Tool Performance Verification
- The uncertainty in the wellbore position is computed from tool error models
- These uncertainties are only valid if tool performance meets the assumptions of the tool error model
- This has to be verified by Quality Control
- The QC criteria need to be computed from the tool error model
References to Prior Work
- SPE 103734 and SPE 105558 (2006), R. Ekseth, K. Kovalenko, J. Weston, T. Torkildsen, E. Nyrnes, A. Brooks, and H. Wilson) describes how to verify that the various error sources are within the assumptions of the tool code. Also contains the relevant weighting functions to compute QC thresholds from tool code.
- ISCWSA 39, Long Beach, (2014), S. Maus & R. Croke - Field Acceptance Criteria Based on ISCWSA Tool Error Models explains dynamic QC parameters
- ISCWSA 40, Long Beach, (2014), S. Maus, M. Nair, B. Carande, S. Pham & B. Poedjono - Systematic and Random Contributions to the Disturbance Field (IFR2) provides values for the magnetic disturbance field error model coefficients that were included in OWSG Rev-2.
- SPE 178843 (2016), S. Grindrod, P. Clark, J. Lightfoot, N. Bergstrom & L. Grant – Reference paper describing the OWSG Standard Survey Tool Error Model
Objectives
- Provide a simple criterion that indicates whether a
survey passes or fails QC for an OWSG tool code - Enable production of QC plots which are intuitive
and convey all needed information, then - Provide a web API to enable both of these functions
What Does the MWD Tool Measure?
- Measure 6 quantities, get 6 parameters:
- Inclination, Magnetic Azimuth, Tool Face (use for steering!)
- Gtotal, Btotal, Dip (use for QC!)
What do we need in order to QC a survey?
- Reference values (Gtotal, Btotal, Dip)
- Uncertainties (1 sigma) of all the error sources
- An actual downhole measurement that we want to Quality Control
- A QC algorithm or application that determines whether a survey passes or fails
...
View the entire Presentation:
A Public Web API to Provide Dynamic Quality Control for the ISCWSA Error Models
Stefan Maus, PhD: Founder and CEO, MagVAR