Development, Testing and Track Record of Multi-Way Underwater Mateable Fiber- Optic Connectors for Deepwater Applications
Authors: Brown Gary , Christiansen Matt 
Published: October 2008

Subsea optical connectors enable the industry to build modular subsea components and systems utilising optical communication systems. These modular systems can thus be assembled on the seafloor, the optical connectors enabling connections and disconnections for installation and maintenance purposes or for future system expansion.

In anticipation of the future ultra deepwater applications requiring the large bandwidth, high speed and long step-out distances achievable from using optical communication systems, optical wet-mate connectors have been qualified for use to 23,000 feet (7,000m) and so far been used to over 9,900 feet (3,017m).

This paper presents an overview of the lessons learned in the design, development and testing, plus a summary of the track record, of a full range of underwater mateable fiber-optic connectors. This has enabled underwater mateable fiber-optic connectors to join the subsea industry's selection of proven components for deepwater and ultra-deepwater applications.

Subsea Optical Communication Systems

Underwater optical fiber and communication systems have been in use in the offshore and subsea oil and gas environs for many years now. The main advantages of such systems are now well known, for example:Significant increase in communication bandwidthSignificant increase in speed of data transferSignificant increase in communication distancesImmunity to electrical noisePotential cost reduction in subsea umbilical construction and installation by enabling the manufacture of smaller diameter umbilicalsWell-known temperature dependant properties of optical fiber

It is however the use of wet-mate optical connectors that has enabled modular underwater installation and this combined with the advantages above have allowed a significant growth in the following:Increasing quantity, speed and sophistication of remote, distant underwater monitoring and controlSignificantly faster underwater seismic streamer array processingNext generation subsea Christmas tree and manifold systemsSubsea separation, subsea processing and subsea production boosting systemsSignificantly longer step-out distances for remote well locations or subsea satellitesRealtime assessment of reservoir performance and optimizationRealtime health and status monitoring of subsea equipment for safety and to better understand equipment maintenance regimesGreater opportunity to access large quantities of raw subsea dataThe use of high power transmission systems which rule out conventional electrical data communications due to Electro Magnetic Interference (EMI)The opening up of long distance (200km) shore to field opportunities

It is the advent of these newer technologies moving into the subsea environs and in deeper waters that have created not only the need for optical wet-mateable connector products but also the number and increasing diversity of them as well.

The Challenge of Wet-Mate Fiber Optic Connectors

As a very brief introduction to fiber optical communications, the principle of operation exploits the ability of light to travel efficiently within a very fine glass fiber. The glass fiber is essentially an optical wave-guide in which light stays trapped within the core by near total internal reflection between the core and it's outer cladding.