Self-Preservation Effect for Hydrate Dissociation in Water plus Diesel Oil Dispersion Systems

The self-preservation effect experiments in water + diesel oil dispersion systems for methane hydrate were carried out with the particle size ranging from tens to more than 100 mu m. The influence of water cuts (low water cuts of 10, 20, and 30 vol % or high water cuts of 95, 99, and 100 vol %) and types of inhibitors (tetra-n-butylarnmonium bromide or Lubrizol) on the dissociation kinetics in oil and water suspensions were examined. The addition of surfactants, especially those able to lower the size of droplets or hydrate particles in low water cut suspension systems, could remarkably hinder the self-preservation effect by surface adsorption and alterations in structures and morphologies of ice film. For higher water cut systems with or without surfactants, the enhanced self-preservation effect was observed in comparison to lower water cuts. Systems with oil exhibited a declined effect in contrast to pure water systems. The ice-shielding mechanism for hydrate dissociation is supported by the effects of surfactants and water cuts on dispersion and agglomeration properties as well as the size of hydrate particles.