New Approach Objectives:
- Avoid Orthogonality Issues
- Allow for more sensors to be used
- Make Calibrations more accurate
- Speed up Calibration Process
- Improve MWD Accuracy
New Approach
- For Example: T W
- X is 0 90
- Y is 90 90
- Z is 0 0
- Microtesla 4AM :T W
- A is -30 25
- B is 30 90
- C is -90 90
- D is 110 150
- Find the 2 alignments for each sensor
- Alignment from along hole axis W
- Alignment from high side axis T
- Include all sensors available in the tool
- Calibrate each sensor’s 2 alignments v Temperature using a ‘hot’ tumble and a ‘cold’ tumble (Use a linear interpolation for W and T at other temperatures)
- Using actual alignments corrected at each temperature
- Set tool to inc 60, azi 0, Tf -45, heat to 150 and record while cooling
- Set tool to inc 120, azi 180, Tf 135, heat to 150 and record while cooling
- Determine least squares best fit polynomials to correct for scale and bias
- In Instrument firmware use temperature corrected sensor data and actual alignments to produce synthetic 3 axis perfectly orthogonal data for surveys
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Angus Jamieson