3D visualization of methane hydrate production behaviors under actual wellbore conditions

Abstract

This study aimed to give a better visualization of the hydrate dissociation and gas production behaviors during methane hydrate production under actual wellbore conditions via 3D images. A real 3D methane hydrate reservoir model was built in this study, and three different types of production methods using horizontal wells (depressurization or hot water injection) were designed. Meanwhile, the gas production and fluid flow behaviors under actual wellbore conditions were revealed through 3D visualization. The simulation results indicated that for the depressurization scenario, the pressure loss in the wellbore mainly affected gas production at the early stage of the depressurization process, while the effect on the long-term gas production behavior was not quite significant. However, for the hot water injection scenario, the heat and flow losses in the wellbore both had great influence on the gas production and fluid flow behaviors, which would cause the decrease in gas production and have a negative impact on the processes of heat transfer, hydrate dissociation, and gas-liquid two-phase flow in the reservoir. Especially, at the end of 1.5 yr, the decrease in total gas production caused by the flow loss (19.4%) was much larger than that caused by the heat loss (4.1%). Therefore, for the future field trials and further investigations on 3D visualization of the actual methane hydrate production process, such losses in the wellbore should be taken into account for the accurate prediction of the long-term gas production behavior.