Feasibility of a Microwave Meter for Water-Cut Measurements and Permittivity Profile

A microwave meter for geological applications is designed and tested through numerical simulations. It measures the reflection (S
₁₁
) and transmission (S
₂₁
) coefficients of the material under test (MUT), such as geofluids, oil spills, ice cores, rock cores or soil. The meter consists of pairs of waveguides whose ends face each other and are placed on the inner surface of the pipe/core holder. The waveguides have a diameter similar to that of the main pipe and are filled with specific low loss materials whose dielectric constant is close to that of the MUT. The waveguides are operated at or near the cutoff frequency of the TE
₁₁
mode of the waveguides, which for an optimum permittivity range of the MUT, allows for transmission of the TE
₁₁
mode in the pipe/core holder with little to no energy transmitted into other pipe modes. The permittivity profile is obtained from training sets that based on numerical simulations or by actual physical measurements. For water-cut measurements, results show an optimum range of sensitivity for specific water contents, which correspond to effective permittivity close to that of the waveguide filling material. These results can be utilized to monitor produced fluids at the well site and to obtain permittivity profiles.