19^th International CODATA Conference
Category: Gas Hydrates

3D Modeling for Defining Gas Hydrate Potentialities

Jean-Jacques Royer (Jean-Jacques.Royer@ensg.u-nancy.fr)
Computer Science Department, ENSG-CRPG, France

Gas hydrates (GH), a mixture of solid water and gas (usually methane in natural GH), are central in the debates on energy and global change issues. They may offer an alternative energy resource for future generations (as recently mentioned in Science, Kerr, 2004 [13]). The amount of hydrated energy is twice that of all other fossil fuel energy sources combined. Several scientific research programs have been launched both at National level (Japan, 1995, 2001; India, 1996; China, 2002; USA 1982, 2002; Russia; Europe, 1996) and international level. The understanding of this unconventional gas deposit, is essential to resolve major societal questions such as energy reserve and recovery, climate change, global carbon budget, and seafloor hazard stability.

However, it appears that there is a lack of information for defining gas hydrates potential zones, especially in marine environment. This paper investigates the possibility of using 3D modeling at the basin scale in order to estimate the potential stability window of gas hydrates in a marine environment. This methodology includes (i) a full 3D geometrical model of the geological formation; (ii) the estimation of the 3D thermal field of lithologies solving the temperature equation; (iii) the calculation of the pressure in 3D at depth. This various 3D models are then used to define the stability conditions of gas hydrates using a standard equation of state for gas hydrates assuming a given composition for natural gas hydrates. The methodology has been implemented in Gocad, a 3D modeler developed for modeling complex natural object in geosciences. This methodology has been applied on several illustrative case-studies such as margins including the Angola basin, the off-shore Brazil margins and the New Caledonia Farewell Basin. These examples illustrates the lack of data and references values in the field of gas hydrates, a question recently addressed by the Codata Task group on Gas Hydrates. With the support of ICSU and several national committees, Codata has launched a task group on Gas hydrates in 2000 to fill the gap of scientific information lacking, and especially of databases on standard values. One of the unexpected results of this activity is the increase in international cooperation programs.