Early pack-off diagnosis in drilling using an adaptive observer and statistical change detection

Anders Willersrud, Lars Imsland, Mogens Blanke

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Pack-off is a partially or complete blocking of the circulation flow in oil and gas drilling, which can lead to costly delays. Early detection and localization of a pack-off is crucial in order to take necessary actions avoiding downtime. This incident will affect physical friction parameters in the well. A model-based adaptive observer is used to estimate these friction parameters as well as flow rates. Detecting changes to these estimates can then be used for pack-off diagnosis, which due to measurement noise is done using statistical change detection. Isolation of incident type and location is done using a multivariate generalized likelihood ratio test, determining the change direction of the estimated mean values. The method is tested on simulated data from the commercial high-fidelity multi-phase simulator OLGA, where three different pack-offs at different locations and with different magnitudes are successfully detected at an early stage and with low false alarms
Original languageEnglish
Issue number6
Pages (from-to)177–182
Publication statusPublished - 2015
Event2nd IFAC Workshop on Automatic Control in Offshore Oil and Gas Production - Florianópolis, Brazil
Duration: 27 May 201529 May 2015


Conference2nd IFAC Workshop on Automatic Control in Offshore Oil and Gas Production


  • Fault diagnosis
  • Adaptive observer
  • Multivariate statistical change detection
  • Oil and gas drilling
  • Pack-off

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