Floating Production Storage and Offload (FPSO) vessels and Floating Storage and Offload (FSO) platforms are held in position by multiple mooring lines. The integrity of these lines is critical to safety and production. Breakages can result in a loss of output and may give rise to environmental issues. The long term reliability of existing contact based monitoring techniques using load cells has been questioned. Some platforms have no monitoring system fitted.
A contactless method of monitoring the integrity of mooring lines and riser dynamics, coupled with a simple deployment and recovery system, is of significant benefit to the oil and gas industry. This paper presents a novel sonar based Chain and Riser Monitoring System (CHARMS) which uses electronic scanning sonar technology to assess anchor line and riser shape thus allowing information on their motion and stress levels to be derived. CHARMS demonstrates that the use of electronic scanning is the most appropriate technology for an optimised sonar based system.
The paper will present information on the mooring lines along with the theory linking line shape to tension. The component parts of CHARMS will be discussed. It will be shown how these components are integrated to form the system and an explanation of deployment and operation will be given.