Improving Wellbore Position with High-Resolution Data

Company / Affiliation Information

• MagVAR / Surcon
• Services:
  • Magnetic Modelling
    • High accuracy local magnetic models (IFR1)
    • Real-time local magnetic observatories (IFR2)
    • High Resolution Global Magnetic Model (MVHD)
  • Survey Management
    • Real-time survey corrections
    • Survey quality monitoring
    • Fit-for-purpose uncertainty modelling

High Level View: Errors of Process

• Relate to the manner by which the survey is conducted
• Independent of sensor accuracy or performance
• Associated with known compromises in operations
• Comprise the largest “acceptable” error sources

Examples of Compromises

• BHA Design
  • Drillstring Interference, Sag
• Magnetic Reference
  • Crustal Anomalies, Solar Weather
• Survey Frequency
  • “Aliasing” in minimum curvature

Positional Error From Survey Frequency

• Wellbore trajectories assume circular arcs between stations
• Data outside of survey set can weaken this assumption
• Simple solution: More frequent surveys (<30ft)
• More often a compromise is made (95ft+)

This Problem is Not New

• High-frequency gyro surveying since the late 70s
• Continuous MWD surveying since late 80s
• Formal problem statement: Stockhausen & Lesso 2003

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Improving Wellbore Position with High-Resolution Data

Marc Willerth

 

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