Acoustic Disconnect Latest Technological Improvements for Mooring Systems

Acoustic release mooring connectors allow a drilling rig's mooring legs to be released remotely and immediately, in case of emergencies, severe weather events, or simply to save time and money during rig moves.A review of existing quick disconnect devices will be presented. The technology of quick disconnect devices is forty years old and the paper will highlight the necessary improvements that need to take place. A lighter device is needed, which would also make it faster, safer, and easier to install. The importance of overcoming battery life and signal interference issues will also be addressed as the implementation of a network relay mode and frequency hopping between several connectors can dramatically improve transmission and reception. Acoustic signal reliability can be affected by obstruction, conflicting noise from rig, or power issues from the modem. The implementation of relay mode is an important improvement in terms of acoustic signal redundancy. The relay mode function strongly improves the reliability and availability of the system. A new type of acoustically operated mooring connector has been developed, the Inter-M Release, that can release under tension loads as high as 900 tons. Videos of ABS & DNV observed tests will be shown. A tension of 900 tons is the equivalent to the breaking load of 87mm diameter grade R5 chain; yet, the Inter-M® Release is two to four times lighter and smaller than other existing quick disconnect mooring devices. It is therefore easier and safer to install, saving an average of seven hours per rig. The acoustically operated mooring connector is based on three components, all field tested and with a strong track record: The SRP Rocksteady subsea connector (DNV and ABS verified), which is the world's leading renewable connector and has been used on all major wave and tidal projects around the world Teledyne's acoustic modem, of which thousands are in use worldwide, in applications from ROVs and AUVs, as well as subsea instrumentation release systems. A needle valve from North Sea offshore industry leaders Waverley Brownall, for long term gas tight performance; integrated with an electromagnet actuator (no moving parts) for ultimate reliability. The battery life has been improved from eighteen months to five years. Acoustic relay mode and signal hopping has been implemented. Design development and component assembly details will be provided. This technology provides a significantly safer way to disconnect the rig quickly in case of emergencies (blowout, hurricanes, icebergs) and can also be used to optimize drilling efficiency by allowing faster rig moves from one location to the next.This paper will cover its potential uses including rig moving and weather avoidance; product development and qualification program; and the integration of data and communication in an ABS & DNV qualified mooring device.