Effect of Porous Media and Sodium Dodecyl Sulphate Complex System on Methane Hydrate Formation

Abstract

Hydrates are mainly stored in the pores of the sedimentary layer, so their formation and storage characteristics in pores are particularly important for the exploitation and utilization of hydrates. Meanwhile, in order to study the rapid formation methods of hydrate, 300 ppm of sodium dodecyl sulfate (SDS) solutions mixed with alumina and silica particles, respectively, were used for investigating the hydrate formation in the pores of porous media under the conditions of 275.15 K and 7 MPa. The particle sizes of alumina and silica were 2, 4, and 6 mm. The experimental results indicated porous media with smaller size could shorten the induction time of the hydrate formation and increase the final gas uptake. In dissolution period and induction period, gas consumption of hydrate formation in alumina particles was larger than that in silica, but the reverse in the growth period. The hydrate formed in alumina particles had a better gas storage ability. In the used SDS solution, the positive charges produced by hydrolysis on the alumina surface and the negative charges produced by polarization and hydration on silica surface affected the distribution of the SDS active group around their surface, which led to the difference of gas storage density between the hydrates formed in these two particles. Finally, with the formation of the hydrate on the wall of the porous medium, the stronger capillary force caused by the decreasing pore size led to a migration of water, which further resulted in the hydrate form in the pores without SDS solution originally.