Evaluation of Pipeline Configurations with Active Heating for Export of Waxy Crude Oil

Abstract

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractInsulation and active heating options evaluated for transportation of waxy crude oil in an 8-inch flowline from a platform 10 miles offshore. Two bundled pipeline configurations are studied, and the results are compared with conventional pipe-in-pipe and a non-jacketed insulated pipe. The crude has a high pour point (PP, 91°F) and a high wax appearance temperature (WAT, 105°F).A solution is provided that allows the crude to stay above WAT. The non-jacketed pipe option is not thermally efficient; the pipe-in-pipe option can keep the crude oil warm during normal flow; but high storage capacity is required at the platform, which makes the solution impractical. The bundled pipeline configurations maintain the crude oil temperature above WAT thus avoiding waxing and gelling during steady state flow and during restart operations.Despite being more expensive, the bundled pipeline configuration proved to be the right solution for this particular field. The results of this study are applicable for evaluations of similar field developments.

An Overview of Flow Assurance Heat Management Systems in Subsea Flowlines

“…The conservation and line start over by active heating method permit the change to a single line framework that presents significant cost gains through a reduction in the number of flowlines from a conventional circuit system with chemical injection and dead oil circulation [160,[163][164][165]. The active heating system involves the external addition of heat to the production flowline by an electrical heat source or circulated hot water [166,167]. The active heating technique is an attractive, economical, and effective solution for flowline heat management systems particularly in subsea deepwater fields where flowline pressure and temperature conditions are unfavorable [49,50].…”

“…Hot water circulation technology was used in Conoco Phillips' Britannia fields and Statoil's Gullfak [50,167]. Brown et al [174] narrated the design and execution of the UK North Sea, Britannia 15 km subsea hot water heated bundle project [49]; regarded as the finest solution for preventing the formation of hydrates and wax [49].…”

Untitled

“…The wax formation can be mitigated by heating, thermal insulation of pipelines, and injection of chemical additives [7][8][9]. Due to the relative simplicity of application, efficiency, and cost-effectiveness, the use of chemical additives for the control of wax is a widely adopted technique [10].…”