(746b) Detection and Characterization of Gas Hydrate Deposition in Deadlegs Under Water Saturated Gas

Authors: 
Sa, J. H., Colorado School of Mines
Lee, B. R., Colorado School of Mines
Zhang, X., Colorado School of Mines
Askvik, K., Statoil
Li, X., Statoil
Austvik, T., Statoil
Kinnari, K., Statoil
Folgerø, K., Christain Michelsen Research
Haukalid, K., Christain Michelsen Research
Kocbach, J., Christain Michelsen Research
Sum, A., Colorado School of Mines
Deadlegs are specific pipe sections used in oil/gas production and transportation systems for management purpose. The fluids in deadlegs are stagnant due to the absence of flow. Once water evaporates from the main flowline, it readily condenses on the cold pipe wall of deadleg, and then forms gas hydrate deposits, which can eventually lead to plugging. A proper management of hydrates challenges in deadlegs is thus required for economic and safety reasons. Laboratory scale 1-inch vertical pipe system equipped with a permittivity probe has been developed to study hydrate deposition under water saturated gas environment. Here, we present how to characterize the hydrate deposition from a series of hydrate formation and dissociation experiments in terms of gas/water consumption, thickness/volume distribution, morphology change along the pipe, plug time/location, and porosity/wetness. In addition, the capability of a permittivity probe to detect water condensation and hydrate deposition on the pipe wall is described. Such qualitative and quantitative understandings would be essential in establishing strategies for hydrate risk management in deadlegs by providing guidelines on their design and operation.