ABSTRACT
In harsh operational conditions environmental factors can affect the performance of DP which can lead to loss of the position control ability. For a Mobile Offshore Drilling Unit (MODU), loss of position without safe disconnection could result in critical damage not only to the well, but also to the subsea equipment. For an Offshore Support Vessel (OSV), loss of position could lead to collision with the nearby installation during operation or to damage to the subsea facilities. In order to increase the safety and reliability of a DP system, it is important to identify and quantify all influence factors and the way that they can affect the DP performance. For example “bad weather condition” is an effective factor on the position reference sensor or the local position reference system. Such operational conditions can vary from place to place and may have a dynamic nature in a specific location. Moreover, it is important to investigate safe recovery back to position, safe disconnection and reconnection when the loss of position is outside the safe operational range.
