Abstract
The oil industry has gradually accepted methane clathrate hydrate (MH) as an unconventional hydrocarbon resource. However, resource assessments and investment decisions for such new natural resources require field verifications of production technologies. Under the government-supported Japan's Methane Hydrate R & D Program, the MH21 consortium for MH resource development has carried out two onshore gas hydrate production tests in the Mackenzie Delta in the Canadian arctic with international collaboration, and plans offshore production tests in Japanese waters. The exploration drilling campaign in the Eastern Nankai Trough in 2004 revealed the resource size of hydrate deposits as well as the physical properties of hydrate-bearing sediments in this area. Information on formation properties such as pressure, temperature, and permeabilities taken from the first onshore production test in 2002 and the Nankai Trough exploration data, along with laboratory and numerical study results, suggest that simple depressurization, an energy efficient gas production method that is comparable to the primary recovery of conventional oil, is more feasible than previously considered. Thus, verification of the depressurization method and technologies were defined as objectives of the second production test undertaken by Japan Oil, Gas and Metals National Corporation (JOGMEC) and Natural Resources Canada (NRCan) in 2007 and 2008. Six-day gas production by depressurization produced 13000 m3 of gas from the hydrate reservoir in 2008, and led to the phase 2 study of MH21 in which the first offshore production test is planned for 2012.
