Formation of hydrate in injection of liquid carbon dioxide into a reservoir saturated with methane andwater

Abstract

Injection of liquid carbon dioxide into a depleted natural gas field is investigated. A mathematical model of the process which takes into account forming CO₂ hydrate and methane displacement is suggested. An asymptotic solution of the problem is found in the one-dimensional approximation. It is shown that three injection regimes can exist depending on the parameters. In the case of weak injection, liquid carbon dioxide boils up with formation of carbon-dioxide gas. The intense regime is characterized by formation of CO₂ hydrate or a mixture of CO₂ and CH₄ hydrates. Critical diagrams of the process which determine the parameter ranges of the corresponding regimes are plotted.