Comparative study on two deployment methods for large subsea spools

Abstract

The demand for subsea spool deployment is increasing with the expansion of offshore projects. For a project to install multiple spools, different deployment methods can be used. The choice of method may influence the safety and the total cost of the project. Thus, it is important to evaluate different deployment methods in the planning phase. This study addresses weather window analysis of two deployment methods for large subsea spools. The purpose is to compare the efficiency of the two methods in terms of total installation time for projects with different numbers of spools. Numerical modeling and time-domain simulations of the critical activities are carried out. The simulations together with the operational criteria provide the allowable sea states, which are the key input for weather window analysis. Hindcast data from a site in the Barents Sea are used for weather window analysis. The total installation time is compared for various months, different total numbers of spools and transportation durations. The influence of the possible increase of the allowable sea states for the critical activity on the total installation time is also evaluated. Through the comparative studies, recommendations to select the proper deployment method for different situations are provided.