| 摘要 |
<p>PROBLEM TO BE SOLVED: To measure the resistivity of mud filling a well pit. SOLUTION: Resistivity of mud in a well pit is measured by means of a measuring probe 26 connected with the bottom part of an apparatus. The probe comprises a bottom electrode 32, a second electrode, and at least one measuring electrode 36 disposed contiguously to the bottom electrode 32, and a current flows between the bottom electrode 32 and the second electrode when the prove is energized. The current is discharged at first from the bottom electrode 32 into the mud and flows substantially in parallel with the longitudinal direction of apparatus when it is received from the mud by the bottom electrode 32. Since the measuring electrode 36 is disposed contiguously to the bottom electrode 32, voltage drop in the region of mud located directly under the bottom electrode 32 is measured and controlled by a current discharged principally from the bottom electrode 32 and flows through that region before being by the bottom electrode 32.</p> |
