Thermo-hydro-mechanical sand production model in hydrate-bearing sediments

A better understanding of the behavior of hydrate-bearing sediments during gas extraction is a vital step towards realization of commercially viable gas production for the future. In 2007, the world first trial of gas production from hydrate-bearing sediments by depressurization method was conducted at the Mallik gas hydrate site, located in the Mackenzie Delta of Northwest Territories, Canada. However, the operation encountered a large amount of sand migration into the well, a phenomenon known as sand production, and thus was terminated after 24 hours. This incident highlights the importance of development of hydro-mechanical sand production model within hydrate-bearing sediments and understanding of the behavior of hydrate-bearing sediments with the effect of sand production during gas extraction. This extended abstract provides a formulation for the sand production including grain flow and hydraulic dispersion effect. A formulation is fully-coupled such that the sand production affects fluid pressures, saturations and temperature. In addition, the effective stress reduction due to grain detachment is incorporated. This results in further deformation of hydrate-bearing sediments, which may need to be considered for stability of the wellbore.