Modelling of ch4 production through the depressurization method from bjornoya gas hydrate basin using reactive transport simulator

Abstract

Natural gas hydrates (NGHs) cannot reach thermodynamic equilibrium in real reservoir conditions. The enormous amount of methane stored in NGHs could be a potential source of energy. Lack of reliable field data makes it difficult to predict the production potential, as well as the safety of CH4 production from NGHs. Computer simulations cannot substitute field data. Nevertheless, state of the art modelling can be used to evaluate possible long-term scenarios. However, we need proper kinetic models to describe hydrate dissociation and reformation and all phase transition routes must be considered. In this work, we utilized an in-house extension of RetrasoCodeBright (RCB) to perform a gas hydrate case study of the Bjørnøya basin, based on very limited geological data extracted from reported field studies. The aim of this research was to use a reactive transport simulator and non-equilibrium thermodynamics to analyse CH4 production from the gas hydrate. Results show fast propagation of pressure drop wave throughout the reservoir layer by imposing drawdown pressure on the well, as a result, gas hydrate dissociation and CH4 production started at the early stages of the five year simulation period.