Methane Hydrate Formation, Storage and Dissociation Behavior in Unconsolidated Sediments in the Presence of Environment-Friendly Promoters

Abstract

Abstract Methane hydrate in the porous medium is formed within the pores of the sediments. The presence of a porous medium enhanced the heat transfer, whereas the presence of a hydrate promoter could enhance the mass transfer between the liquid-gas interface. In this study, we have studied the effect of sediment particle size and type of promoter on the kinetics of the methane hydrate formation and dissociation in the combined system. Environment-friendly amino acids (L-valine, L-methionine & L-histidine) and surfactant Sodium dodecyl sulfate are used as a promoter with four different particle sizes (46.4-245 μm, 160-630μm, 480-1800μm, 1400-5000μm) silica sand. Isothermal experiments are carried out using 3000 ppm promoter concentration at 100 bar, 274.15°C using the rocking cell to investigate the induction time, gas uptake, hydrate saturation. Temperature is further lowered to 266.15K to investigate the dissociation behavior of methane hydrate to study the self-preservation effect in the combined system. The experimental results show that induction time in the combined system decreases as a sediment particle size decreases. Gas uptake remained unchanged in the combined system by changing the sediment particle size. We also report similar formation kinetics of hydrophobic amino acids (L-valine, L- methionine) and SDS at four particle sizes. At similar hydrate saturation, SDS has displayed weaker self- preservation effects compare to a hydrophilic amino acid in the porous medium. Results in this study, support the conclusion available through other studies at lower concentration (500 ppm) of SDS and provide additional information about formation behavior at higher concentration (3000 ppm) of SDS. Results collected in this research could be beneficial in the selection of environmentally friendly chemicals for rapid methane hydrate formation in sediments to be used either in laboratory studies or for natural gas storage and transportation.