Early Detection and Localization of Downhole Incidents in Managed Pressure Drilling

Downhole incidents such as kick, lost circulation, pack-off, and hole cleaning issues are important contributors to downtime in drilling. In managed pressure drilling (MPD), operations margins are typically narrower, implying more frequent incidents and more severe consequences. Detection and handling of symptoms of downhole drilling contingencies at an early stage are therefore crucial for the reliability and safety of MPD operations. In this paper we describe a method for early detection and localization of such incidents, based on a fit for purpose model of the downhole pressure hydraulics, distributed pressure measurements from wired pipe, and statistical change detection methods. Using statistical change detection methods, it is possible to detect the incidents and their location at a very early stage when small changes in operating parameters are covered in measurement noise. The method has successfully been tested on experimental data from a medium-scale horizontal flow loop in Sta- vanger, Norway. The flow loop represents a 700 m borehole with emulation of the following downhole contingencies: drillstring washout, drill bit nozzle plugging, gas influx and fluid loss. In the tests, these incidents have been success- fully detected at an early stage, when detection by a human operator observing the measured data is almost impossible. The developed detection and localization method can be included as a diagnosis tool in a drilling system with MPD or conventional drilling