Thin‐Bed Detection and Correlation with Instantaneous Frequency

Abstract

Synthetic models and field data show that anomalous instantaneous-frequency (both frequency spikes and frequency “events”) are clearly linked to bed thickness. Frequency spikes are related to relative amplitude minima along a seismic trace that occur either at the merging point of the top and base reflections of a wedge (type-I) or at the tip of the wedge (type-II). A type-II spike is indicative of a seismically thin bed (average 0.2λ or thinner in this study; λ denotes wavelength). Abnormal frequency “events” related to type-II spikes tend to follow geologically defined thin reservoir units. As a result, type-II frequency anomalies are useful in recognizing thin reservoirs that are otherwise difficult to detect and correlate. Uncertainties caused by type-I spikes and inadequate lithologic and timestratigraphic information can be reduced by integrating well data, local geologic models, and lithology-indicative seismic attributes.