Extending Tieback Distances: Wet-Mate Connectors, Enabling Technologies for Critical Systems Developments
Authors: Romanisko Tom , Wright Perry 
Published: October 2008

With the economics of deepwater production driving subsea technology development, the ability to extend tieback distances is critical to the continued effort to reduce CAPEX for deepwater projects. In "mature" regions such as the GOM shelf and the UK North Sea, the tie in of remote satellite developments is already extending the life of existing platforms beyond their original decommissioning dates, yet there are many potential developments just out of reach of current tieback technology. At the leading edge of subsea production development, some operators are investigating tieback to shore with target distances of 200 km or more.

Fundamental programs in Subsea Separation, Multiphase Pumping and Subsea Electrical Power Transmission are demonstrating the critical need for high power and for high bandwidth, error free communication, where subsea processing and long step-out distances are necessary. These programs have identified wet-mateable high-voltage, power connectors and fiber-optic communication and, consequently, wet-mateable fiber-optic connectors, as critical technologies enabling the installation and hook up of the core modules for each project.

With many of these programs having reached the stage of subsea trials, or in some cases, full production installations, the wet-mate connection systems have been subjected to comprehensive "real life" production programs. The performance of these connectors, the benefits of high-voltage power systems and fiber-optic communication and the lessons learned, can significantly improve the application of these system critical technologies in future subsea production and extended tieback systems.

Introduction

The key to the use of new technologies is to start with the end in mind. It's hard to justify using more expensive systems on a straight replacement basis alone. Operators have to look at the project's total system cost over the life of field. For most subsea installation scenarios, the economics of subsea production can be improved by making use of leading edge technologies that focus on advanced facilities construction, production control and flow assurance. These technology developments are not only critical to the improved economic development of deepwater (&gt;500m) prospects where much of today's industry focus lies, but also for technical success in ultra deep waters as we pass 2000m. They are also relevant for extending the life of facilities and infrastructure in the shallow water, mature regions like the GOM shelf and the UKCS.

The implementation of new technology will only move forward if accompanied by suitable and in-depth risk assessment and risk management. Although the implementation of new technology will always carry an associated risk, the level of risk can be reduced and kept within acceptable limits through proven engineering and management practices and the application of well directed system-wide qualification test programs and detailed production trials. This approach to the implementation of new technology has been successfully proven on a number of recent high-profile developments.

The following sections will look at a variety of technologies critical to the ongoing development of the subsea oil industry and which are dependant on the use of wet-mate high-power and/or optical connectors.