2018 年 13 巻 4 号 p. JFST0028
The objective of this study is to visualize the flow pattern in methane hydrate (MH) reservoir model under atmospheric pressure condition. A method to mimic a real MH reservoir was introduced into the present research to visualize the multiphase flow pattern in porous media under thermal fluid injection. First, porous media mimicking real MH reservoir were prepared in a visualization cell with dual horizontal wells, which were composed of glass beads, ice of sodium bicarbonate (NaHCO3) aqueous solution and ethanol (C2H5OH). Thereafter, hydraulic fracturing by injecting C2H5OH aqueous solution was executed to generate flow path that increases permeability between the injection well and production well. The flow pattern in the reservoir model with the flow path was then visualized during the injection of hydrochloric acid (HCl) aqueous solution. The dominant factors governing the multiphase flow in fractured porous MH mimicking reservoir were evaluated. It was found that the flow path formation with high permeability by hydraulic fracturing and permeability increment by ice melting are of critical importance for the reservoir mimicking system. In addition, it is found that the liquid phase flow may also be affected by the formation of gas phase inside the porous media that mimic the dissociation process in the real MH reservoir.