ROV Installable Electrohydraulic Connector
Authors: Dean J.L. , Simmons Colin , Cini Joseph 
Published: October 2008

This paper describes the design, testing and installation phases of a cooperative effort between FSSL, Inc., Oceaneering, Slingsby Engineering, Ltd., and Subsea International in developing an ROV installable electrohydraulic connector to meet the requirements of BHP Petroleum for its Griffin Field. The effort resulted in the design of a method that improves system reliability, reduces equipment costs, and can be employed by RO Vs regardless of their manufacturer.

INTRODUCTION

Conventional techniques for installation of subsea umbilicals, either by diver or ROV, involve a jumper umbilical. One end of the jumper umbilical is connected to the tree control module; the other end is connected to an umbilical termination plate. The umbilical itself is terminated to the other side of this umbilical termination plate. Typically, these terminations use some combination of wet-mateable, proprietary electrical connectors and special purpose, high pressure hydraulic connectors. Often, the hydraulic connectors employ metal-to-metal seals and also include components made of exotic metals to resist the effects of high pressure service and the corrosive environment in which they are used.

The conventional methods require at least three connections for each line, both electrical and hydraulic, and in multi-well applications can represent a million dollars or more in equipment costs. BHP Petroleum's field required eleven such subsea installations, so improved umbilical connections offered substantial economic incentives. But BHP Petroleum's area of concern focused upon the reliability effects of the three subsea connections typically used in each line.

One third of the connections in each line could be eliminated if a factory installed termination at the control module were connected directly to the subsea umbilical termination plate. Further operational improvement could also be obtained if the technique could be completed entirely by ROV, without the assistance of divers. BHP Petroleum required the make-up to be performed by ROV because divers are not available when control modules are worked over during completion activities.

DESIGN PHASE

BHP first had FSSL engineer a preliminary design to meet its specifications. The preliminary connector design consisted of two captive electrohydraulic junction plates which incorporated handling and locking mechanisms designed for a Slingsby TA9 seven function ROV manipulator. (See Figure 1.) In this early design, the junction plates were fabricated from 3/4" titanium plate, and each plate contained two 1/4" stainless steel, hydraulic connectors which had metal-to-metal seals and elastomeric backup seals. These are rated for 10,000 psi working pressure. A male wet-mateable Challenger Marine electrical connector was also mounted on each removable plate.

To facilitate the span of movement and control for the ROV manipulator, each junction plate was mounted on a control arm that extends from the control module. The extension arm provides a zone of control in which a dropped junction plate can be retrieved by the ROV. It can gimbal inward and outward relative to the subsea tree, and also extend or retract relative to he control pod to install the junction plate at a second station, or parking receiver.