| dc.description.abstract | In the oil and gas industry a new technology known as Managed Pressure Drilling (MPD)
is emerging, allowing for faster and more accurate well pressure control. MPD differs
from conventional drilling methods by closing the well using a controlled choke, often in
combination with a backpressure pump allowing for automatic pressure control. When
the drill string is extended the pipe is typically sealed of and detached from the MPD
system. This process is time consuming and limits pressure control, because the mud
flow is stopped. The Continuous Circulation System was developed to allow for better
pressure control during connections and reducing connection time. For these technologies
to become viable for use on floating rigs advanced control algorithms are necessary. To
be able to test such system simulators are necessary. In this thesis a transmission line
containing the mud column in the pipe and the annulus coupled through an elastic pipe is
presented in the frequency domain. A set of Robin boundary conditions representing CCS
is developed and coupled with a pressure node. A Ritz approximation is developed in order
to discretize the transmission line, and the Laguerre-Gram model order reduction method
is applied to obtain rational transfer function approximation. Some likely numerical issues
are discussed with this method. | |
