Next Generation 3D Dropped Object Risk Assessment

Abstract

Abstract Offshore operations are continuously heading towards deeper, harsher and more complex environment. As offshore infrastructure is increasingly being transferred to the seabed, it has become more critical to analyze dropped object risks accurately. Traditionally, a two dimensional approach is used to estimate the risk of dropped objects. This method tends to involve the representation of subsea structures as simple geometrical shapes on a flat elevation. Coupled with selectively defining drop points based on engineering judgment, the risk picture of a hit on the structure from sinking objects is both limited and undervalued due to the limitations of this methodology. Selection and positioning of risers that extend deep into the ocean depths are plagued not only by its unique environmental conditions but also from the nature of its operation and connection points. The screening process involves risers with different profiles and properties, thus dissimilar exposures to dropped objects. This aspect is often overlooked due to the lack of visibility and may adversely impact facility design and resulting operational procedures. This paper demonstrates the importance of applying innovation and taking advantage of technology to continually add value through enhancing safety with cost effective methods to drive more informed decisions for dropped object risk assessments. Lloyd's Register has packaged its years of experience in this domain into its new software to calculate the risk of exposure and damage to subsea structures such as hydrocarbon risers, umbilicals, mooring lines, subsea valves, templates and more. This methodology is compliant with existing industry practice and is further improved with intuitive visualization and a more comprehensive analysis of the dropped object risk. This new tool utilizes a continuous distribution of drop points defined by, but not limited to, topside crane specifications and their operating profiles. The impact of directional and magnitude of ocean currents on both floating and sinking objects are considered across the entire column. Automation of this task has led to new frontiers in performing parametric studies helping clients identify the risk drivers in the overall picture by introducing site-specific safety improvements for crane operations in the form of easy-to-use visual aids, optimized supply vessel approaches to offshore facility and optimization of subsea infrastructure layouts. These results are presented intuitively through the use of three dimensional plots, polar charts and more.