The current trend for the offshore industry to move into greater water depths has led to increasing challenges for deepwater mooring systems. These systems are now seen by operators as a major technical constraint on the cost effective development of deepwater fields.
The petroleum industry now is highly focused on the need for technical development in this area. The primary concern has been to develop reliable and high strength moorings for FPSOs in the rapidly growing deepwater development market. Key functional requirements for new mooring systems can be categorized as follows (in order of priority):
- Reliability (particularly for production applications)
- High lateral and vertical load capability (performance)
- Low "all-in" installation costs
- Suitability for a wide range of soil conditions
- Minimized project lead times.
The drilled pile anchoring system, developed by Balmoral Trident Projects, is a different concept for the installation of moorings for permanent or temporary floating structures and vessels. It has specific advantages for the installation of deepwater mooring systems employing catenary or taut leg mooring systems, and has other potential uses such as shallow water permanent moorings or tanker moorings for extended well tests.
Low cost tubulars
The system uses low cost tubular components and adapted drilling technology to allow cost effective deployment of a secure mooring termination point in shallow or deepwater. The system is tolerant of soil conditions and does not require alignment, thus reducing survey costs during the planning and installation phases.
The drilled pile anchor has been designed so that it can be deployed from a conventional drilling rig, using standard drilling techniques or deployed by a suitably equipped construction type vessel.
The drilled pile anchor can be installed in a single continuous operation, does not require a hole to be pre-drilled, and does not require removal from the hole and reinsertion at any stage of the installation operation. The mooring line connection point is mounted on the pile casing, such that the pile does not need to be specifically oriented with regard to the direction of the mooring line during deployment. The pile will be installed with the mooring line (or the mooring line terminal components) pre-connected.
The potential applications of the drilled pile mooring are broad in scope and the system is designed to provide a cost effective alternative to existing anchoring systems. In general, the drilled pile concept provides significant cost benefits when compared to conventional mooring technologies in deepwater locations.
In particular, when comparisons are made with conventional driven (or drilled and grouted) piles and suction anchors, the costs related to engineering design and construction will be considerably reduced.
