Overview:
- OWSG tool codes 1σ errors in Gtotal, Btotal Dip
- Some missing parameters: GFI, MFI, MDI
- Errors depend on the location and orientation of well
- Application 1: To analyze MWD tool performance
- Application 2: To define QC criterion
Motivation for the Study
- Operator Wellbore Survey Group (OWSG) has compiled a set of consolidated tool error models, combined effort by COP and CVX
- Tool codes specify 1-sigma error sources and their contribution to the ellipse of uncertainty of the wellbore position
- Are the MWD surveys consistent with the tool code?
- How to define whether a survey “passes QC?”
Why No Mis-alignments?
- Tool mis-alignment (XYM, SAG):
- The survey will give inclination & azimuth errors
- But these are not detectable in the QC parameters
- Sensor mis-alignment between grav and mag:
- This will result in a detectable residual in dip
- But: The ISCWSA tool codes lump these into the Magnetometer biases
- There is no direct mis-alignment term affecting the errors in the QC parameters
....
View the entire Presentation:
Field Acceptance Criteria Based on ISCWSA Tool Error Models
Stefan Maus, Ryan Croke - MagVAR, University of Colorado