51 2. Refraction surveying Determining the delay times, and the arrival times of the refracted wave picked on the two constant-offset sections, enables the calculation of the refractor velocity at any point (Figure 2.10-b). Picking the direct arrival on geophones close to the shot point provides the weathered zone velocity (Figure 2.10-c). Determining the delay, the refractor velocity and the velocity of the weathered layer enables the calculation of the static correction at any point (Figure 2.10-d). Figure 2.11 and 2.12 are an example of the results obtained using the Chronos method. Figure 2.11 shows, from top to bottom, the variation of velocity V1 of the weathered zone along the line, the variation of the refractor velocity, the delay time curve, the topography and the static correction curve. The static correction curve shows an anomaly between shot points 60 and 110. Figure 2.12 shows the seismic section processed with the static corrections presented in Figure 2.11. Figure 2.11 Static corrections with the Chronos method (Coppens, 1985).
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