A dynamic model for drain back to active mud pit combined with a well model during drilling

There are no published mathematical models that combine the dynamics of the returned fluid flow to the active mud pit (top side drilling) and the dynamics of the bottom side of the well being drilled. In this paper a simple dynamic model that combines the top and the bottom side drilling operations is provided. The model has been simulated for various operational scenarios during drilling including pipe connection, movements of drill string and reservoir influx. This combined model can be used for studying not only the pressure dynamics but also to estimate the return fluid flow rate and hence to detect kicks and losses occurring in the well.