Reflection field methods
Published:January 01, 2004
For simplicity we assume 9 channels only with 3 groups per section, as diagramed in Figure 8.1a. The circles at the left represent the intake to the recording system, the arrows → and ← represent the connectors at each end of the sections. When two sections are connected, the takeouts for the right-hand section are rotated three channels as shown in the figure. Note that the section is symmetrical; the end pin on the left (#1) relates to the closest takeout, as does the end pin on the right (#9). So flipping the section end-for-end makes no difference. If we connect three sections with nine groups as shown, the profile will be recorded correctly. However, if a 4th section is connected at the right, the rotation will have gone full circle and we will have distant geophones connected to the same channels as near geophones, as shown in Figure 8.1a.
Figures & Tables
Problems in Exploration Seismology and their Solutions
Geophysicists are often turned off by equations. This is unfortunate because equations are simply compact, quantitative expressions of relationships, and one should make an effort to understand the information that they convey. They tell us what factors are important in a relationship and their relative importance. They also suggest what factors are not relevant, except perhaps through indirect effects on the relevant factors. Graphs often help us visualize equations more clearly. We may think of derivatives as simply measures of the slopes of curves, maxima and minima being merely the places where the slopes are zero, and integration as simply summing up the area under a curve. An imaginary exponential indicates a periodic function. Limitations imposed by initial assumptions or by approximations in their derivations apply to most equations, and these should be appreciated in order to avoid drawing erroneous conclusions from the equations.