Installation of Mooring and Riser Systems for Floating Production Vessels
Authors: Wilkinson C. , Cook P. , Frazer I. , Mackinnon J. , Johns J. , Bowie M.M. 
Published: October 2008

This paper presents an overview of the operations involved in the installation of mooring and riser systems for floating production vessels, as a result of the experience SCS have gained on the installation of several systems in various parts of he world. The moorings and risers installation phase forms a critical part of the overall field development. This is especially true for marginal field developments whereby problems with installation activities can affect the field startup date. Similarly in deepwater fields, problems with installation can result in complex and time-consuming intervention works. The principles of the installation, construction vessels required to perform the work and an overview of the marine operations will be presented along with the engineering developments, which are a direct result of the projects performed. Installation considerations associated with the various components of the systems and their criticality to the overall operation require necessary variations for different mooring configurations and riser layouts. This along with the sensitivity to weather conditions has been investigated. The paper will also address the evolution of installation techniques for deep water field developments where the associated engineering challenges not only act as a catalyst for new equipment and procedures but highlight environmental effects which should be considered during the design phase.

Introduction

The use of FPSO's is proving to be a very cost-effective means of developing small marginal fields in various parts of the world. In most cases the hydrocarbons are extracted through a series of subsea wells which are linked back to a floating production unit through a system of flowlines and dynamic flexible risers. The produced fluids are then processed onboard the vessel where the oil is stabilized and stored in cargo tanks for off loading to a shuttle tanker and the gas is either reinjected into a suitable formation or transported through a flowline to a main gas export trunkline. The ability of the PSO to store crude oil and transfer to a shuttle tanker is very suited to remote field developments where there is no existing pipeline infrastructure.

The installation of the FPSO and associated hardware is a critical element in the success of the overall field development project. This paper describes the procedures and equipment involved in the installation of a typical FPSO including :-anchors and mooring systemflexible riserstowing of the FPSO to locationmooring and riser hook up The information presented in this paper is generic in nature, however it is based upon a number of FPSO installation projects for which Stolt Comex Seaway have been responsible for both in the North Sea and elsewhere in the world.

The requirement to develop oil and gas reserves in the deepwaters off the continental shelf has increased in recent years, resulting in an increasing interest in deep water locations for FPSO's. The issues associated with the installation of FPSO's in deep water are also addressed within this paper.