| 摘要 |
<p>Well logging apparatus comprising a number of measuring electrodes (2) e.g. of metal, affixed in interspaced relationship on an earth drill (1) so as to be electrically insulated and serving to determine the electric formation resistivity in the earth strata traversed by the earth drill (1). The drill string of the earth drill (1) comprises a substantially cylindrical main drill stem (7) provided with an external helical rib (8) for conveying the drilled out earth up to the surface. The drill string wholly or partly in the longitudinal direction and certainly somewhat inwardly from the outer surface consists of an electrically insulating material (6) in which the measuring electrodes (2) are embedded.</p> |
