Numerical Simulation of Laboratory Experiments On Methane Hydrate Dissociation

Pawar, Rajesh J. (Los Alamos National Laboratory) | Zyvoloski, George A. (Los Alamos National Laboratory) | Tenma, Norio (National Institute of Advanced Industrial Science and Technology) | Sakamoto, Ysuhide (National Institute of Advanced Industrial Science and Technology) | Komai, Takeshi (National Institute of Advanced Industrial Science and Technology)

OnePetro 

ABSTRACT

We present results of numerical simulation of dissociation behavior of methane hydrates in laboratory experiments conducted at the Institute for Geo-Resources and Environment in Tsukuba, Japan. The hydrate was formed in packed sand columns and the dissociation behavior was studied under different stimulation conditions including hot-water injection and/or pressure reduction. A number of variables including amount of gas produced, temperature along the column and pressure difference across the column were monitored. A numerical model for hydrate behavior was developed, based on the FEHM (Finite Element Heat and Mass) Computer Code, the Los Alamos National Laboratory (LANL)''s in-house porous flow simulator. Capability to simulate the general behavior of hydrates in porous media was added to the simulator, including the kinetic, thermodynamic and heat transfer processes. Multiple conceptual models were used to simulate the experimental data. The simulation results indicate that incorporation of both dissociation and hydrate formation is necessary to better match the experimental data.

INTRODUCTION

Hydrates of methane gas represent a substantial energy resource. It is believed that methane stored in hydrate form may exceed the energy content of the total fossil fuel reserves (Makogan, 1988, Kvenvolden, 1988). Despite the vastness of this resource, it is not yet significantly exploited. A large amount of work has been done to understand fundamental behavior of pure gas hydrates (Sloan, 1997). On the other hand, hydrate behavior in porous media is not yet completely understood. Improving understanding of the fundamental hydrate behavior in porous media such as its formation/dissociation behavior, fluid flow behavior is important in order to determine effective production strategies. A number of researchers have reported work related to hydrate behavior in porous media. Selim and Sloan (1990) reported on hydrate dissociation experiments using hot water injection.