The Dubai Floating Storage System
Authors: Greff D.E. , McClure A.C. , Williams R.E. , Norton J.A. 
Published: October 2008

Two former tanker forebodies have been converted to remote controlled, instrumented unmanned floating oil storage vessels. These vessels are for use by Dubai Petroleum Company in the Fateh Field 60 miles off the coast of Dubai, Trucial States, Arabian Gulf. Background information, results of feasibility studies, conceptual and detailed design and engineering developments leading to the final conversion of two former 50,000 ton tanker forebodies and their integration into the production, storage and off-loading facility are discussed.

Included in the detailed design aspects is information on:—a unique underwater pumping and manifolding system;—gravity fill and discharge system from production platform to vessels via submerged pipe line andflexible hoses through vessel's bottom;—the simplification of the vessel's original internal cargo distribution system to permit safe, unattended cargo loading and discharge operations while maintaining trim and stability within satisfactory limits and adequate resist to damage throughout the range loading conditions from empty to full load;—the investigation of the dynamic effects of the loading/discharge cycle on the vessel using analog computer techniques;—the in-depth analysis of the mooring which resulted in some unusual features including relatively short scope and an assymetrical arrangement;—features of the control and instrumentation design;—safety and five protection features;—reliability and maintainability features.

INTRODUCTION

In June, 1966, the Fateh A-I well tested oil in two zones and heralded the entry of Dubai into the ranks of oil producing countries. Dubai, a Trucial State on the southern shore of the Arabian Gulf (Figure 1), is an established center of commerce operating through its shallow water port. But the shoreline in this area yields no natural deep water port essential for crude oil export in deep-draft tankers. Consequently, the Fateh Field location 58 miles offshore in 110 to 190 feet of water (Figure 2) offered both opportunity and challenge for the field owners. Deep water in the field area offered the opportunity to load tankers on site. The challenge was to develop a self-contained offshore storage and loading system that would not only save investment dollars, but operate dependably and cost competitive with the more conventional pipeline-to-shore storage method.

Dubai Petroleum Company, a subsidiary of Continental Oil Company, operates the concession for a multi-national group of oil companies. The other participants are British Petroleum Company and Compagnie Francaise des Petroles acting together as "DUMA" (Dubai Marine Areas, Ltd.), Deutsche Erdol-Aktiengesellschaft, and Dubai Sun Oil Company.

Floating storage as a temporary facility was considered by the group in the earliest stages of field exploration, and two disabled tankers were purchased for that purpose. After the present design was conceived and subjected to a feasibility study, the total offshore system was adopted for long-term field exploitation. The two vessels already purchased were retained for conversion to the first storage units of a nominal 100,000 BID initial development program. A detailed design study was launched, culminating in the installation described in these pages.

Since the project was initiated, another promising offshore storage method - a large volume submerged storage unit - has proved feasible.