New Installation Method for Subsea Pipelines in South China Sea

Abstract

The subsea pipelines between two platforms located in South China Sea were required to be replaced. In between the two platforms is a Floating Production Storage and Offloading (FPSO) unit including the mooring system, anchors and Pipeline End Termination (PLET). The new pipelines need to run below the FPSO and the mooring lines. This paper discusses a new installation method for the subsea pipelines in South China Sea. There are technical challenges to install the new 18-km pipelines in Panyu oil field. On the one hand, it needs to ensure a 500-m radius safety zone from the FPSO. The pipeline laying vessel shall not work within the safety zone due to possible interference with anchor lines. On the other hand, the new pipelines have to run below the FPSO and the mooring lines in order to avoid potential interference with existing cable and riser system. This paper considers the existing pipeline installation methods and generates a new method to install the pipelines in South China Sea. A concept of ‘dummy pipe’ is introduced to simulate the installation operation. The paper presents a series of installation sequences including assisting the pipeline laying and pulling, accurately positioning the pipelines, and protecting the existing facility. Figures are used to illustrate the installation deployment. Messenger lines were installed to run below the FPSO. The installation process was monitored. The new pipelines were installed in the field successfully. In addition, this paper further presents some recommendation for future installation practice.