APPARATUS FOR GAS IDENTIFICATION USING HIGH FREQUENCY MICROWAVE CAVITIES

1 . An apparatus for gas identification, comprising:

one or more re-entrant microwave cavities, wherein each re-entrant microwave cavity comprises:

a tubular body having an exterior wall, a top portion, and a bottom portion;

an inner conductor positioned within the tubular body;

a measurement conduit positioned within the inner conductor and extending from the bottom portion to the top portion of the tubular body;

a cavity entry formed proximate the bottom portion, wherein the cavity entry is in connection with a first end of the measurement conduit and formed to receive one or more gases from below the tubular body;

a cavity exit formed proximate the top portion, wherein the cavity exit is in connection with a second end of the measurement conduit and formed to release the one or more gases from the tubular body; and

a high frequency connector attached with the exterior wall and configured to connect to a microwave source.

2 . The apparatus of claim 1 , wherein the measurement conduit is formed from a hydrogen-resistant material.

3 . The apparatus of claim 2 , wherein the measurement conduit is formed from a crystal material.

4 . The apparatus of claim 2 , wherein the measurement conduit is formed from a quartz material.

5 . The apparatus of claim 1 , further comprising a low-loss dielectric filling material between the exterior wall and the inner conductor.

6 . The apparatus of claim 1 , wherein the exterior wall is coated in a metal material.

7 . The apparatus of claim 6 , wherein the metal material is a Cobalt-Nickel-Vanadium alloy.

8 . The apparatus of claim 1 , wherein the cavity entry has a diameter in a range of 0.1 centimeters and 6 centimeters.

9 . The apparatus of claim 1 , wherein the microwave source is at least one single-port vector network analyzer.

10 . The apparatus of claim 1 , wherein the microwave source is at least one multi-port vector network analyzer.

11 . The apparatus of claim 1 , further comprising a plurality of hydrogen-resistant support structures attached with the bottom portion.

12 . The apparatus of claim 11 , wherein the plurality of hydrogen-resistant support structures are comprised of one or more of a fluoroelastomer, a perfluoroelastomer, and a nitrile rubber.

13 . A method for identifying a gas with the one or more re-entrant microwave cavities of claim 1 , comprising:

positioning the one or more re-entrant microwave cavities proximate a well;

collecting at least one produced gas from the well within the measurement conduit of the one or more re-entrant microwave cavities;

applying a microwave signal to the at least one produced gas;

measuring one or more properties of the at least one produced gas;

performing an analysis of the one or more properties; and

determining a purity of the at least one produced gas from the analysis.

14 . The method of claim 13 , wherein the at least one produced gas is at least one of hydrogen, carbon dioxide, and hydrogen sulfide.

15 . The method of claim 13 , wherein positioning the one or more re-entrant microwave cavities comprises arranging a plurality of re-entrant microwave cavities in an array proximate the well.

16 . The method of claim 13 , wherein the microwave signal is applied with at least one single-port vector network analyzer.

17 . The method of claim 13 , wherein the microwave signal is applied with at least one multi-port vector network analyzer.

18 . The method of claim 13 , wherein the one or more re-entrant microwave cavities are positioned near a surface pipe proximate the well.

19 . The method of claim 13 , wherein the one or more re-entrant microwave cavities are positioned downhole.

20 . The method of claim 13 , wherein performing the analysis further comprises obtaining a complex permittivity of the at least one produced gas.