Achieving methane production from a gas hydrate-containing system under safe and economic conditions requires a fundamental understanding of the physical behavior involved in the dynamic process of methane hydrate formation and separation in sedimentary environments. In this study, by designing a laboratory device, the kinetics of methane hydrate formation in a porous silica environment with an excess water approach in offshore fields were simulated. Also, using volume balance calculations, the methane conversion fraction during different stages of hydrate formation and the saturation of phases in hydrate-containing sediments were obtained. The results of the temperature and pressure evolution diagrams during the methane hydrate formation process showed that the hydrate formation conditions for laboratory samples are in great agreement with the prevailing thermodynamic conditions. In proportion to the selected silica sand grain size, the average saturation of the hydrate phase was 32.5%, the saturation of the water phase was 63.9%, and the saturation of the gas phase was 3.6% for laboratory samples. Furthermore, the average methane to hydrate conversion fraction for test samples was 88.2%. Moreover, the difference in the thermal responses of the system at some positions of the thermocouples was attributed to the non-uniform distribution and formation of methane hydrate in the porous medium. Also, the studies showed that the amount of access of gas and water phases and the type of distribution of the hydrate phase in the sedimentary medium are important factors controlling the methane conversion fraction in the experimental samples. The simulation of the temperature and pressure conditions of the gas hydrate formed in this study also had a good agreement with gas hydrate reservoirs in offshore fields.