METHOD OF DERIVING WATER BOTTOM REFLECTIVITIES IN THE PRESENCE OF GEOLOGIC INTERFERENCE

摘要

In a marine seismic survey, water bottom travel times are obtained by conventional methods. Near offset seismic data are then dereverberated using a suite of possible water bottom reflection coefficients to give a suite of filtered traces. The water bottom reflectivity that gives the minimum value over the suite of processed traces is determined to give a set of selected reflectivities each of the analysis points within a time window. A weight is determined for each analysis time within the time window, the weight being related to the change in the amplitude of the filtered trace at that sample point over the suite of water bottom reflectivities. The selected reflectivities are weighted by the weights and averaged to make a determination of the water bottom reflectivity. This determined water bottom reflectivity is used to process the recorded seismic trace. This determined water bottom velocity may also be used to obtain the upcoming dereverberated wavefield in a dual sensor array wherein a hydrophone-geophone combination is used to record data at the ocean bottom.