System and method for determining water-filled porosity and water salinity in well cores and logs
AssigneeChevron U.S.A. Inc.
InventorsHaijing Wang, Hanming Wang, Emmanuel Toumelin
Life of this patent
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Abstract
A method for determining water-filled porosity and water salinity in a well includes obtaining complex dielectric permittivity of earth formations, either from dielectric measurements representative of well cores, or from dielectric well logs; selecting a dielectric mixing law for the index number m; plotting a m-th root of complex dielectric permittivity at a specified frequency in the complex domain, wherein m is an index number; determining a matrix permittivity, a water salinity, and a water-filled porosity based on the complex dielectric permittivity and the dielectric mixing law; and displaying the water salinity and the water-filled porosity.
Claims22
A computer-implemented method of determining water-filled porosity and water salinity in a well, the method comprising:
- applying a dielectric apparatus to a well core, the dielectric apparatus comprising a dielectric probe, and a frequency sweep signal generator;
- generating, with the frequency sweep signal generator, a broadband signal over a selected frequency range;
- obtaining, from the dielectric probe, a complex dielectric permittivity of the well core in response to the broadband signal;
- selecting a dielectric mixing law with the index number m;
- calculating m-th root of complex dielectric permittivity over the selected frequency range;
- plotting, on a graphical user interface (GUI), a m-th root of complex dielectric permittivity over the selected frequency range in a complex domain, wherein m is an index number;
- determining, with a porosity and salinity logical circuit, a matrix permittivity, a water salinity, and a water-filled porosity based on the complex dielectric permittivity and the dielectric mixing law, wherein the water salinity is determined further by crossing of a linear regression fit of the m-th root of complex dielectric permittivity with a water line in the complex domain;
- and
- displaying the water salinity and the water-filled porosity on the GUI.
A system for determining water-filled porosity and water salinity in a well, the system comprising:
- a dielectric apparatus comprising a dielectric probe, a frequency sweep signal generator, a porosity and salinity logical circuit, and a graphical user interface;
- wherein the frequency sweep signal generator is configured to generate a broadband signal over a selected frequency range;
- and
- the porosity and salinity logical circuit comprises a processor and a non-transitory medium with computer executable instructions embedded thereon, the computer executable instructions configured to:
- obtain a complex dielectric permittivity from a dielectric probe applied to a well core or from well logs stored in a memory;
- select a dielectric mixing law with the index number m;
- calculate an m-th root of complex dielectric permittivity over the selected frequency range;
- plot, on the graphical user interface (GUI), a m-th root of complex dielectric permittivity over the selected frequency range in a complex domain, wherein m is an index number;
- determine a matrix permittivity, a water salinity, and a water-filled porosity based on the complex dielectric permittivity and the dielectric mixing law, wherein the water salinity is determined further by crossing of a linear regression fit of the m-th root of complex dielectric permittivity with a water line in the complex domain;
- and
- display the water salinity and the water-filled porosity on the GUI.
Dependencies are inferred from the claim text.