ABSTRACT

This paper gives an overview over current methods for intervention on subsea production, flow and process control equipment Replacement of intrusive sensors, light weight modules such as control modules, multiphasemeters and choke inserts is addressed, in addition to replacement of medium weight modules such as booster pumps and pig launchers/receivers Emphasis is put on today's solutions, including the operational availability of these methods under varying metocean conditions A short historical background to the subject is given, as well as some views on what is expected to take place in this field in the near future

INTRODUCTION

Kongsberg Offshore a s (KOS), being a supplier of complete subsea production systems to the oil and gas industry, is concerned that all equipment in the companies product range perform as an integrated part of the total system This means that effort is put into optimising the equipment with respect to design and performance, interfaces to neighbouring equipment, installation procedures, intervention equipment and - procedures, as well as equipment CAPEX and OPEX in order to minimise the Life Cycle Cost (LCC) of the subsea production equipment

In order to obtain these goals, it is required to understand not only how the equipment should be designed to be able to operate in the subsea environment, but also how it is most efficiently installed, operated and maintained

This paper addresses intervention on subsea production-, flow- and process control equipment in light of the above system approach.

The topics that are addressed are taken from KOS's earlier and present projects, and in particular from the Technology Agreement project This project, terminated at the end of 1997, was a three year NOK 110 Million development project, starting as a joint effort between KOS and Statoil, and later joined by Mobil, Elf and Shell The result of the project is the deep water HOST (Hinge Over Subsea Template) system capable of producing oil and gas in 2500 meter water depth.

CATEGORIES OF RETRIEVABLE COMPONENTS

The following three categories of retrievable subsea components for production-, flow and process control are addressed in this document (the Table is available in full paper)

SHORT HISTORICAL OVERVIEW

In order to provide a background for the current status of retrievable components, three typical examples of retrievable components from earlier KOS projects during the last ten years, are presented

  • The ROV retrievable intrusive pressure sensor

  • The ROV retrievable Control Module

  • The Universal Running Tool (URT) for Control Modules and Gate Valves

ROV retrievable intrusive pressure sensor

The sensor is shown in figure 1 The sensor housing was disconnected and re-connected by a patented flat-to-flat collet connector Isolation from the process bore was provided by a small ball valve The sensor was a prototype, brought forward by a BP and Saga funded development project, and was completed by performing shallow water tests in 1988.

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