Subsea wellhead and conductor systems can be subject to high fatigue damage during drilling operations, sometimes requiring to be monitored in real-time. Existing online monitoring systems use cables strapped the exterior of the riser, to display the data topside, leading to a number of potential issues.

In order to address these issues, Pulse Structural Monitoring has developed a wellhead and conductor fatigue monitoring system using acoustic data transmission. The monitoring system consists of motion sensors installed on the BOP/LMRP. Each sensor has the ability to continuously measure response without intervention for up to a 9 months. The data from each data logger is transferred in real-time to a topside processing unit via an acoustic transmitter on the LMRP.

The paper describes the requirements from Oil & Gas operators taken into account in the design followed by the different phases of testing using the Technology Readiness Level (TRL) method that the new acoustic data logger underwent including sea trial. As this type of system already exists, using cables to communicate the data topside, this new technology had to bring the advantage of not having a cable while being able to transmit and display data fast enough to be considered real-time, while maintaining a long enough battery life to last one to several campaigns. The acoustic system is proven to be able to overcome the high noise levels created during drilling operations and communicate continuously and reliably without being affected by surrounding noise or other wireless communication systems up to today's and tomorrow's deep water depth.

The paper presents a new and now proven way of monitoring wellhead fatigue in real-time and wirelessly enabling Oil & Gas operators to take informed decisions, minimising disconnect periods and collecting well integrity data, while avoiding issues related to subsea cables.

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