BP's deepwater floating production facilities in the Gulf of Mexico include one tension-leg platform, three spar platforms, and one semi-submersible. In addition, two semi-submersible platforms are in the final stages of construction and commissioning. This total inventory of seven floating platforms in water depths ranging from 3000 to 7000 ft includes a wide range of riser types. In some cases the risers set industry records for design parameter combinations such as depth and diameter. They are thus of particular interest from an integrity management viewpoint.
BP is in the process of implementing a risk-based integrity management program for risers operating on these deepwater producing facilities. This paper explains the process to be applied, drawing on experience from similar processes used for pipeline systems and topside equipment. Some of the risers have instrumentation and monitoring systems which will be of value for long term integrity management, as well as day to day operations monitoring.
Examples of actions arising from an integrity management process are discussed along with challenges in implementation. The paper concludes with a summary of advantages for existing operations and the potential benefit for future riser system design arising from this program.
BP's inventory of floating production systems in the deepwater Gulf of Mexico (GoM) has grown rapidly in the past few years. The water depths in which these facilities are installed have increased, with facilities spanning depths of 3000 to 7000ft. The risers on such facilities, like the moorings, are the structural elements of the system most obviously affected by the increased water depth. The fact the risers span the entire water column also exposes them to the strong current environment of the GoM, with the potential for significant fatigue loading from loop currents and eddiesthrough phenomena such as vortex-induced-vibration (VIV).
These phenomena are taken into account by the facility designer, and large safety factors are applied. However, the technology stretch required, the uncertainty of some metocean phenomena and the resulting response of the risers have prompted the use of monitoring systems and instrumentation to be incorporated into the integrity management (IM) program.
The floating platforms include a range of riser types: toptensioned vertical risers (for production, injection, drilling or completion-workover); catenary risers (for production, injection or export); and flexible pipe risers (for production or injection). The IM process is applied to all such riser types.. While IM in its broadest application applies to all stages of design, construction, operation and decommissioning, the riser IM process described here is that being applied in the operations phase.
The BP Group IM standard applies to all wholly owned and operated BP operations, projects and assets worldwide. The purpose of the standard is to identify and manage risks that could impact the health and safety of personnel or the environment; or be a cause of facility downtime. Features of a typical IM process are shown in Figure 1.