Downhole pulse radar
First Claim
Patent Images
1. A downhole radar tool for use with a system for detecting and locating fractures in a geological formation near a borehole, said tool comprising:
- a generally cylindrical housing sized to move within a borehole;
transmitter means for generating a pulse having a broad distribution of power over the frequency range from 30 MHz to 300 MHz as a pulse radar signal;
transmitting antenna means, connected to said transmitter means, for transmitting said pulse radar signal from said tool into the geological formation;
receiving antenna means for receiving a reflected radar signal from said geological formation;
isolator means for isolating said receiving antenna from said transmitted pulse radar signal; and
signal processing means for processing the reflected radar signal received by said receiving antenna means;
wherein each of said transmitting and receiving antenna means is a directional antenna comprising;
a reflector antenna consisting of a straight radiator and a metal reflective surface parallel to and spaced from said radiator;
a cylindrical pipe made of electrically insulating material and forming a hollow shell;
said reflector antenna being contained within said shell, said radiator being parallel to the axis of said pipe, the volume from an interior surface of said pipe to said reflector including said radiator defining an electromagnetically active region; and
dielectric material filling said electromagnetically active region, said material having a dielectric constant within the range of 20 to 150.
1 Assignment
0 Petitions
Accused Products
Abstract
A borehole logging tool generates a fast rise-time, short duration, high peak-power radar pulse having broad energy distribution between 30 MHz and 300 MHz through a directional transmitting and receiving antennas having barium titanate in the electromagnetically active region to reduce the wavelength to within an order of magnitude of the diameter of the antenna. Radar returns from geological discontinuities are sampled for transmission uphole.
103 Citations
13 Claims
-
1. A downhole radar tool for use with a system for detecting and locating fractures in a geological formation near a borehole, said tool comprising:
-
a generally cylindrical housing sized to move within a borehole; transmitter means for generating a pulse having a broad distribution of power over the frequency range from 30 MHz to 300 MHz as a pulse radar signal; transmitting antenna means, connected to said transmitter means, for transmitting said pulse radar signal from said tool into the geological formation; receiving antenna means for receiving a reflected radar signal from said geological formation; isolator means for isolating said receiving antenna from said transmitted pulse radar signal; and signal processing means for processing the reflected radar signal received by said receiving antenna means; wherein each of said transmitting and receiving antenna means is a directional antenna comprising; a reflector antenna consisting of a straight radiator and a metal reflective surface parallel to and spaced from said radiator; a cylindrical pipe made of electrically insulating material and forming a hollow shell;
said reflector antenna being contained within said shell, said radiator being parallel to the axis of said pipe, the volume from an interior surface of said pipe to said reflector including said radiator defining an electromagnetically active region; anddielectric material filling said electromagnetically active region, said material having a dielectric constant within the range of 20 to 150. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
-
Specification