The Development and Application Of HT/HP Fiber-Optic Connectors For Use On Subsea Intelligent Wells
Authors: Wright Perry , Barlow Stewart , Brees Anton 
Published: October 2008

One of the most important areas of Offshore Oil and Gas R&D in recent years has been the ongoing development of improved reservoir and production monitoring technology. Nothing else offers the potential returns that come with increased understanding of the reservoir, and the improvements in realtime production control that this knowledge can provide.

For the past three years Ocean Design, Inc. (ODI), working with the Intelligent Wells Group at BP America Production Company in Houston, have been developing a revolutionary small form-factor, wet-mateable, fiber-optic connector designed for subsea x-tree and down-hole applications. From initial conception this has been a challenging development, given the harsh environments encountered down-hole and at the tree-tubing hanger interface, and the small space envelope available through any Vertical or Horizontal x-tree system. Ocean Design is working closely with BP and FMC on a first system to mount to the FMC Horizontal tree specified by BP for the upcoming Atlantis project in the deepwater GOM.

Building on Ocean Design's six years of experience with wet-mate fiber-optic and hybrid connectors, the I-CONN connector is a critical link in the development of fiber-optic based point source and distributed intelligent well sensor systems that are essential to improved real-time production control. This paper provides a brief overview of fiber-optic systems proposed for use in intelligent wells, reports on the development and application of the HT/HP connector, and discusses the optical and mechanical performance and qualification requirements needed for this application. It is intended to present a second paper covering the qualification and first installations at OTC 2004.

Introduction

With forecasts of ever dwindling reserves, any technology that can offer a significant improvement in recoverable reserves has to be given serious consideration. The continuing development of Intelligent Well Monitoring technology and the near future step to Intelligent Well Control is showing excellent potential to facilitate this increase in recoverable hydrocarbons, with early forecasts of 5% to 15% being voiced.

One of the primary techniques for the implementation of intelligent wells technology is the use of optical fiber sensors providing high-quality data on down-hole conditions continuously and in real-time with high pressure and high temperature compatibility. The suite of sensor technologies includes fiber-optic Distributed Temperature Sensing (DTS), in-fiber point source sensors typically of the Bragg grating type, and passive mechanical point source sensors that are read optically through an attached optical fiber.

All of these sensor technologies will require a means of passing the fiber out of the well. For land-based systems, this is relatively easily achieved through fiber packer systems. For subsea systems, this requires that a fiber-optic, wet-mate connection system be built into the x-tree prior to installation, and be capable of termination to the down-hole, fiber-optic gauge cable.

With fiber and fiber sensors in the well, there is also a need for reliable wet-mate and dry-mate fiber-optic connectors in the well to facilitate normal installation and work over practices.

The I-CONN connection system is compatible with both x-tree and down-hole environments.