High - resolution seismic reflections to delineate coal beds > 350 m deep , with some < 3 m thick , under Fort Yukon , Alaska

High-resolution seismic reflection methods were instrumental in characterizing a coalbed methane prospect estimated to have the potential to produce sufficient methane to satisfy the municipal needs of rural Fort Yukon, Alaska. Reflections with upper corner frequencies over 200 Hz and dominant frequencies over 150 Hz were recorded sitewide. Over a dozen uniquely distinguishable reflections are interpreted within the 300+ m deep coal interval. These data permit delineation of any coal beds thicker than 5 m within this interval. Reflection wavelets possessed sufficient consistency and uniqueness for individual reflection events to tie between lines separated by over 2 km. Horizontal resolution of these data allow the mapping of subtle stratigraphic features varying over 10s of meters. A series of very small offset faults trending to the southwest and synforms with northeast/southwest axis are inferred from basement topography and high amplitude reflections between basement and the base of ice bonding. Extending the borehole information, it appears top and bottom of the coal seam was imaged. Interpreting the geologic significance and setting of subtle depositional geometries evident on the seismic section will be possible with additional ground truth. Speculating based on local geology and reflection characteristics, high amplitude, coherent reflections between about 350 and 500 ms may be from coal reflectors.