Subsea Precommissioning Operation Completed
BJ Services Company recently completed a major subsea pipeline precommissioning operation for Saipem S.A. in Nigeria on the Akpo development, one of the largest deepwater developments ever undertaken.The Akpo field lies in the Oil Mining Lease (OML) 130 Block approximately 124 miles (200 km) south of Port Harcourt, Nigeria, with water depths of 3,936 ft to 4,593 ft (1200 m to 1400 m.)
Initially, Saipem awarded BJ Services a contract in autumn 2007 to provide subsea flooding services on the flowlines after lay. The aim of this process is to displace the raw seawater in the flowlines with filtered, treated seawater. BJ achieved this during the initial phase by running cleaning and gauging pig trains in the production and gas injection loops. Working from the Bourbon Trieste vessel, BJ used its RFM remote flooding module, which offers a number of benefits. For example, lines can be flooded without connection to a vessel, reducing vessel time and related costs, and seawater from the seabed is used, allowing for immediate hydrotesting of the lines, if required. Finally, safety is enhanced because the process is carried out without a downline and diesel-pumping spread, and impact on the environment is reduced because no byproduct from the diesel engines is released into the atmosphere. BJ Services supplied a complex series of precommissioning services on the Akpo flowlines and umbilicals, as the result of a contract awarded by Saipem in March 2008. Phase 1 involved precommissioning the gas export line, which is a 16-in. pipeline that stretches 91 miles (147 km). During Phase 2, the production, water injection, gas injection and oil offloading lines were precommissioned. The overall flowline precommissioning workscope included post-lay flooding cleaning and gauging pigging, post tie-in hydrotesting, dewatering, drying and nitrogen packing services.
The third and final phase of the precommissioning programme was carried out on the infield static and dynamic umbilicals, which range in length from three to six miles (five to 10 km). This included a full range of hydraulic and electrical testing.
Work was carried out from the deepwater support vessel Bourboun Trieste and the Akpo FPSO by BJ Services personnel with equipment from the company’s base in Port Harcourt. Over time, BJ Services has completed several successful pipeline precommissioning operations for Saipem throughout the world. In fact, the first precommissioning operation carried out by the Company upon entering the West Africa market was for Saipem S.A. in Nigeria in 1997. “We have forged an enduring and mutually beneficial working relationship with Saipem in Nigeria, and are extremely fortunate to have been given the opportunity to work on the Akpo Development,” said Lindsay Link, general manager, BJ Services, Process and Pipeline Services. “The operation was especially challenging, given the complexity of the subsea pipeline network and the deepwater environment. As the direct result of the Akpo team’s commitment and experience, and the specialist technologies used, I am pleased to report that it was carried out safely and efficiently,” he added.