ABSTRACT

This paper presents a lateral approach to subsea production control, the intelligent umbilical or MANTA concept. The concept eliminates the need for a discrete subsea control package and a topside hydraulic power unit by placing both in the subsea end termination of the control umbilical. The bottom line is that this approach provides superior system reliability and can be shown to have major economic advantages.

The object of the exercise is to provide a system which will control the production of hydrocarbons from a remote location on the sea bed cheaply, effectively and reliably.

The MANTA concept is based on a novel combination of proven technology. This effectively provides for a high reliability system combined with significant reduction in the cost of ownership. At the same time, the concept is, by its very nature, able to take full advantage of all the very best aspects of up to the minute technology.

The MANTA will be found particulary attractive for applications in marginal remote field developments.

INTRODUCTION

The production of hydrocarbons from under the oceans of the world is now considered an everyday event. The MANTA concept is a logical step forward in the evolution of underwater production control. The MANTA approach has evolved from the integration of a combination of already proven subsystems. This amalgamation of ideas has provided a system which has both improved reliability and a clearly demonstrated reduction in the cost of ownership.

The MANTA is seen to meet a number of the major industry requirements for a sound but flexible basic subsea production control system package.

The subsea control systems being installed today are, in a number of ways, at least 10 years out of date. Technology has advanced, the industry meanwhile would seem to have stood still or in some cases gone backwards. To some extent this is understandable, Oil Companies are in the business of producing oil and gas - not hardware. Any field development is a risk. Limiting the initial investment helps reduce the risk to what would seem to be a sensible minimum.

The problem with this approach is that while the Company wants 10 year old fully qualified technology, the initial budgets are limited. Suppliers therefore in order to be competitive, are forced to look for ways of reducing costs and/or of meeting specification which, again on limited budgets, have often been generated by very inexperienced personnel. The nett result of this conglomeration of sometimes conflicting ideas and requirements is generally a further compromise to the ‘standard’ equipments performance.

Current and traditional systems exhibit inherent weaknesses which are amplified by economic pressures. Platform space allocation is nearly always marginal. J tubes are almost always too small. The size and weight of both surface and subsea equipment invariably presents major installation and deployment problems and, subsea equipment failures, although not an every day event, are nearly always attributed to either infant mortality, tramp contamination in the hydraulic system or degradation failure of underwater installed interfaces.

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