Challenges of Flow Assurance in the Roncador Field

Abstract

Abstract Since 1987, with the beginning of the petroleum exploitation in Brazil in water depths deeper than 200 m, flow assurance has played an important role in the production of development projects. Especially in deep and ultra deep water production systems, waxes and hydrates can significantly impact the economics of the development project. Wax deposition in production flowlines invariable lead to production losses, and cleaning operations, such as pigging and/ or chemical removal has to be properly studied and carried out in order to minimize losses and maximize profits. This paper describes the main flow assurance problems and solutions carried out by the production of a deep water and long tie back system, the FPSO-Brasil, installed in a water depth of 1290 m, Roncador Field, since December 2002, and the prediction, prevention and remediation design criteria applied to the two new development Modules, which started production in the end of 2007. Among the problems and solutions that are described: FPSO-Brasil flow assurance production losses, practices used to mitigate flow assurance problems, use of lessons learned on the design and operation of the next Modules, hydrate and wax design criteria, and a study of an electrically heated pipe-in-pipe (EHPIP) system that combines a high passive insulation and active heating during shutdown and startup. Introduction The Roncador Field is located in the north area of the Campos Basin, Brazil, in an area of 111 km2 and in water depths ranging from 1500 m to 1900 m. Because of its large extension, high volume of oil in place, different fluid properties and the limited processing capacity of the production units, its development will occur in Modules: Module 1A Phase 1 (FPSO-Brasil) and 2 (P-52), and Modules 2 (P-54), 3 (P-55) and 4 (P-62). Since December 2002 the south area of Module 1A, Phase 1, has been producing by the FPSO-Brasil. The oil presents a strong tendency to wax deposition and gas hydrate blockage. The long flowlines (11-16 km), the low temperatures and high pressures have demanded regular pigging to remove organic deposits and cases of hydrate blockages sometimes required workover operations. The flow monitoring has been allowed to actively prevent and correct in situations of hydrate and wax blockages and in the optimization of the pigging frequency. In addition, paraffin inhibitor effectiveness has been evaluated. The Modules 1A Phase 2 and Module 2 are less susceptible to flow assurance problems, since the flowline lengths are shorter and the insulation is enough to ensure the project requirements. Operation procedures are used mainly to avoid hydrate plugging during shutdown and startup. The Modules 3 and 4 will not be mentioned in this work because they are still in the development phase.