Offshore Triceratops Under Impact Forces in Ultra Deep Arctic Waters

Abstract

In the recent years, offshore oil drilling and production is moving towards ultra-deep Arctic region which demands an adaptable structural form. Apart from the environmental loads, offshore structures in Arctic region will also be subjected to impact forces arising due to ship platform collision. Such loads may endanger the safety of the platform due to the combined effect of reduced temperature and impact forces on the material and geometric properties of the structure. Thus, there is a need to understand the behaviour of offshore structures under impact forces in low-temperature conditions. Offshore Triceratops is one of the recent new-generation compliant platforms proved to be suitable for ultra-deepwater applications. The main aim of this study is to assess the response of triceratops under impact forces in Arctic environment numerically. As the buoyant legs of triceratops are susceptible to impact forces arising from ship platform collision, the numerical model of a buoyant leg is developed using Ansys explicit dynamics solver. The impact analyses is then carried out with rectangular box-shaped indenter representing the stem of a ship, under both ambient conditions and Arctic temperature (− 60 °C) and the local response of the platform is studied through force deformation curves and stress contours. In order to study the global response of the platform, the numerical model of triceratops is developed in Ansys Aqwa solver and analysed under the action of impact load time history obtained from explicit analysis of buoyant leg. The impact load on the buoyant leg resulted in the continuous periodic vibration of the platform. Furthermore, parametric studies were also carried out to investigate the effect of indenter velocity, size, and location on the impact response of triceratops under Arctic temperature, and the results are discussed.