| 摘要 |
An electromagnetic wave propagation well logging system for measuring dielectric constant and/or formation resistivity (conductivity) includes three transmitters and a pair of receivers. The receiver pair is connected to circuitry that measures the amplitude ratio between the receivers, as well as the phase angle difference between the receivers. Signals representative of the detected amplitude ratio and of the detected phase angle difference are combined in such a manner as to make the depth of investigation controllable. Methods are also disclosed for maintaining a common depth of investigation as the well logging instrument traverses the earth borehole. |
