Early Pack-Off Diagnosis in Drilling Using an Adaptive Observer and Statistical Change Detection. Issue 6 (2015)

• Record Type: Journal Article
• Authors: Willersrud, Anders; Imsland, Lars; Blanke, Mogens
• Is Part Of: IFAC-PapersOnLine. Volume 48:Issue 6(2015)
• Page Start: 177
• Page End: 182
• Publication Date: 2015
• Subjects: Fault diagnosis -- adaptive observer -- multivariate statistical change detection -- oil and gas drilling -- pack-off; Automatic control -- Periodicals; 629.805
• DOI: 10.1016/j.ifacol.2015.08.028
• Languages: English
• ISSNs: 2405-8963

Abstract

Abstract: 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.