As the industry's deepwater developments continue to mature, newer discoveries in the ultra deepwater demonstrate a trend towards more difficult and heavier hydrocarbons that are far removed from existing infrastructure. Since heavy oils represent a significant reserve-base, there is a strong economic incentive within the industry to develop technologies to profitably produce these hydrocarbon reserves. Heavy oils are often characterized by their high viscosity, low API gravity and low reservoir energy. Heavy oils are also prone to the formation of emulsions. The combination of these factors makes the production and transportation of heavy oils a major challenge from a flow assurance perspective. Development of a robust flow assurance strategy will play a central role in the system selection, detailed design, and operation of deepwater heavy oil fields. In this paper, we identify some of the most significant flow assurance challenges associated with heavy oil production and discuss technology developments needed to overcome them. In particular, we have focused our attention on viscosity management techniques and emulsion formation tendencies of heavy oils and also assessed the risk posed by solids such as hydrates, wax and asphaltenes. We also present a brief analysis of the operability aspects for producing deepwater heavy oils, describe major differences from conventional lighter oils, and evaluate its impact on the topsides infrastructure and subsea system selection and design.

Perdido is located in the Western Gulf of Mexico in 7,817 feet of water. It is being developed with cutting-edge subsea technologies to mitigate the project's key development challenges, which include extreme water depth, rugged seafloor terrain, low-pressure reservoirs, and aggressive hydrate formation tendency. This paper provides an overview of the Perdido Development subsea and flowline system and its associated flow assurance strategy. This paper also includes reviews of the design, fabrication, and installation of key subsea equipment such as twophase separators, subsea trees, manifolds, top-tensioned production risers, umbilicals, and flowlines. In particular, the two enabling subsea technologies, subsea boosting system and surface Blow-Out Preventer (BOP) for drilling and completing of subsea wells, are discussed. Unique features of the Perdido subsea system include:All wells are subsea (wet trees operated by umbilicals) and consist of 22 local Direct Vertical Access (DVA) wells and 12 offset wells.The subsea DVA wells are drilled, completed, and intervened through a single high-pressure drilling/completion riser and a surface BOP with the host rig.All production will flow from manifolds into five subsea boosting systems where gas will flow naturally to the topside facility, while liquids will be pumped using electrical submersible pumps (ESPs). Introduction The Perdido Development, jointly developed by Shell, BP, and CVX, includes the Great White, Silvertip, and Tobago fields and is located in the Perdido Basin and Foldbelt, in the Alaminos Canyon Protraction Area. This area is located in the western Gulf of Mexico, 200 miles south of Freeport, only eight miles north of the Mexico maritime border. All three fields are developed with subsea wells tied back to the host, which is a Spar with full offshore processing capabilities and pipelines for export.

The focus of flow assurance analysis and design has often been from flowline entry to the initial separator at the production facility. This paper focuses on the flow assurance issues that pertain to the well, with emphasis on the subsea well located in cold environments. Consideration is given to design and operational issues that result from management of flow assurance related to hydrates, with a brief discussion of other issues, such as wax, asphaltenes, and chemical compatibility issues.

The Perdido Regional Host is in the ultra-deepwater Gulf of Mexico, and produces from two Lower Tertiary horizons in multiple drill centers; some directly under the host SPAR, and others offset up to 7 miles and in water depths between 7800 and 9600 ft. All of the production is from relatively low-energy reservoirs, and posed considerable productivity challenges. The approaches to managing flow assurance risk and maximizing recoverable volumes were driven by the economically challenged environment in which the system was conceived and designed, and resulted in a unique host configuration relying on subsea wells and five high-powered ESP artificial lift systems with slug catching and two-phase separation accomplished on the seafloor. The final commissioning and early production characteristics of the system as related to the design intent and operational expectations will be described.The commissioning and early production phases of the development provided opportunities to validate Perdido subsea hydraulic models and operational methods that were considerably different from the typical approach employed by major oil companies in deepwater. Novel monitoring and surveillance tools generated by the project were benchmarked using early production data, and learnings were recycled into improvements to these models. This project is a considerable extension to previous systems, and due to the cost constraints of the risked recoverable volumes and high cost of operating in the ultra deep environment, it was imperative to advance the state of the art of flow assurance and operability.

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractBonga -the first Deepwater development in Nigeriacommenced production in Q4 2005. At an early stage of the project, flow assurance was identified as a key factor for successful development, noting: (i) complexities of the subsea network, including local downhill flow, (ii) logistical challenges of a new Deepwater basin, and (iii) reservoir fluids' propensity for solids formation, including additional risks posed by full-field waterflood.This paper discusses the key elements of the Bonga flow assurance strategy and its implementation in design and operations, with particular focus on the flow assurance performance of the subsea system during initial start-up. Comparisons of field data with analysis predictions include: (i) steady-state thermal-hydraulic performance, (ii) system thermal response during cold start-up, (iii) cooldown performance of subsea hardware and flowlines, (iv) system blowdown effectiveness, including the effect of riser gas-lift and (v) terrain slugging severity and gas-lift requirements.