FSOU Mooring And Riser System Upgrade

Combined effort at Lufeng field brings project in ahead of schedule.

In August 2012, InterMoor and Offshore Installation Services (OIS) completed a multimillion-dollar project for Chinese installation contractor China Offshore Oil Engineering Co. Ltd (COOEC), a subsidiary of CNOOC Ltd.

The Lufeng field’s Nanhai Sheng Kai floating storage and offloading unit (FSOU) mooring and relocation project was undertaken in the South China Sea, 370 km offshore Hong Kong, over six months. This was Acteon’s first major project in China and it was completed on schedule, within budget and with no lost-time incidents.

The Nanhai Sheng Kai FSOU was moored with a single point mooring in a water depth of 142 m using a disconnectable buoy turret-mooring system. The existing mooring system at Well LF 13-1 entered service in 1992 and was operational far beyond its design life of 12 years. The system was showing signs of deterioration and corrosion.

The field operator, CNOOC, planned to extend the service life of the FSOU for another 15 years by refurbishing it and upgrading and relocating its mooring system to Well LF 13-2. This would enable production from Lufeng field to continue in a safe and reliable manner, and would also support future field development.

The project team developed detailed installation procedures before each
phase of the offshore work. The overall work scope for the project involved;

  • ƒƒthe temporary replacement of the buoy turret-mooring system at Well LF 13-1 to accommodate the Nanhai Kai Tuo FSOU and enable continuing production from the field throughout the project
  • project management, engineering, procurement and installation of a new buoy turret-mooring system for the upgraded Nanhai Sheng Kai FSOU at Well LF 13-2
  • ƒƒinstalling a new 8-in. static flow line (1687 m) and an 8-in. dynamic riser (412 m) between the buoy turret mooring system and the LF 13-2 wellhead platform.

InterMoor and OIS had just eight weeks to organise and mobilise the joint team to China so the project could start on schedule. The ability to put project management solutions in place for complex projects at very short notice is increasingly important in an industry that demands a rapid response to support global operations. The solution that InterMoor and OIS had to deliver included comprehensive in-country, on- and offshore project management for controlling the offshore installation, vessel management, procurement and fabrication activities, and all the quality, health, safety and environmental support.

Planning was complicated by the lack availability of an installation vessel in South East Asia, which meant InterMoor had to bring the Maersk Attender from the UK. In terms of project personnel, a project team was based at COOEC’s offices in Shekou, China, and a 12-man offshore team was based on the Maersk Attender and the local support vessel, the HYSY 708 multi-service vessel. Both teams had staff from OIS and InterMoor.

Meticulous planning and management were vital, as Martin Kobiela, operations director, InterMoor, explains, “Procurement of equipment for the project involved working closely with local suppliers and coordinating specialist equipment from Singapore and Europe. We selected equipment based on the expected loading and ensured that it was optimised for use with remotely operated vehicles and divers, and sized to reduce the risk of damage when pulling through mooring chain stoppers and the riser J-tube.”

In addition to the standard installation equipment, InterMoor designed custom devices to handle and protect the jacketed spiral strand wires on the winches and at the shark jaws. A dogbox was used to protect the spiral strand wire when stoppered off at the vessel’s shark jaws. A winch adapter was used to prevent overbending of the spiral strand wire at the socket when stowed on the vessel’s winch drum.

InterMoor was responsible for all of the mooring-related activities on the project, including providing a specialist engineering team and the necessary mooring expertise. OIS took responsibility for project management, including offshore management of the Maersk Attender and the HYSY708, and all riser-related activity.

Kobiela says, “Our extensive experience in providing back-of-the-boat solutions was crucial for this project. We developed procedures that enabled simultaneous operations to be performed offshore while working with divers, remotely operated vehicles and the anchorhandling vessel close to the buoy turret-mooring system.”

The InterMoor–OIS project team was assisted on the project by two sister companies: 2H Offshore, which provided riser installation engineering, and Aquatic Engineering and Construction, which supplied offshore personnel and equipment for deploying the flexible riser. Close collaboration with the customer was key to success, says Kobiela, “This was a very important project for InterMoor. We selected our team of engineers for their technical skills and on the basis of their ability to integrate with client operations and to communicate in both Chinese and English. I am convinced that this was crucial.”

Wang Jiewen, project manager and deputy manager of the engineering department at COOEC, expressed satisfaction with the project, saying, “On behalf of COOEC and our client CNOOC, we would like to thank InterMoor and OIS for their high level of performance on this project and look forward to working with them again in the People’s Republic of China in the near future.”

The successful completion of this project has led to the possibility of winning future work for the same customer. InterMoor is currently looking at similar projects scheduled for 2013 and 2014.

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