Sand production modeling of the 2013 nankai offshore gas production test

A better understanding of the behavior of gas hydrate-bearing sediments during gas extraction is a vital step towards realization of long-term gas production for the future. In March 2013, the world first trial of gas production from offshore hydrate-bearing sediments by depressurization method was conducted at the Eastern Nankai Trough site, Japan. While the operation was successful in producing gas, after six days it suddenly encountered a large amount of sand migration into the well, a phenomenon known as sand production, leading to a premature termination of the operation. This incident has highlighted the importance of development of sand migration model within hydrate-bearing sediments and understanding of the geomechanical behavior of hydrate-bearing sediments with the effect of sand migration during gas extraction. This paper presents the overview of the recently developed thermo-hydro-mechanically coupled formulation that entails sand migration in gas hydrate-bearing sediments. The formulation is then applied to simulate the 2013 Nankai production test in wellbore scale, including history matching of produced water and gas. The amount of produced sand at the end of the test is also matched and the effects of sand migration on geomechanical behavior are investigated.