Abstract: In a logging tool which transmits electromagnetic radiation into adjacent formations, and including such tools which operate as low as 20 Khz (typical for induction logs) up to as high as the gigahertz range, an improved antenna system is set forth. The antenna preferably transmits a circular polarized signal so that reflected and refracted return constituents in the receiver signal can be sorted out. For intermediate frequencies, the antenna can be potted in a high dielectric constant material.

Abstract: A method and apparatus for dielectric investigation in formations adjacent a well borehole is set forth. In the preferred and illustrated embodiment, a microwave transmitter forms and output signal which is transmitted by a transmitter antenna in contact with the sidewall, the propagation into the formation from the transmitter antenna, the signal being received at a receiving antenna, and further including means for making measurements of amplitude and phase angle. Such measurements are used to determine an equivalent circuit representative of the formation between the transmitter antenna and receiver antenna; the equivalent circuit encodes valuations of resistivity, dielectric constant and magnetic permeability of the formation material. Multiple measurements can be made in a given formation, and the sonde can be moved steadily or periodically to make measurements at selected locations. Formation electrical parameters in adjacent formations can then be determined.

Abstract: An improvement in signal level reception of an electromagnetic pad-type device in relatively conductive formations can be achieved by providing a layer of dielectric material that abuts the borehole wall and serves to enhance injection into the formations and guiding of the electromagnetic energy.

Abstract: An apparatus and method for determining the amount of adsorbed fluid in formations surrounding a borehole. In accordance with the present invention, means are provided for deriving a first quantity which is a function of the dielectric constant of the formations as measured by passing electromagnetic energy of a first frequency through the formations. Means are also provided for deriving a second quantity which is a function of the dielectric constant of the formations as measured by passing electromagnetic energy of a second frequency through the formations. Finally, means are provided for determining the amount of adsorbed fluid in the formations as a function of the difference between the first and second quantities.

Abstract: An apparatus and method for determining the amount of adsorbed fluid in formations surrounding a borehole. In accordance with the present invention, means are provided for deriving a first quantity which is a function of the dielectric loss factor of the formations as measured by passing electromagnetic energy of a first frequency through the formations. Means are also provided for deriving a second quantity which is a function of the dielectric loss factor of the formations as measured by passing electromagnetic energy of a second frequency through the formations. Finally, means are provided for determining the amount of adsorbed fluid in the formations as a function of the difference between the first and second quantities.

Abstract: A method and apparatus for investigating earth formations surrounding a borehole by injecting microwave electromagnetic energy into the formations and then taking measurements 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 loss-corrected 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.

Abstract: A method and apparatus for investigating earth formations surrounding a borehole by injecting microwave electromagnetic energy into the formations and then taking measurements 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 loss-corrected 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.