Optimizing Subsea Umbilical Installation Through Engineered Loop: A Practical Approach

Abstract Subsea umbilicals are commonly used to connect offshore facilities or subsea equipment for transferring fluid, electrical power, and communications. It is standard practice to order additional length to account for subsea conditions and installation challenges. After installation, excess length is managed through trimming, termination with the head refitted, or spooling onto a reel. Provision of an engineered loop in the routing is an alternative to managing the excess length without compromising the structural integrity, as it does not require trimming or installation of additional components. To design an engineered loop, several factors need to be considered, i.e., shallow/deep water, seabed roughness, neighboring assets, crossings, dominant wave and current direction, and soil condition. The behavior of the engineered loop shall be studied using FE software "OrcaFlex". OrcaFlex uses structural parameters such as diameter, bending stiffness, axial stiffness, etc., along with its weight to model the actual behavior of the umbilical under the influence of the environmental loading. Dynamic analysis for a 3-hour storm shall be performed to evaluate the long-term stability of the loop. The engineered loop profile was modeled to propose the configuration, and the results highlight an effective measure for controlling its movement and structural integrity, specifically MBR, maximum tension, and maximum displacement. Iterative simulations were conducted on multiple wave-current loading directions. Long term stability of the loop was also evaluated to determine whether secondary stabilization is required for the case in point. The results verify that the MBR, maximum tension, and maximum displacement of the umbilical in the loop area are under the acceptable criteria. The engineered loop will retain its shape with the support of secondary stabilization to control its movement. Furthermore, there is no kinking or sharp twist on the umbilical within the loop geometry. Results indicate that the loop configuration will be undisturbed, and hence the umbilical integrity is ensured. It is concluded that the umbilical engineered loop is a highly effective solution to address this installation challenge. The proposed engineered loop solution improved on the conventional means, i.e., umbilical trimming, termination with head refitted, or spooling onto a reel, to handle the excess length. The applicability of conventional approaches is limited by the umbilical structural integrity, offshore workmanship, and lower installation productivity. Whereas an engineered loop is highly effective at addressing the installation challenge of excess umbilical length without being limited by the downsides of the conventional approaches.