Utilizing First and Second Derivative Seismic Trace Amplitudes to Map Paleo-Glacial Valleys

Explaining variation in reservoir thickness from well data and geological models can be challenging when dealing with non-uniform depositional nature. A common example is glacial valley distribution cutting into deep marine shale. Reservoir thickness varies tremendously at the same depth in valley centers, valley edges or outside the valley. Moreover, valleys have different geometries including sharp edges (U-shape) valleys and softer edges V-shape valleys. The spatial variation of geometrical change also introduces another aspect of complexity in mapping these valleys. The architecture of glacial valleys cutting into shaly stratigraphic units has the advantage of soft to stiff contrast which can be imaged by 3-D seismic. The glacial process of carving melted ice and sediments into shale is chaotic, leaving an imprint of elongated valleys that can be mapped in seismic stratigraphic slices and seismic cross sections. On seismic 2-D cross sections, the valley walls can be traced with limitations due to the seismic quality and complexity of structuration. Advanced seismic interpretation methods are utilized to enhance the cross-section resolution and reduce the uncertainty in mapping the glacial valleys. These methods include deriving seismic trace first and second derivatives to sharpen the amplitude contrast in viewing the seismic images. Advancing the glacial valleys mapping techniques has a direct impact on updating gross depositional environment maps and interpreting the paleo topography.