| 摘要 |
A method and apparatus for determining the location of a material located behind an obstruction. A plurality of acoustic resonators (6) having a known resonant frequency are dispersed in the material (3), the material to be located on a first side of the obstruction (2). An instrument (5) is provided at an opposite side of the obstruction to the material. The instrument emits an acoustic signal and measures a response. If the resonant frequency is detected, it is determined that the material is located substantially adjacent to the instrument. The apparatus may be used for determining the height of cement slurry located between a well casing wall and a borehole. |
