| dc.description.abstract | When drilling from a floating rig the ocean waves induces a vertical motion on the rig. This movement is called heave motion. During a connection, when the drill string is extended, the drill string is attached to the rig and follows the movement of the rig. This causes the drill string to act as a stamp down in the well which causes pressure fluctuations down in the well. These fluctuations can in worst case have disastrous consequences. To prevent this the fluctuations in down-hole pressure should be controlled. Several MPD techniques with a topside valve for controlling the pressure have been tested. This has shown not to be effective enough due to the time delay when predicting the movement of the waves.
A valve that is placed down-hole is therefore developed, and given the name HeaveLock. The placement of the valve makes the prediction of the wave movement unnecessarily.
A laboratory facility has been made at NTNU to model the connection scenario. Because of the high cost of using a lab, a simulator has been made to replicate the lab.
The purpose of this thesis is to make the simulator as similar to the lab as possible. This is done by identifying dynamics in the laboratory, including the friction characteristics and valve characteristics. Experiments have been conducted in the lab and compared to the same experiments done in the simulator. The comparison has shown that the simulator and lab has almost identical behavior. Though the linear feedforward controller has not shown the same success in the lab as in the simulator.
A laboratory facility has been made at NTNU to model the connection scenario. Because of
the high cost of using a lab, a simulator has been made to replicate the lab.
The purpose of this thesis is to make the simulator as similar to the lab as possible. This is done by identifying dynamics in the laboratory, including the friction characteristics and valve characteristics. Experiments have been conducted in the lab and compared to the same experiments done in the simulator. The comparison has shown that the simulator and lab has almost identical behavior, apart from the attenuation of the fluctuations. | en |
