Seismic Azimuthal Anisotropy: an Important Tool for Detection of Coal Bed Methane, an Unconventional Source of Energy- a review

Methods of measuring seismic azimuthal anisotropy are being used increasingly to detect fractures in reservoirs. Coal reservoirs are usually more abundant in fractures than any other ore bodies. However, not all the fracture nets have the same feature, neither can they lead to the same permeability and the same anisotropy. In coal exploitation, research on fractures is of vital importance in guiding the layout of working faces, mining and driving, the exploration and development of coal bed methane, the maintenance of roadways and the prevention of water and gas bursts. Therefore, to be able to forecast the direction and density of fractures in coal seams is of great importance for safe production and high efficiency of coal mining. This suggests that estimates of seismic anisotropy can be used for detecting cleats in the coal bed methane (CBM) reservoirs. In this paper we are going to present a review work of the application of azimuthal anisotropy estimated from a small 3D, shot over an area in Western Canada known to contain significant coal beds, and shows that significant seismic anisotropy is associated with them. This suggests that estimate of azimuthal anisotropy can be used for optimizing CBM reservoir management in the future.