Optimization of well Start – up (#2)
Location: Norway / Austria | Client: University of Leoben | Published: Tue, 04/24/2012
Technical Solution in Pipe-It
The difficult task when simulating well start-up is that two different environments have to be covered: reservoir (porous media) and pipe (tubing). Because there is no software that is able to handle the simulation of flow through porous media and also in pipe is it necessary to develop a coupled model to combine a reservoir simulator with a pipe flow simulator.
The software that used for this thesis is the reservoir simulator SENSOR 6k, the pipe flow simulator OLGA 6 GUI and Pipe-It to couple the two simulators.
In well start-up operations the only parameter that can be influenced directly is the change in choke position and the corresponding change in THP. This change is introduced in the OLGA model. OLGA then calculates how this change affects the inflow pressure into the tubing at bottom of the well. From this point on the SENSOR model calculates the caused changes in flow rates within the reservoir. The communication of the two models is handled in Pipe-It. The entire simulation is broken down into small time steps (TSs), eg. 15 seconds. For each TS Pipe-It with the help of OLGA and SENSOR optimizes the change in THP. Optimizing means to ensure the largest increase in surface flow-rate for each TS but without violating maximum change in pressure and/or flow rates.
Besides simulating well start-up this paper also shows an efficient way to simulate shut-in conditions within the coupled model. This is important because the initial state of a well before start-up is shut-in.