簡介：BJ公司最近在尼日利亞完成一項重要海底管線工程的部署工作，該項目是Saipem 在尼日利亞的一個超深水Akpo項目。
BJ Services Company recently completed a major subsea pipeline precommissioning operation for Saipem offshore Nigeria on the Akpo development, one of the largest deepwater developments ever undertaken.
Akpo is a gas and condensate field in the Oil Mining Lease 130 Block, approximately 124 miles (200 km) south of Port Harcourt, Nigeria, and operated by Total Upstream Nigeria, a Total subsidiary, on behalf of license partners CNOOC, Petrobras, and Sapetro. Akpo has proved and probable reserves estimated at 620 million bbl of condensate and greater than 1 Tcf of gas, and is being developed through 44 subsea wells tied back to the Akpo Floating Production Storage and Offloading (FPSO) vessel, which accepts the condensate. The gas is piped 150 km to the Amenam/Kpono platforms, from where it will be sent to the Bonny liquefaction plant.
The Akpo FPSO.
The wells are placed at water depths between 3,936 ft and 4,593 ft (1200 m to 1400 m). At these depths, flooding and testing a pipeline with a conventional vessel-based pumping spread becomes quite challenging and costly, as the large pressure drop down the long pipeline necessitates an increase in diameter.
To circumvent these challenges, Saipem awarded BJ Services a contract in March 2008 to supply a complex series of precommissioning services on the Akpo flowlines and umbilicals in three main phases:
Phase 1 involved precommissioning the gas export line, which is a 16-in. pipeline that stretches 91 miles (147 km)
In 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
Phase 3 involved precommissioning of the infield static and dynamic umbilicals, which range in length from 3 to 6 miles (5 to 10 km). This included a full range of hydraulic and electrical testing
BJ Services' RFM, ready for deployment.
For this scope of work, BJ Services employed its Remote Flooding Module (RFM), which allows lines to be flooded with treated, filtered seawater without connection to a vessel. The unit, which includes the required filtration and chemical-injection systems, uses the hydrostatic head available outside the empty pipeline to flood the line with seawater. Once the hydrostatic head is equalized, a boost pump powered by a remotely operated vehicle (ROV) is used to propel a pig through the line to a receiver. If required, an ROV-powered subsea hydrotest pump can be used to hydrotest the pipeline subsea.
All of these benefits serve to reduce vessel time and related costs. In addition, 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.
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.
This project is the latest in a long series of pipeline precommissioning operations that BJ Services has performed for Saipem throughout the world, the first of which was carried out in another Nigeria project 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.
For more information visit the company’s web site at
www.bjservices.com .
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