System and method for measuring velocity profiles

Patent metadata

Field	Value
Publication number	US-10655996-B2
Application number	US-201715484665-A
Country	US
Kind code	B2
Filing date	Apr 11, 2017
Priority date	Apr 12, 2016
Publication date	May 19, 2020
Grant date	May 19, 2020

Abstract

Method of determining a velocity profile of a fluid flowing through a conduit, the method including applying a saturation pulse on spins of magnetic field-sensitive nuclei in the fluid, measuring a signal of the fluid to determine position of the magnetic field-sensitive nuclei, the measurement carried out at a recovery time ‘TR’ and at a distance ‘d’ within the conduit, determining within the conduit a radial distance ‘r’ characterized by a local minimum in the measured signal, wherein the radial distance ‘r’ is measured from the center of the conduit, and determining a velocity profile of the fluid at the radial distance, based on the magnetic field-sensitive nuclei.

First claim

The invention claimed is:

1. A method of determining a velocity profile of a fluid flowing through a conduit, the method comprising:
applying a saturation pulse on spins of magnetic field-sensitive nuclei in the fluid;
measuring a signal of the fluid to determine position of the magnetic field-sensitive nuclei, the measurement carried out at a recovery time ‘TR’ and at a distance within the conduit;
determining within the conduit a radial distance ‘r’ characterized by a local minimum in the measured signal, wherein the radial distance ‘r’ is measured from the center of the conduit; and
determining a velocity profile of the fluid at the radial distance, based on the magnetic field-sensitive nuclei.

2. The method according to claim 1 , the position of the local minimum in the signal corresponds to the local flow velocity.

3. The method according to claim 1 , wherein applying a saturation pulse is carried out for a tagging slice of the fluid located at a predetermined position along said flow.

4. The method according to claim 2 , wherein the measurement is carried out for a corresponding readout slice of the fluid, and wherein the readout slice is at a predetermined distance from the tagging slice.

5. The method according to claim 1 , comprising encoding the velocity in a direction parallel to the flow of the fluid within the conduit.

6. The method according to claim 5 , further comprising:
encoding the velocity in a direction perpendicular to the flow of the fluid within the conduit; and
comparing the measured velocity in both directions to determine the velocity profile.

7. The method according to claim 1 , comprising measuring the intensity of the signal as a function of position.

8. The method according to claim 1 , wherein the measurement is carried out for low flow regions near the wall of the conduit.

9. The method according to claim 1 , further comprising:
varying the value of ‘d’; and
determining a velocity profile v(r) as a function of radial distance ‘r’.

10. The method according to claim 1 , wherein the saturation pulse on spins is a Spin Echo pulse sequence.

11. The method according to claim 1 , wherein the saturation pulse sequence is an echo time ‘TE’ sequence.

12. The method according to claim 1 , wherein the saturation pulse is characterized by a flip angle >90° selected such that the local minimum in said signal is equal to zero.

13. The method according to claim 1 , wherein the fluid comprises drilling mud.

14. A method of determining a velocity profile of a fluid flowing through a conduit, the method comprising:
measuring a signal of the fluid to determine position of magnetic field-sensitive nuclei in the fluid;
normalizing the signal;
applying a saturation pulse on spins of magnetic field-sensitive nuclei in the fluid;
measuring a normalized signal of the fluid, carried out at a recovery time ‘TR’ and at a distance within the conduit;
determining within the conduit a radial distance ‘r’ characterized by a local minimum in the normalized signal, wherein the radial distance ‘r’ is measured from the center of the conduit; and
determining a velocity profile of the fluid at the radial distance, based on the magnetic field-sensitive nuclei.

Assignees

• Aspect Imaging Ltd

Inventors

• Bendel Peter
• Shapira Boaz

Classifications

• G01N24/081

  Making measurements of geologic samples, e.g. measurements of moisture, pH, porosity, permeability, tortuosity or viscosity · CPC title

• G01F1/716 Primary

  using electron paramagnetic resonance [EPR] or nuclear magnetic resonance [NMR] · CPC title

• G01R33/4838

  using spatially selective suppression or saturation of MR signals · CPC title

• G01R33/56308

  Characterization of motion or flow; Dynamic imaging · CPC title