Qualification and Assessment of Subsea Insulation Systems

Abstract

As offshore oil and gas production continues to push into deeper waters, subsea production systems are challenged to manage the inherently higher operating temperatures and pressures. As a consequence of their direct exposure to seawater, subsea “wet” insulation systems on subsea trees, manifolds, and jumpers are amongst the most affected by this progression. Due to the significant thermal gradient between the production stream and subsea environment, subsea insulation systems are constantly trying to inhibit the natural heat transfer. In an effort preserve the operational integrity of the production system, the subsea insulation system maintains the production stream temperature above the hydrate formation and wax deposition temperatures. Thus, any failures such as cracks, disbondment, or hydrolysis, substantially influence the subsea system’s operational philosophy. As a result of ExxonMobil’s observed performance challenges with wet insulation systems, a thorough qualification program was initiated in 2007 to validate the performance of a wet insulation system under simulated service conditions. The qualification consisted of 3 test phases, including basic material property tests, simulated service tests, and an extended service test, for multiple insulation systems. This paper presents an overview of select subsea insulation failures, the qualification program, and subsequent assessment of key material properties, such as tensile strength/elongation, density, and hardness.