Subsea Maintenance Service Delivery:Mapping Factors Influencing Scheduled Service Duration

The oil and gas (OG) industry on the Norwegian continental shelf (NCS) leads the world in terms of the number of subsea OG installations. Ensuring the dependability of these assets is critical. Non-intrusive inspection, maintenance and repair (IMR) services are therefore needed to reduce risks. These services are planned and executed using a mono-hull offshore vessel complete with remotely operated vehicles (ROVs), a module handling system and an active heave compensated crane. Vessel time is shared between competing jobs, using a prioritized forward-looking schedule. Extension in planned job duration may have an impact on OG production, service costs and health, safety, and environmental (HSE) risks. This paper maps factors influencing the job schedule efficiency. The influence factors are identified through reviews of literature as well as interviews with experts in one of the large IMR subsea service providers active on the Norwegian Continental Shelf. The findings show that the most obvious factors are weather disruption and water depth. Other factors include job complexity, job uncertainty, IMR equipment availability, as well as the mix of job complexity.