A New Subsea Large Load Deployment System

Abstract

This study is part of a public-private partnership / industry sponsored project developing a detailed design of a qualified subsea 3,000+ barrel chemical storage and injection system, that requires maturing an innovative subsea facilities deployment and recovery technique for large and heavy loads. This paper describes the innovative Anchor Handling Tug Supply (AHTS) based method that was developed to provide this installation capability which is readily adaptable for accurate, safe, and cost effective subsea placement of a wide range of subsea systems and components. Design and simulation studies, supplemented with an industry Subject Matter Expert (SME) populated Qualitative Risk Assessment (QRA), have validated the features and functional performance for installing and recovering the chemical and injection facilities, which have a projected mass of around 1,000mT. The initial application is to install the 3,000 useable barrel chemical storage and injection system, after which with minor engineering and procedure updates, will be suitable for the cost effective installation and recovery of other large and heavy subsea facilities. The business driver to mature this technology is the operational cost savings that is achieved by using two anchor handling vessels of opportunity for operational support. In addition, the same installation spread is capable of recovering the installed facilities should facility repair, maintenance, or refurbishment be required. The recovery procedure is essentially the reverse of the installation operations. Thus the potential exists for this deployment technology to create an environment for game changing conditions impacting the architecture, installation, and maintenance of major subsea installations as the technology is matured and field utilized. This significant developmental project is being monitored and advised by industry representatives through the active representation of operators, service companies, and OEMs participating in the project's technical advisory committee and through the significant contribution of data and expertise.