Application of ROV in OBN Subsea Deployment

At present, the deployments of Ocean Bottom Nodes (OBN) are usually carried out by two methods, lowering down from the vessel deck directly with connected securing cables, or deployment subsea via ROV. The method of lowering OBNs down from vessel deck directly is used in areas with water depth less than 100 m, low current conditions and flat seabed terrain. The ROV deployment method will be used in areas with water depth more than 100 m. It can be deployed in higher velocity current conditions and on complex underwater terrain environments. The number of OBNs carried by ROV is normally limited to each ROV launch, which will greatly limit the efficiency of any accurate OBN deployment by ROV. This paper introduces a bespoke ROV-friendly OBN launch and recovery system (LARS). Based on an ROV-friendly design concept, a large number of OBNs can be safely and quickly taken out from the launch and recovery system and deployed by the ROV in quick successions. This achieved continuous and uninterrupted subsea deployment, avoiding time delays which would have been caused by the frequent launch and recovery of the ROV system. The efficiency of accurate OBN deployment by ROV was thereby greatly improved.