| 摘要 |
<p>The invention relates to a method of determining a characteristic of a material selected from rock formation and cement, which material surrounds a borehole containing a fluid. The method comprises positioning an acoustic sensor at a selected position in the borehole, the acoustic sensor being suitable to provide signals representing acoustic emission from said material, applying a selected pressure to the fluid thereby inducing mechanical stresses in said material, said stresses inducing acoustic emission from said material. The sensor is induced to detect the acoustic emission and to provide a signal representing the acoustic emission. The characteristic is determined from said signal and from the pressure applied to the fluid.</p> |
