Automatic Prediction of Downhole Pressure Surges in Tripping Operations

A simplified dynamic model of the tripping operation is used together with an ensemble Kalman filter to predict transient pressure surges when running the drillstring in or out of the hole. Dynamic downhole pressure measurements from a tripping operation with mud circulation are used as input to the Kalman filter. Such data can be achieved by mud pulse telemetry at the field just before the tripping operation starts. The model is automatically adapted to the particular situation (well, bit-depths, drilling mud, etc.). This is important since exact values of some downhole parameters, like viscosity of the drilling mud, might be unknown and/or changing with time. We show by comparison with filed measurements, that the automatically updated model is capable of reproducing the transient pressure surges in consecutive runs of the string without mud circulation.