| 摘要 |
<p>Discontinuities, e.g. fractures, in the strata are detected by measuring the mean value of a physical magnitude characteristic of a stratum, particularly electrical resistivity or speed of propagation of sound waves, over a short interval between a first and second level in a borehole, at different positions of these levels separated by a constant distance, and by taking an average depth reading for each measured value between the first and second levels, differentiating the measured values of the physical magnitude with respect to the depth, and correcting the two values found for the derivative for a first and second depth reading separated by the constant distance, whereby both such values depart from zero when a geological discontinuity exists near the borehole at a depth equidistant from the first and second depth readings.</p> |
