is correct for both revisions 3 and 4. The next section lists the weighting functions which have been replaced.

B2 – Historic Terms: No Longer Used in the MWD Model After Revisions 1 and 3

See section 19.3.4 for a discussion of the revisions to the MWD model. The following weighting functions have been replaced by new methods introduced in revision 1(misalignment terms MX and MY replaced) and revision 3 (toolface dependant terms – i.e. all the remaining terms below).

B3 – MWD Defined Error Magnitudes – Revision 3
The table below defines all MWD error magnitudes at revision 3. The revision 4 changes introduce look up tables for the reference magnitude field terms DEC-G and DBH-G.Some models may also include DEC-R and DBH-R to take into account random fluctuations in the reference field. These are not explicitly included in the standard model.

B4 – MWD Defined Error Magnitudes – Revision 3
The table below defines all MWD error magnitudes at revision 3. The revision 4 changes introduce look up tables for the reference magnitude field terms DEC-G and DBH-G. Some models may also include DEC-R and DBH-R to take into account random fluctuations in the reference field. These are not explicitly included in the standard model.