Reliability-Based Design Criteria for Floating Drilling & Production Structures in the Bay of Campeche
Authors: Bea R.G. , Xu T. , Ramos R. , Valle O. , Valdes V. 
Published: October 2008

This paper summarizes Risk Assessment & Management (RAM) based criteria that have been developed by Petroleos Mexicanos (PEMEX) and Instituto Mexicano de Petroleo (IMP) for design of floating drilling and production structures located in the Bay of Campeche, Mexico. The RAM approach addresses the primary structural components that comprise floating drilling and production systems, reliabilities of the components and systems based on economic and standards-of-practice methods, operating and environmental conditions, life-cycle quality assurance and control programs including inspections, maintenance, and repairs, proposed analytical models used to determine structure loadings and capacities (Working Stress Design format, Load and Resistance Factor Design format, and Limit State Design format), variabilities and uncertainties in the demand and capacity parameters, and proposed measurement, observation, and monitoring programs. These criteria have been founded on guidelines developed by the American Petroleum Institute for floating drilling and production structures.

The criteria summarized in this paper address hurricane characteristics in the Bay of Campeche, strength characteristics of the structures, damaged and defective conditions that can develop in the structures due to accidents, and the unique capacity characteristics of the elements that comprise floating structures including the surface structure elements and mooring systems. The criteria are 'information sensitive' so that as additional information is gathered on the demand (loading) and capacity characteristics, then the criteria can be changed in response to the new information. The criteria are 'quality' sensitive so that as improved quality assurance and control and advanced marine structural integrity programs are utilized, the effects of these programs are reflected in the criteria.

Introduction

These hurricane design criteria have two primary parts:Definition of the procedures and parameters to be used in design to characterize the hurricane conditions and forces, andDefinition of the procedures and parameters to be used in design to determine the sizing of the primary structural components in deep water floating systems.

The definition of design environmental conditions was based on the studies of hurricane conditions in the Bay of Campeche performed by Oceanweather.1,2 The definition of rocedures to be used to determine the forces acting on floating structure components were founded on the American Petroleum Institute (API) guidelines for design, analysis, and maintenance of moorings for floating drilling and production systems3,4, design of tension leg platforms5, design of fixed offshore platforms6, and design and analysis of risers for floating drilling units.7

The definition of the procedures to be used to determine the sizing of the primary structural components in floating systems are founded on the API guidelines for design, analysis, and maintenance of moorings for floating drilling and production systems,3,4 the guidelines for planning, designing, and constructing tension leg and fixed offshore platforms,5,6 and the API guidelines for design of cylindrical shells and flat plate structures.8,9