Oceaneering International Web Site - 2010

Zafiro Producer In-Field Upgrade

In September 1996, shortly after the start of production proved major upside potential at Zafiro field, Mobil Equatorial Guinea Inc. commenced a three-year program to expand production throughput aboard the FPSO Zafiro Producer and outfit the vessel for maximum ultimate oil recovery over a field production life of 15 years. Oceaneering served as the FPSO project manager for this additional Zafiro development as a member of the Mobil-led Phase 2 Project Task Force. Oceaneering's workscope covered all aspects of engineering, procurement, fabrication and equipment installation for the Phase 2 FPSO upgrade. The extensive construction program was the largest ever contemplated aboard an FPSO at an in-field location and was performed while production continued at normal targeted volumes.

Phase 2 involved the tieback of 15 additional wells to the FPSO, increasing production to 80,000 bopd from the initial 40,000, and the installation of equipment that permits long-term sustained production at that rate. Phase 2 plans called for the installation of water injection, additional power generation, and gas lift capabilities aboard the Zafiro Producer offshore at the field location. In effect, installation of this equipment more than doubled the size of the installed systems in place aboard the FPSO when it was mobilized to Zafiro. The work was performed with minimal interruption to production operations, and thus required the development and implementation of a unique program of safety and operational procedures. The total work program managed by Oceaneering extended over three West African construction seasons (1997-1999), and had an estimated value of over $230 million.

Modifications to the FPSO and installation of new equipment got underway in February 1997. A series of heavy module lifts during March 1997 installed two 60,000-bpd slug catchers, two chemical injection skids, flowline pig launchers and receivers, a well control building, a 25-ton starboard crane and extensive interconnecting piping. During the next offshore construction season, in February 1998, a total of ten heavy lifts, with weights up to 830 tons, installed a 120,000-bpd water injection system, turbine generator sets to increase power generation capacity, a shipping LACT, a Master Control Center building, two 25,000-bpd hydrocyclone water treatment systems, and a 58-man accommodations module aboard the FPSO. These lifts were made while maintaining normal production operations. Construction activity was curtailed only during oil off-loadings, when VLCC-size tankers moored in tandem to the Zafiro Producer to take on crude oil for export. Phase 2 modifications and equipment installation were completed during the 1999 construction season, with implementation of gas lift from the FPSO. The heaviest lift in the 1999 series weighed over 1,100 tons.

Even with all of the construction activity, total FPSO system uptime was maintained at over 99%, and the construction program was executed with an excellent safety record. These results confirm the effectiveness of the environmental health and safety (EHS) program and operational procedures that Mobil and Oceaneering developed and implemented for this project. The FPSO modifications constitute a construction program of unprecedented scope aboard an operating floating production system.

The fast-track project execution that resulted in first oil at Zafiro nine months after signing of the FPSO conversion contract was continued in the Phase 2 modification program. Oceaneering's flexible, responsive project management methodology, keyed to the demands of fast-track execution in general, served well for the urgent requirements of Zafiro Phase 2. The Oceaneering project team consistently met Phase 2 milestones while keeping tight control of budget objectives and maintaining quality standards. As a result of the successful fast-track execution of the Zafiro Phase 2 development, our Customer is realizing the full financial benefits of enhanced production capacity during a window of very robust oil prices.

In September 1998, with Oceaneering as the project manager, Mobil began a program of life extension repairs to the FPSO targeted at work that had been postponed for budget and schedule reasons during the initial conversion project. This program, which was ongoing through the year 2000, involves steel renewals to the FPSO's tanks and hull, and like the Phase 2 modifications, it is being performed while production continues at better than 80,000 bopd. In addition to its project management role, Oceaneering was also contracted to perform the hull repairs using techniques developed over a number of years doing similar work for the U.S. Navy.

To facilitate the life extension work, Mobil adopted a strategy proposed by Oceaneering that allows the FPSO's tanks to be emptied and gas-freed without interrupting production operations. This involves the use of a second tanker to act as a floating storage and offloading (FSO) system, receiving stabilized crude oil directly from the FPSO's process system. Oceaneering designed a separate 8-point mooring system for the FSO, which is also secured by a hawser to the bow of the FPSO. The use of an FSO permanently moored to the FPSO is but another of the unique solutions that have allowed Mobil to meet production targets at Zafiro while expanding and enhancing production capabilities and ensuring maximum ultimate recovery over the long term.