Abstract

Based on Kværner's steel tube umbilical technology and fabrication facilities in Moss (Norway) a new generation steel tube umbilical (IPU") that will give significant cost savings to the oil industry is being developed.

The main advantages of this new product are reductions in both CAPEX and OPEX and associated cost savings due to the reduced need for sub-sea flow-line and umbilical infrastructure.

This new technology will provide fully integrated and reliable transportation of well fluids, electrical and fiber optic power/signals, hydraulic and injection fluids, and high voltage power. Thermal insulation, temperature monitoring, and electrical or hot water heating provides flow assurance. Applications ranging from shallow water down to water depth beyond 2000m are considered fully achievable.

Introduction

To effectively meet the requirements of future subsea developments an Integrated Production Umbilical (IPU?) is being developed. The IPU is designed to combine the normal function of an umbilical with that of a production or an injection line, and also for supplying high voltage power to potential subsea users. Suitable flow assurance in the flowline is achieved through a combination of thermal insulation and active heating.

The IPU concept is based on the steel umbilical technology that Kvaerner has developed and successfully implemented during the past decade. When comparing with today's solutions for tying subsea wells back to a processing installation, the IPU will offer several benefits. Its envisaged range of application includes shallow and deep water, remote wells, and demanding wellstream conditions. But, a number of questions need to be resolved and, before this new product gets accepted, it must be demonstrated that it is qualified for its intended purpose.

A development program is presently under way and the intention of this paper is to give an overview of the progress that has been achieved so far. The key issues addressed from early on are related to functional aspects, where flow assurance is a key element. Focus has therefore been on:

  • Heating of the flowline, both thermal and electrical.

  • Temperature monitoring.

  • HV power distribution.

In addition, the use of the IPU in a dynamic application has been examined in order to ensure its application in deeper water.

But before going into details on the above issues, the paper will present a general description of the IPU and its application potential, and an overview of the on-going qualification plan.

IPU Description and Applications

Figure 1 presents an exploded view of the IPU, which basically consists of the following elements:

  1. A large bore central pipe, 6"-12", suitable to transport well fluid, water, gas or any other fluid that is required in large quantities.

  2. Around the central pipe, an annular shaped PVC matrix that keeps in place the spirally winded umbilical tubes and cables and provides thermal insulation to the central pipe.

  3. Embedded in the PVC matrix, but sliding freely within it,

  4. the various metallic tubes for heating, hydraulic and service fluids, and the electrical/fiber-optic cables for power and signal.

  5. A protective sheath in polyethylene or similar material.

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