Guidelines for Subsea Hydrate Risk Management

Successful risk management for offshore production systems involving flow blockages is a critical element in the design, development and operational phases. Deepwater and ultra-deepwater production involves produced fluids and equipment facing cold temperatures of the sea water in long flowlines and subsea tiebacks at higher pressures of the new field developments. The low temperatures and high pressures create favorable conditions for hydrate formation and the potential for hydrate blockage during steady state, shut-in and cold restart operations.

Hydrates are uniquely challenging for subsea production as compared to other production issues such as corrosion, scale, paraffins or asphaltenes, as hydrate blockages can occur in a shorter time frame, are difficult to remediate and pose a significant risk to safety, health and the environment. Producers prefer to be prepared with multiple strategies from the design and operability point of view to reduce the risk from hydrate blockages, for the entire asset life/production cycle. A comparative study of the CAPEX and OPEX costs involving options such as insulation of subsea equipment (subsea trees, jumpers, manifolds, flowlines, etc.), hot oil circulation, electrical heating, subsea separation, blowdown and Dry-Oil Replacement, MEG regen systems, and hydrate inhibitors (Thermodynamic, Kinetic and Anti-Agglomerate) will be presented for a generic deep/ultra-deepwater development. The pros and cons for each of the previously mentioned options are discussed in order to provide guidelines for future developments.