2014 年 79 巻 6 号 p. 377-390
Unconventional oil and gas attract attention as next generation energy, because of their vast amount of resources. A part of the unconventional oil and gas has been already produced on a commercial scale, while the development of some of them is still in the stage of research. Reservoir modeling and simulation are now playing an important role towards the development planning for unconventional oil and gas. This paper first gives an outline of unconventional oil and gas, from the viewpoints of reserves, development/production methods and problems/challenges. Then, some examples of reservoir modeling and simulation specializing in unconventional oil and gas resources are introduced.
Two main methods of cold production and thermal method are being applied to the development of heavy-oil/extra-heavy-oil/bitumen. For the simulation predicting cold production performances, it is requested to reproduce the incremental oil recovery due to foamy oil flow and wormholes. For the production by thermal methods, several innovative simulation studies are reported. Examples of such simulation include the automated optimization of steam injection strategies, reproduction of the combination of steam and solvent injection and thermal simulation of advanced in-situ combustion.
For shale gas/oil development, reservoir modeling and simulation are focusing on the characterization of the area of high productivity (so-called ‘sweet spot’). To clarify the mechanism of fluid flow in sweet spots, sensitivity studies are conducted using not only simple double porosity/permeability models but also more complicated multi-porosity/permeability models.
The research work for the development of methane hydrate has started recently. Although the superiority of the depressurization method has been revealed through numerical simulation, the recovery of methane by depressurization is predicted to be not more than 50-60%. The methodologies that can be applied in conjunction with and/or after depressurization are being pursued. Displacement of methane with carbon dioxide is expected as one of such methods.