Improved Acoustic Quick-Disconnect Technology for Mooring Operations

As the offshore oil and gas industry has changed, deep water Mobile Offshore Drilling Units (MODU) are commonly outfitted with dynamic positioning (DP) systems and on-vessel mooring equipment to facilitate drilling operations at ultra-deep and shallow water well locations. However, since many shallow water locations can experience harsh conditions and may require moorings for station-keeping performance, it is beneficial to enable a DP rig to quickly disconnect from its mooring system and avoid hazardous conditions without support vessel assistance. Providing this capability, acoustically releasable subsea mooring connectors allow a rig's mooring lines to be released remotely and almost immediately. Additionally, the ability to disconnect without Anchor Handler Vessel (AHV) assistance for mooring operations and rig transit support offers reduced risk and cost savings. A brief review of existing quick-disconnect mooring devices will be presented. It will highlight how the technology has evolved and is being used, particularly in recent years. Successes, problems, and lessons learned from past InterMoor and SRP product development will be summarized and focused attention will be given to a significant number of more recent improvements to increase the product's reliability, availability, serviceability, and robustness. Improvements to ensure reliable long-term battery life and power supply, enhance on-vessel accessibility and user-friendliness for rig personnel, and employ advanced acoustic signal transmission, reception, and device status analytics will be discussed. External modifications to reinforce its robustness during deployment and internal electromechanical changes to facilitate its serviceability will also be described. A substantially lighter and smaller acoustically releasable mooring connector was developed two years ago, tested thereafter, recently deployed on several offshore mooring campaigns, and has now been upgraded to incorporate high-fidelity electronics with the ability to release under tension loads as high as 900 tonnes. As such, this second-generation device's reliability, accessibility, and serviceability are significantly enhanced. Results from offshore deployments from recent MODU and barge mooring operations will be summarized. This technology provides a safer way to quickly disconnect mooring lines and offers cost efficiency by allowing faster rig moves from one location to the next with reduced risk. The paper will cover the work, challenges, trials, and tribulations required to bring a new product to market with cutting edge capabilities. Novel highlights will include the integration of a networked data transmission and communication system, the system's fundamental change from pneumatic to electromechanical actuation, and additional enhancements and improvements that are unique to mooring quick-disconnect devices and at the forefront of subsea technology.