A multi-phase fluid stream having an initial gas phase and an intitial liquid phase is converted to a gas hydrate slurry. The initial liquid phase includes an initial water and the initial gas phase includes a hydrocarbon gas. An inert solid particle medium is entrained in the multi-phase fluid stream to form a fluidizable mixture which is conveyed through the interior of a heat transfer tube (26) enclosed within a shell (18). A heat transfer medium resides within the shell (18), but is external to the heat transfer tube (26) in fluid isolation from the fluidizable mixture. The wall of the heat transfer tube (50) provides a heat transfer surface for heat exchange between the multi-phase fluid stream and the heat transfer medium, cooling the multi-phase fluid stream on contact to a temperature below the gas hydrate formation temperature and converting at least a portion of the hydrocarbon gas and initial water to a plurality of solid gas hydrate particles. The solid particle medium substantially prevents accumulation of the solid gas hydrate particles on the tube wall (50). The fluidizable mixture is separated from the solid particle medium to recover a gas hydrate slurry containing the plurality of solid gas hydrate particles and the remaining portion of the initial liquid phase.