Modeling Large Equipment Behavior in the Sea Splash-Zone Using Methods of Computational Fluid Dynamics

Abstract

Oil industry uses a complex device, called the "Christmas tree" (XT in the remainder of the thesis) to control the hydrocarbon flow out of the oil well and for various other purposes. In case of off-shore extraction, the device has to be submerged into the water and then delivered further down. The most dangerous part of the delivery process is known to be the splash-zone of the sea. In order to effectively simulate the XT's behaviour during delivery, a geometrically simplified model of the latter has to be created. Yet this model should posses the hydrodynamical properties of a real XT. In the first part of this thesis, a computational fluid dynamics (CFD) simulation is performed to investigate the results of a previous experimental work conducted on some proposed XT models. Significant disagreement between experimental results and the results of CFD modelling has been observed. Possible explanations of this divergence are given. In the second part of this work the methodology of modelling the XT's behaviour in the splash-zone using CFD is developed. The built model allows to simulate different weather conditions and evaluate the forces acting on the XT. The necessity of including fluid-structure interaction (FSI) into the model is investigated by comparing results obtained with and without FSI respectively.