Technical And Economic Aspects Of The Flexible Export Pipeline System For Amoco's Liuhua 11-1 Development Offshore China

Abstract

Abstract The flexible pipe approach can provide many technical advantages and cost savings over a rigid pipe approach when considered early for a project. One such project is the Liuhua 11–1 Oil Field, located offshore China in 1000-foot water depth, which is being developed jointly by Amoco Orient Petroleum Company (AOPC), China National Offshore Oil Corporation (CNOOC), and Kerr McGee. This paper presents a comparison of technical and cost issues examined by the project team during the bid stage of the project. In addition, this paper details the technical challenges, and their solutions for the engineering, manufacturing and installation of Coflexip's flexible export pipe lines and flexible risers. Introduction Flexible pipe provides a high quality technical solution for dynamic risers and export pipelines. The Amoco Liuhua 11–1 Development Offshore China is incorporating Coflexip's flexible pipe to meet the project's technical challenges at a competitive price. The Liuhua 11–1 Oil Field is being developed using subsea technology, with a permanently moored FPS that is located over the subsea manifold and wellheads. The FPS performs drilling, completion, workover of horizontal wells, and in addition supplies the power to electric submersible pumps (ESP). The ESP pumps are used to provide sufficient down hole pressure to lift oil production from the low pressure reservoirs. Production flows directly from each well through the subsea manifold and a dual flexible export pipeline system that is connected by flexible risers directly to an FPSO. The FPSO is permanently turret moored, and the process equipment for primary and secondary separation, and water treatment is located on its deck. DESIGN PARAMETERS The following design parameters were assumed for the flowlines and risers:–Internal Fluid : Oil, Gas, & Water–Service Type : Sour–Design Temperature : 125 F–Design Pressure : 2,250 psi–Factory Test Pressure: 3,375 psi In addition, as a minimum, the following design requirements were met:–Burst Pressure : 2.25 × Design Pressure–Hydrostatic Collapse : 1.5 × Hydrostatic Pressure–Design Life - 20 Years PRE-BID BACKGROUND INFORMATION Liuhua's base case pipeline strategy was a rigid steel pipeline either fabricated onshore and towed, or laid in shallow water and towed to site. Deep-water lay was considered but rejected. All contractors interested in a deep-water lay planned to use a moored barge. The use of a moored barge increases the risk of interference since the FPS and FPSO moorings are installed prior to the pipeline installation. P. 481