With the anticipated development of a large number of deepwater fields offshore in the Gulf of Mexico. There is a need for the owners and operators of the field to evaluate a fixed versus disconnectable turret moored system for FSO's and FPSO's in terms of CAPEX, OPEX and system availability during service life which impacts Lost Production and Risk. These two turret mooring systems are each unique and result in differences in general arrangements, operational characteristics and life of field costs. The selection of which turret mooring system for a FSO or FPSO is complex as it depends on a variety of factors including environmental conditions, field layout, production rates, storage capacity, offloading frequency and tropical storms and hurricane shutdown.

This paper presents information and results that allow a structural evaluation of fixed versus disconnectable turret moored FSO's and FPSO's from a technical, commercial and operational viewpoint. The objective of the paper is to provide a guide to the decision making process of the appropriate selection of the FSO or FPSO based on comparative turret mooring and fluid-transfer issues, CAPEX, OPEX, Lost Production and Risk due to tropical storms and hurricanes.

This paper compares fixed and disconnectable turret mooring systems by:

Defining typical design parameters for the two systems; .

Evaluating the turret mooring and fluid-transfer systems; .

Contrasting the engineering, procurement, construction and field installation costs (CAPEX); .

Assessing operational consideration such as system availability, Lost Production, product offloading and OPEX for life of field; and.

Evaluating Risk due to hurricanes.

The example used to illustrate the selection process between the two systems is a generic field in the offshore oil and gas fields in the Gulf of Mexico. The example presents results from the global analysis to allow comparison of the mooring and riser performance and availability of the production and offloading systems. Cost estimates of the two systems are presented showing the breakdown among various components and comparisons between the two based on CAPEX, OPEX, system availability, Lost Production and Risk.

This paper provides a mechanism to help owners and operators to evaluate FSO and FPSO options with both types of turret mooring systems

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