Abstract

The paper relates to Marine Support systems for offshore pipeline terminals and production facilities. The contents of the paper are in three parts as under:

  • PART –A

    Mid life modifications of Offshore supply vessel (OSV) to task specific vessels

  • PART –B

    Economics of replacement of older Single Buoy Moorings (SBM"s) by new virtually maintenance free SBM"s

  • PART – C

    Dynamic Positioning (DP), and the human factor aspect in prevention of offshore accidents.

Marine floaters such as OSV's, SBM's and Floating Oil Storage and Off-take (FPSO) in the offshore Oil & Gas sector, are built for an economic life of 20 to 25 years. While the hull and machinery remain fit for purpose, for the entire economic life, the rapidly changing E & P technology and operational needs at times makes the vessels originally designed utility redundant.

The operational and economic benefits of mid life modifications / conversions of OSV's for gainful utility over the entire economic life are brought out in a case study of converting a general duty OSV into a task specific Offshore Terminal support Vessel. The study describes the methodology and approach for conversion / modifications and highlights how a single modified OSV can perform duties of tanker mooring assistance, floating hose handling, testing and replacement, SBM and subsea hose inspection & repair and fire fighting support. By focusing on task specific needs, the use of multiple specialized vessels can be avoided, thereby saving hiring and mobilizing expenses. It also avoids the dependence of external support which may be restricted or unavailable is some areas due political or other reasons of conflict.

Prematurely retiring still useable old technology assets by new technology enabled assets, provides cost effective and positive gains and justifies early equipment replacement. Switch over to new technology enabled SBM's provides for lower life cycle maintenance cost and virtually no operational down time for over 25 years. A case study of operational and economic benefits of replacing a still useable Turntable SBM by a Turret type SBM is presented to high light the cost effectiveness and other advantages of new technology and methods

During the early days of offshore oil field development, the OSV's were operated and maneuvered using the practical ship handling skills of the Master/ Captain. The handling skills varied from person to person and were prone to accidents due to the human factor. The use of D P vessels provided a wider safety umbrella while operating in close vicinity of Offshore Installations; however they could not be a total solution to the human factor. A case study regarding an OSV drift incident while on duty station at a Floating Production & Storage and off-take (FPSO) is presented. The incident highlights the element of human factor along with some Marine operational corrective recommendations.

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