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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 includes in the standard model. Error Code Description MWD MWD with Axial Interference Correction
0.004ms -2 0.004ms -2 0.004ms -2
1 2 3 4 5 6 7 8 9
ABXY-TI1 ABXY-TI2
Accelerometer bias xy – term1 Accelerometer bias xy – term2
ABZ
Accelerometer bias z-axis
ASXY-TI1 ASXY-TI2 ASXY-TI3
Accelerometer scale factor xy – term1 Accelerometer scale factor xy – term2 Accelerometer scale factor xy – term3 Accelerometer scalefactor z-axis
0.0005 0.0005 0.0005 0.0005
ASZ
MBXY-TI1 MBXY-TI2
Magnetometer bias xy – term1 Magnetometer bias xy – term2
70nT 70nT 70nT
10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
MBZ
Magnetometer bias z-axis
MSXY-TI1 MSXY-TI2 MSXY-TI3
Magnetometer scale factor xy – term1 Accelerometer scale factor xy – term2 Magnetometer scale factor xy – term3 Magnetometer scalefactor z-axis
0.0016 0.0016 0.0016 0.0016
MSZ DEC DBH
Constant declination error
0.36˚
0.36˚
Declination error dependant on the horizontal component of E h’s f ld
5000nT
5000nT
SAG
BHA Sag
0.2˚
0.2˚
AZ
Constant axial magnetic interference
0.25˚
AMID XYM1 XYM2 XYM3 XYM4
Direction dependant axial magnetic interference
0.6˚
xy misalignment 1 xy misalignment 2 xy misalignment 3 xy misalignment 4
0.06˚ 0.06˚ 0.06˚ 0.06˚
0.06˚ 0.06˚ 0.06˚ 0.06˚
0.004ms -2
ABIXY-TI1
Accelerometer bias xy – axial interference correction – term1 Accelerometer bias xy – axial interference correction – term2 Accelerometer bias z-axis when axial interference correction applied.
0.004ms -2
25
ABIXY-TI2
0.004ms -2
26
ABIZ
27
ASIXY-TI1
Accelerometer scale factor xy – axial interference correction – term1
0.0005
28
ASIXY-TI2
Accelerometer scale factor xy – axial interference correction – term2
0.0005
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