| The "optimum window" seismic reflection method was used in an endeavor to further define an oil producing structure in the Traverse Limestone. This method entails using a source-geophone offset which allows desired reflections to arrive in an undisturbed time zone.;Several sources in the study area produced seismic pulses with relatively high dominant frequency components ranging from 80 to 120 hertz. However, only small charges of dynamite produced sufficient energy to penetrate the glacial drift in the study area.;Preliminarily identified reflection arrivals from the targeted horizon were consistently masked in seismic profiling records by high amplitude, low velocity seismic arrivals. Varied source offsets, digital filtering and seismic trace stacking failed to unmask desired reflections.;Well log and seismic refraction data coupled with seismic modeling suggest a clay layer caused velocity inversion within the glacial drift which generated high amplitude, low velocity multiple phenomena, thereby masking reflections from the targeted horizon. |
