Subsea Systems Innovations and the Use of State of Art Subsea Technologies Help the Flow Assurance of Heavy Oil Production in Ultra-Deep Waters

Abstract

Flow assurance in ultra-deep waters oil production is always a major concern. Atlanta field, which produces heavy oil in ultra-deep waters, is one of the most challenging project offshore combining several difficulties: hydrates formation, emulsion tendency, scale formation, foaming, high viscosities that can achieve 100.000 cp at sea bed temperatures, etc. To overcome these challenges, the best subsea system technologies has been used, together with some small, but ingenuous, innovations. The use of a 6" unbonded flexible lines, with TEC 2 insulation layers minimize the risk high viscosities in case of the expected shut downs. To cope with scales, foaming and emulsion, chemical additives can be deployed into the wells through the biggest and unique umbilical installed in Brazil, which accommodates 15 hoses, 2 MV Electrical Cables of 3X150mm2 and 2 Eletrical Cables with 4x6mm2 and 2 eletrical cable of 4x2,5mm2. Hydrates can block the flowlines stopping the production. When it occurs, the remediation is normally long and expensive. For hydrates, the cliché "prevention is better than remediation" is true. Hydrates can be prevented with proper procedures and preventers. But in case of hydrate formation, a pioneer hydrate mitigation panel, operated by ROV was installed in the wet christmas tree (deployed by cables). And finally, to guarantee the production flexibility for production and maintenance, an innovative and unique subsea lay out, consisting of two Electrical Submersible Pump (ESP), one in-well and other in mud line skid, was developed and installed. All this innovations and best technologies used together made Atlanta a successful case of heavy oil production in ultra-deep waters, triggering huge resources around the world.