METHOD AND APPARATUS FOR INVESTIGATING EARTH FORMATIONS

摘要

A method and apparatus for investigating earth formations surrounding a borehole by injecting microwave electromagnetic energy into the formations and then taking measurments which relate to the propagation of such energy in the formations. In the preferred form of the invention, the injected microwave energy establishes a lateral wave which travels in the formations adjacent the interface between the mudcake and the formations. Energy signals from the lateral wave are received at first and second receiving locations. The phase difference between signals received at the first and second receiving locations is measured. Also measured is the relative attenuation as between signals received at the two receiving locations. The losscorrected dielectric constant associated with the formations surrounding the area between the first and second receiving locations is then obtained by judiciously combining the phase and attenuation measurements. Prior art methods have not met with much success at determining the true,dielectric constant of formations whereas the present invention can determine it.