Polyester rope is considered to be an attractive option for deepwater mooring systems. Polyester rope possesses many advantages over steel wire rope, however one of the major challenges in using polyester is an accurate understanding of the full scale physical properties. Further complicating this understanding is the variation in rope construction techniques employed by the rope manufactures. These differences may affect the individual performance and behavior of the polyester rope. This paper presents work done in addressing full scale design properties for the P-43 and P-48 FPSOs in the Barracuda and Caratinga fields, offshore Brasil in the Campos Basin in an average water depth of 800m and 1040m respectively. The paper discusses the initial characterization of the polyester rope properties for the engineering design of the mooring system and is based upon various data sources including industry data and Petrobras' past experience and testing. In addition, the paper examines the final development of the polyester rope specification and the resulting full scale qualification of four manufacturers based upon axial stiffness and minimum break load for their 1,250 tonne polyester rope design. Additionally, the recoverable and non-recoverable reep was determined for each manufacturer along with observations about the performance of the different rope constructions. Axial stiffness measurements are presented and compared with the data used during the mooring design and published formulations currently available in the public domain. Introduction Barracuda Field was discovered in June 1989, with the drilling of well 4-RJS-381 and the Caratinga Field in February 1994, with well 1-RJS-491. The Fields are located in central position in Campos Basin, two hundred (200) kilometers east of Macae, in a water depth varying from six hundred seventy (670) to one thousand two hundred (1200) meters and are separated by 12.5 kilometers. The Barracuda FPSO (P-43) is a Stena Concordia class VLCC converted into a FPSO unit with oil production capacity of 150,000 bopd, through 34 wells. The FPSO will be anchored in a nominal water depth of 800m at the Barracuda Field in Campos Basin offshore Brazil. The riser system consists of 81 production and export risers and umbilicals with the ability to accommodate an additional 26 future risers and umbilicals. The Caratinga FPSO (P-48) is also a Stena Concordia class VLCC converted into a FPSO unit with oil production capacity of 150,000 bopd, through 20 wells. The FPSO will e anchored in a nominal water depth of 1040m at the Caratinga field also in the Campos Basin offshore Brazil. The riser system consists of 51 production and export risers and umbilicals with the ability to accommodate an additional 26 future risers and umbilicals. The Caratinga FPSO is located twelve and a half kilometers southeast of the Barracuda FPSO. Each FPSO is spread moored by a taut leg mooring system using eighteen (18) mooring lines, ten (10) lines at the bow, and eight (8) at the stern for a twenty (20) year design life. The systems were designed to withstand the 100 yr storm condition according to API RP 2SK and ABS requirements as a permanent mooring system.

This paper presents the approach adopted for the design of the mooring and riser systems as part of the Barracuda and Caratinga field development project in the Campos Basin offshore Brazil. For deepwater field developments, where FPSOs are selected as the host facilities, an integrated approach is required for optimization of the riser and mooring system design. The principal parameters in the optimization process include vessel offsets, overall riser configuration and local pipe design. In the case of the Barracuda and Caratinga field developments, the integrated approach has resulted in a safe and cost-effective design, thereby enabling the use of a catenary configuration for the flexible risers. This paper further addresses the practical constraints typically encountered as part of the riser and mooring system design within the context of large-scale fast track deepwater field development projects. Introduction In July 2000, Halliburton was awarded a contract to proceed with the development of the Barracuda & Caratinga fields by the Barracuda and Caratinga Leasing Corporation (BCLC). The nature and scope was on a full engineering, procurement, installation and construction (EPIC) basis. This included work related to the drilling and completion of 54 wells, fabrication and installation of 133 flexible flowlines, risers and umbilicals, conversion and mooring of two very large crude carriers (VLCCs) into floating, production, storage and offloading vessels (FPSOs) and the commissioning, start-up and operations support for both fields. The project duration, from the time with a clear seabed to the point of handing over two working fully commissioned FPSOs in Barracuda and Caratinga fields, was about 3 years, representing a fast-track delivery schedule. The overall project specification and major deliverables is presented in Table 1. This scope of supply represents one of the largest of its kind ever awarded to a single contractor. The conversion schedule for the FPSOs was one of the most important factors to be considered in the riser and mooring system design. Several key schedule related issues to be considered during the design process include:Vessel dry-docking schedule;Vessel reinforcement interface loads;Mooring line chain size;Fairlead loads and fabrication lead time;Polyester rope prototype testing, production;Riser Design LoadsRiser manufacturing scheduleRiser pipe prototype qualification testing schedules;Riser ancillary equipment (endfitting, bend stiffener and abrasion protection and flowline anchor) schedules;Overall riser and mooring installation/pre-installation schedule. Based on the above, the project milestones are defined and these become the backbone to the process. Therefore as the design progresses along the schedule timeline, certain decisions are made for equipment design parameters. Once these are set, no further optimization can take place. As the imeline progresses the available options decrease. In short the degree of optimization of any piece of equipment is directly related to how far down the timeline the design parameters are required.

The FPSO Espirito Santo represents an exciting advance in ultra deepwater technology for floating systems. The FPSO, which arrived in Brazil 25 months after project sanction, is moored and operating in 1780 meters of water offshore Brazil in the BC-10 block (Parque das Conchas field development). The FPSO Espirito Santo is owned and operated by a joint venture between SBM Offshore and MISC, and leased to the BC-10 Joint Venture, operated by Shell, with partners Petrobras Brasileiro S.A. (Petrobras) and ONGC Campos Ltda (ONGC).The Parque das Conchas project presented many challenges to successful execution of the surface host facility. These challenges include the ability to receive, process and offload heavy crude ranging from 16-42 API grade and incorporation of unique design features into the hull to increase environmental protection and prolong the life of the 1975 converted VLCC hull. The water depth of 1780 meters and demands of the complex subsea infrastructure, which relies on continuous surface supplied power and circulated oil at critical stages, required careful consideration during execution. Finally, the selection of Steel Catenary Risers (SCRs) dictated a new design for the riser interface in the turret. The facility represents the first application of SCRs tied back to a turret moored FPSO.This paper provides a summary of the FPSO Espirito Santo design, fabrication, transportation, installation and start-up. The unique design aspects and technical challenges faced during the project execution phase for FPSO delivery are outlined. Subjects discussed include: execution planning; process facilities; hull and marine work scope; mooring system; and riser/umbilical interfaces with the host.The methodologies selected for overcoming the key technical challenges are presented. For processing produced oil covering a wide API grade range, including low API grade heavy oil, the use of multiple process trains with input heat is detailed. The hull systems include the use of cargo tank heating for offloading of heavy crude and utilize stabilized crude as ballast to prolong the hull service life. Dedicated hull tanks for subsea flow assurance fluids (methanol and light crude) also form part of the hull design, while sponsons have been incorporated during conversion of the single hull VLCC to provide double sided protection. The turret design required the application of novel concepts to accommodate the interface with SCRs and high voltage swivels to meet the subsea equipment power demands.

Designed to operate in Campos Basin Offshore Brazil, the FPSOs P43 and P48 are a considerable mark on the offshore industry in terms of the number of innovative engineering procedures developed for their design. As the FPSOs are going to operate as permanent floating production units at the same location for 20 (twenty) years, a complete dedicated design was performed considering the specific site conditions. This was carried out not only to determine mooring system and structural design aspects but also to predict and govern operational behavior in motion and stability, the object of this paper. Motion analysis of permanent offshore floating units is normally performed taking into account the specific site environmental conditions. On the other side, stability analysis is normally performed with worldwide limits criteria. The result of this is a predicted motion behavior based on the typical loading conditions and site environmental data that are not necessarily aligned with the stability limits of the unit defined by a minimum GM curve, eventually causing unexpected operational conditions. The main idea on the Barracuda and Caratinga project was to combine the stability limits of the unit with the predicted motion analysis typical operation conditions, defining a normal operation region where the FPSO will operate to guarantee a global performance in accordance with the predicted analysis. Based on the minimum GM curve derived from intact and stability analysis, new maximum and minimum GM curves were determined based on mass properties combinations where the motion response will be permanently inside the design parameters. The intent of this paper is to present the work performed to define the maximum and a minimum operational GM curves for the FPSOs, including motion and stability analysis, hull girder and local structural limits and a considerable amount of real operational considerations, that results in a general overview of a very refined global response design developed for a special project. Introduction Reviewing the usual procedures adopted to perform the stability analysis and global motion analysis of FPSOs, one realizes that the stability analysis normally considers the Unit as a ship calculated for unrestricted service. On the other hand, the global motion analysis considers the Unit as a fixed structure under the action of the specific site environmental conditions. It is easy to understand that the stability of a ship-shaped offshore unit shall be similar to the stability limit of a ship with the same hull forms, but motion analysis are normally performed for the expected operational load condition, not for the stability limit of the unit. For offshore floating units that are not able to store oil on board, like a semi-submersible platform, the stability limits are quite close to the expected load conditions, as there are few possibilities to vary the load of the unit the mass properties do not change very much. On an FPSO, the oil storage capacity weight is much larger than the vessel lightweight and consumables combined. The different possible combinations of the cargo tank loading can result in considerable different mass properties values for the same draft.

Quality inspection costs may vary depending on criticality and complexity of the components being manufactured. As a crude estimate, asset owners, operators, or EPC contractors may spend up to 5% of the cost of their components on inspection oversight. Manufacturing data are usually captured in a document referred to as Manufacturing Record Book (MRB) which is at best an enormous collection of scanned records. A digital framework was developed for Appomattox mooring components in form of a database with logical links among relevant records. This database is fully searchable to the finest level and guarantees traceability from the final product to its sub-components and all the way back to raw material manufacturing. This database is custom-made and is comprised of several bases which follow through natural manufacturing process for the specific product. Logical links are made for each accessory at different stages using its unique designated identification (ID). As such database is generated on the go as the component is processed, it gives manufacturer and end customer a strong Quality Control tool as well as an integrity management platform. Appomattox mooring inspection records were used as a case study to showcase robustness and flexibility of the developed database. Reference is made to [1] for general lessons learned from Appomattox mooring delivery.