Frequency Dependent, Structurally Conformable Filtering

At low frequencies, data have inherently poor spatial resolution, and are thus inherently over-sampled by 3D marine data. We recently demonstrated (Whitcombe & Hodgson, 2005; 2007) that large spatial filters can be applied to post-migration low-frequency data without degrading signal: a large spatial averaging filter can be thought of as spatial stacking, which will not smear the data provided the operator size is comparable to the spatial wavelength. This technique is particularly useful for inverted data, which relies heavily on low frequency information. These lower frequencies enhance the imaging of thick pay intervals, and help avoid the occurrence of false high impedance beds within the middle of such low impedance layers. Additionally, the extra low frequencies improve the linearity of the calibration & calculation of seismic net pay from the layer SNA (sum of negative amplitudes) attribute.