Early geophysical papers of the Early geophysical papers of the Society of Exploration Geophysicists earlygeophysical00soci Year: 1947 2 B. B. WEATHERBY AND L. Y. FAUST PROCEDURE The type of data which were analyzed is shown in Figure i, where velocity-depth curves from three wells are plotted slsAA, BB, and CC. These curves have been determined in the usual manner by well shooting. The procedure is to place a charge of dynamite in a hole 20-70 feet deep located about 1,000 feet from a well. A geophone is lowered into the well to some measured depth and this geophone records the time of the
Early geophysical papers of the Early geophysical papers of the Society of Exploration Geophysicists earlygeophysical00soci Year: 1947 2 B. B. WEATHERBY AND L. Y. FAUST PROCEDURE The type of data which were analyzed is shown in Figure i, where velocity-depth curves from three wells are plotted slsAA, BB, and CC. These curves have been determined in the usual manner by well shooting. The procedure is to place a charge of dynamite in a hole 20-70 feet deep located about 1,000 feet from a well. A geophone is lowered into the well to some measured depth and this geophone records the time of the first arrival of energy from the exploded charge. The straight-line distance from the shot to the geophone, Depthdn feet) Fig. i.—Results of velocity determinations in three wells. Average velocity from sur- face to given depth is plotted against that depth. divided by this time, gives the average velocity of the section to the depth of the geophone. The velocity so determined is somewhat lower than the average velocity along the actual path of the ray. The actual path of least time is slightly curved and therefore would yield a greater average velocity. The geophone is then lowered to some other depth and another measurement of time is secured and the velocity cal- culated. It is these velocities plotted against depths of the geophone below the casinghead which are shown in Figure 1. These curves represent the average velocity of a section from the surface to any depth plotted against that depth. Since the velocity of the first 1,000 feet of material, for example, enters into the velocity 662
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