METHOD OF FIRST ARRIVAL PICKING OF SEISMIC REFRACTION DATA

摘要

The method of first arrival picking of seismic refraction data is embodied in software that uses the τ-p transform on energy-ratio seismic records. First, the seismic shots are gathered. Next, the energy ratio (ER) is computed, and then the τ-p transform of the energy ratio is computed. Using a binary mask, a corresponding first arrival energy is selected. The transform is combined with the binary mask and presented as input to an inverse τ-p transform. The inverse transform data is then thresholded, and indices of ER first arrivals are detected based on the thresholds. The software then creates a vector of indices or time samples of picks. This method can be used to better guide the subsequent careful picking of first arrivals. Moreover, the method automatically interpolates missing picks.

主权项

1. A method of first arrival picking of seismic refraction data, comprising the steps of
obtaining field records of seismic data detected at a plurality of seismic receivers in an area of interest, the seismic data including signal amplitude data recorded over time and containing both first arrival reflection signals and unwanted noise; calculating the signal amplitude data in an offset-time domain, the signal amplitude data being formulated as energy ratio amplitude data characterized by the relation:ERj=∑i=ji=j+LAi2∑i=1i=j+LAi2  where ERj is the energy-ratio value associated with a sampling window starting with the jth sample of a trace of the energy ratio amplitude data and Ai is the signal amplitude of the ith sample of the trace; applying a Radon transform to the energy ratio amplitude data, thereby transforming the energy ratio amplitude data from the offset-time domain to a time-slowness domain; selecting a corresponding first arrival energy data from the time-slowness domain energy ratio amplitude data, the selection generating a binary mask wherein a binary 1 indicates a required first-arrival picks region with a τ-p energy ratio map and a binary 0 indicates that the region is not a required first-arrival picks region; multiplying the Radon transformed energy ratio amplitude data with the binary mask to form a Radon transform energy ratio amplitude data-binary mask product; applying an inverse Radon transform to the Radon transform energy ratio amplitude data-binary mask product, thereby transforming the Radon transform energy ratio amplitude data-binary mask product into the offset-time domain; and binary thresholding in the offset-time domain the inverse Radon transform of the product, thereby producing an enhanced binary image in the offset-time domain of the selected first arrival region.