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 Ap1.3.6 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. Error Code Description Propagation Mode Weighting Function MD Inc Azimuth 1 ABXY-TI1 Accelerometer bias – term1 S/R 0 - cos𝐼 𝐺 𝑡𝑎𝑛𝜃. 𝑐𝑜𝑠𝐼. 𝑠𝑖𝑛𝐴 𝑚 𝐺 2 ABXY-TI2 Accelerometer bias – term2 S/R 0 0 𝑐𝑜𝑡 𝐼 − 𝑡𝑎𝑛𝜃. 𝑐𝑜𝑠𝐴 𝑚 𝐺 3 ABZ Accelerometer bias z-axis S 0 −𝑠𝑖𝑛𝐼 𝐺 𝑡𝑎𝑛𝛩. 𝑠𝑖𝑛𝐼. 𝑠𝑖𝑛𝐴 𝑚 𝐺 4 ASXY-TI1 Accelerometer scale factor – term1 S 0 𝑠𝑖𝑛𝐼. 𝑐𝑜𝑠𝐼 √2 − 𝑡𝑎𝑛𝜃 . 𝑠𝑖𝑛𝐼. 𝑐𝑜𝑠 𝐼 . 𝑠𝑖𝑛𝐴 𝑚 √2 5 ASXY-TI2 Accelerometer scale factor – term2 S/R 0 𝑠𝑖𝑛𝐼. 𝑐𝑜𝑠𝐼 √2 − 𝑡𝑎𝑛𝜃 . 𝑠𝑖𝑛𝐼. 𝑐𝑜𝑠 𝐼 . 𝑠𝑖𝑛𝐴 𝑚 2 6 ASXY-TI3 Accelerometer scale factor – term3 S/R 0 0 𝑡𝑎𝑛𝜃. 𝑠𝑖𝑛𝐼. 𝑐𝑜𝑠𝐴 𝑚 −𝑐𝑜𝑠𝐼 2 7 ASZ Accelerometer scalefactor z-axis S 0 −𝑠𝑖𝑛𝐼. 𝑐𝑜𝑠𝐼 𝑡𝑎𝑛𝛩. 𝑠𝑖𝑛𝐼. 𝑐𝑜𝑠𝐼. 𝑠𝑖𝑛𝐴 𝑚 8 MBXY-TI1 Magnetometer bias – term1 S/R 0 0 − 𝑐𝑜𝑠 𝐼 . 𝑠𝑖𝑛𝐴 𝑚 𝐵. 𝑐𝑜𝑠𝜃 9 MBXY-TI2 Magnetometer bias – term2 S/R 0 0 𝑐𝑜𝑠𝐴 𝑚 𝐵. 𝑐𝑜𝑠𝜃 10 MBZ Magnetometer bias z-axis S 0 0 −𝑠𝑖𝑛𝐼. 𝑠𝑖𝑛𝐴 𝑚 𝐵. 𝑐𝑜𝑠𝛩 11 MSXY-TI1 Magnetometer scale factor – term1 S 0 0 𝑠𝑖𝑛𝐼. 𝑠𝑖𝑛𝐴 𝑚 . (𝑡𝑎𝑛𝜃. 𝑐𝑜𝑠𝐼 + 𝑠𝑖𝑛𝐼. 𝑐𝑜𝑠𝐴 𝑚 ) √2 12 MSXY-TI2 Accelerometer scale factor – term2 S/R 0 0 𝑠𝑖𝑛𝐴 𝑚 . (𝑡𝑎𝑛𝜃. 𝑠𝑖𝑛𝐼. 𝑐𝑜𝑠𝐼 − 𝑐𝑜𝑠 2 𝐼. 𝑐𝑜𝑠𝐴 𝑚 − 𝑐𝑜𝑠𝐴 𝑚 ) 2 13 MSXY-TI3 Magnetometer scale factor – term3 S/R 0 0 (𝑐𝑜𝑠𝐼. 𝑐𝑜𝑠 2 𝐴 𝑚 − 𝑐𝑜𝑠𝐼. 𝑠𝑖𝑛 2 𝐴 𝑚 − 𝑡𝑎𝑛𝜃. 𝑠𝑖𝑛𝐼. 𝑐𝑜𝑠𝐴 𝑚 ) 2 14 MSZ Magnetometer scalefactor z-axis S 0 0 −(𝑠𝑖𝑛𝐼. 𝑐𝑜𝑠𝐴 𝑚 + 𝑡𝑎𝑛𝛩.𝑐𝑜𝑠𝐼).𝑠𝑖𝑛𝐼.𝑠𝑖𝑛𝐴 𝑚 15 DEC Constant declination error G 0 0 1 16 DBH Declination error dependant on the horizontal compon n of E h’s f ld G 0 0 1 𝐵. 𝑐𝑜𝑠𝛩 17 SAG BHA Sag S 0 𝑠𝑖𝑛 𝐼 0 18 AMIC Constant axial magnetic interference S 0 0 1
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