Electric Heating for Hydrate Prevention in an Arctic, Single-Line Tieback

Abstract

This paper proposes a mechanism for safe single-line tieback operation in arctic waters. Owing to arctic currents in this area, the seafloor can drop to subzero temperatures, leading to flow assurance challenges such as hydrate and wax deposition. Pipe-in-pipe insulation will prevent hydrate formation under normal production, and depressurization will maintain conditions close to hydrate formation. To prevent hydrate formation during restart, subsea electric heating will be applied to the production pipeline. Electric heating technology will significantly reduce displacement fluid and inhibitor requirements. Additionally, wax management in a single-line tieback will be enabled through the use of electric heating. Electric heating is a new technology to ExxonMobil for subsea application, with only one previous pilot to date. Melting a hydrate blockage with electric heating is a potential safety concern, and considerations for an intrinsically safe design for the heating technology are included in this work.