| 摘要 |
<p>Appts. for measuring the equivalent dia. of a deep hole into the earth, esp. a prospecting borehole of small dia., comprises a long sonde, which can be lowered into the hole, e.g. by means of a cable. The sonde is equipped with a gamma ray detector and has arms fixed to its body and distributed uniformly around it. One part of each arm carries a source of gamma radiation, and tends to expand elastically away from the body of the sonde to make contact with the wall of the hole. There are means of retaining the arms against the body of the sonde whilst it is being lowered, which can be controlled from the surface. Used for the determn. of the equivalent dias. of small boreholes prospecting purposes. The device makes possible geophysical investigation without the necessity for the extraction of samples mechanically. The device is simple, inexpensive and functions efficiently. When the arms have come into contact with the wall of the borehole a count is taken, and from this the equivalent of the hole can be calculated. At the surface a curve of the variations may be traced as a function of the movement of the sonde and the dia. at each level deduced from a standard curve.</p> |
