DIELECTRIC CONSTANT MEASUREMENT METHOD

• US 3,675,121 A
• Filed: 06/26/1970
• Issued: 07/04/1972
• Est. Priority Date: 06/26/1970
• Status: Expired due to Term

• Current Assignee: Don D. Thompson
• Original Assignee: Don D. Thompson
• Inventors: Thompson, Don D.
• Primary Examiner(s): Smith, Alfred E.
• Application Number:
  US05/050,022
• Time in Patent Office: 739 Days
• Field of Search: 324/61
• US Class Current: 324/664
• CPC Class Codes: G01N 2027/222 for analysing gases
• CPC Class Codes: G01N 27/221 by investigating the dielectric properties using microwaves G01N22/00; measuring loss factors or dielectric constants per se G01R27/26
• CPC Class Codes: G01N 27/223 for determining moisture content, e.g. humidity rain detectors on vehicle windows B60S1/0825
• CPC Class Codes: G01R 27/2676 Probes
• CPC Class Codes: G01V 3/088 operating with electric fields G01V3/082 takes precedence

Abstract

The real part of the complex dielectric constant of a fluid medium containing conducting impurities and water is accurately measured by avoiding the effects of dielectric dispersion and water dipole absorption. Dielectric dispersion is avoided by operating the capacitance probe circuit at a frequency above about 10 megahertz. Water dipole absorption is avoided by operating a capacitance probe circuit at a frequency below about 300 megahertz.

Claims

1. The method of measuring more accurately at low concentrations the water content of a water-in-oil emulsion by determining the real part of the complex dielectric cOnstant of said water-in-oil emulsion whose measured dielectric constant is not adversely affected by the contribution of dielectric dispersion and water dipole absorption due to clay particles in said emulsion which method comprises inserting a capacitance probe into said waterin-oil emulsion, driving said capacitance probe by an alternating current circuit with a frequency within the range from 40 megahertz to 300 megahertz, measuring the capacitance of said capacitance probe in said water-in-oil emulsion and calculating the real part of the complex dielectric constant, Epsilon '"'"''"'"', of said emulsion by means of the formula:

Epsilon '"'"''"'"' C/Co, where Co equals capacitance of the circuit in a vacuum and C equals the capacitance measured in the medium.

2. The method of claim 1 wherein said capacitance probe is driven by an alternating current circuit with a frequency within the preferential range of 70 to 150 megahertz.

3. The method of measuring more accurately the real part of the complex dielectric constant of a water-in-crude oil emulsion containing conductive inorganic colloidal impurities, such as clay, to determine the water cut of said emulsions which avoids the conduction effects of said water and inorganic particles, which method comprises inserting a capacitance probe into said emulsion, driving said capacitance probe by an alternating current circuit at a frequency within the range from 40 megahertz to 300 megahertz, measuring the capacitance of said capacitance probe in said emulsion, calculating the real part of the composite dielectric constant of said emulsion by means of the formula:

epsilon '"'"''"'"' - C/Co, where Co equals capacitance of the circuit in a vacuum and C equals the capacitance measured in said emulsion, and indicating the water cut of said emulsion in accordance with the formula;

wherein;

V water water cut of said water-in-oil emulsion, epsilon w 79 (the real part of the dielectric constant of water), epsilon o 2.30 (the real part of the dielectric constant of crude oil), epsilon '"'"''"'"' the real part of the measured dielectric constant.

4. The method of claim 3 wherein said capacitance probe is driven by an alternating current circuit with a frequency within the preferential range of 70 megahertz to 150 megahertz.

5. The method of measuring the real part of the complex dielectric constant of a water-in-crude oil emulsion containing conductive clay particles which avoids the conduction effects of said clay particles and which avoids the dipole absorption of said water so that said real part of the complex dielectric constant varies more directly with the percentage of water in said water-in-crude oil emulsion where the concentration of water is less than about 10 percent, which method comprises inserting a capacitance probe into said water-in-oil emulsion, driving said capacitance probe by an alternating current circuit at a frequency within the range from 40 megahertz to 300 megahertz, measuring the capacitance of said capacitance probe in said water-in-oil emulsion, and calculating the real part of the complex dielectric constant of said water-in-oil emulsion by means of the formula:

epsilon '"'"''"'"' C/Co, where Co equals the capacitance of the circuit in a vacuum and C equals the capacitance measured in the medium.

6. The method of claim 5 wherein said capacitance probe is driven by an alternating current circuit with a frequency within the preferential range of 70 megahertz to 150 megahertz.

7. The method of measuring with greater accuracy the water cut of a water-in-oil emulsion at concentrations of water of less than about 10 percent water wherein said emulsion contains sufficient clay material to adversely affect the accuracy of said measurement which comprises subjecting a sample of a water-in-oil eMulsion to an electric field at a frequency of from 80 megahertz to 120 megahertz across a pair of capacitor plates, and measuring the real part of the dielectric constant of said emulsion present between said plates as an indication of said water cut without error introduced by the conductivity of clay impurities in said water at concentrations of water of less than about 10 percent in said water-in-oil emulsion.