Method for identifying chemical species in a substance using NQR

Patent metadata

Field	Value
Publication number	US-10088540-B2
Application number	US-201414888732-A
Country	US
Kind code	B2
Filing date	May 1, 2014
Priority date	May 3, 2013
Publication date	Oct 2, 2018
Grant date	Oct 2, 2018

Abstract

Methods and systems for identifying a chemical species within a substance using nuclear quadrupole resonance (NQR) are described herein. One method includes applying a number of NQR perturbation-detection pulse sequences to the substance. Each perturbation-detection pulse sequence includes a perturbation segment applied at a perturbation frequency and a detection segment applied at a second different frequency. As the sequences are applied, the perturbation frequency, the second frequency, or both are varied for each pulse sequence. The method also includes applying a number of NQR reference pulse sequences to the substance at a reference frequency. The reference frequency is varied for each pulse sequence. A chemical species is identified within the substance by comparing (i) a set of NQR signals generated by the perturbation-detection pulse sequences with (ii) a reference set of NQR signals generated by the reference pulse sequences.

First claim

We claim:

1. A method for identifying chemical species within a substance using nuclear quadrupole resonance (NQR), the method comprising:
applying a plurality of NQR perturbation-detection pulse sequences to the substance, wherein each perturbation-detection pulse sequence includes:
a perturbation segment at a perturbation frequency; and
a detection segment at a second frequency, wherein at least one of the perturbation frequency and the second frequency are varied for each pulse sequence and the perturbation frequency and second frequency are different frequencies;

detecting a perturbation-detection set of NQR signals generated within the substance by each of the perturbation-detection pulse sequences;
applying a plurality of NQR reference pulse sequences to the substance, wherein each reference pulse sequence is applied at a reference frequency and the reference frequency is varied for each pulse sequence;
detecting a reference set of NQR signals generated within the substance by each of the reference pulse sequences; and
identifying a chemical species within the substance by comparing the perturbation-detection set of NQR signals and the reference set of NQR signals.

2. The method of claim 1 , wherein identifying the chemical species within the substance comprises:
using the set of perturbation-detection NQR signals to generate a two-dimensional spectrum of the perturbation frequency and the second frequency;
using the reference set of NQR signals to generate a reference spectrum for the reference frequency; and
comparing the two-dimensional spectrum to the reference spectrum to identify the chemical species within the substance.

3. The method of claim 2 , wherein the comparing the two-dimensional spectrum to the reference spectrum comprises:
generating a difference spectrum using the two-dimensional spectrum and the reference spectrum; and
identifying peaks within the difference spectrum.

4. The method of claim 2 , wherein the second frequency is varied over a set of different frequencies and the reference frequency is varied over the same set of different frequencies.

5. The method of claim 2 , wherein the second frequency is varied a plurality of times for each perturbation frequency.

6. The method of claim 2 , wherein the plurality of reference pulse sequences are applied to the substance before the plurality of perturbation-detection pulse sequences are applied to the substance.

7. The method of claim 6 , further comprising:
identifying a plurality of peaks within the reference spectrum generated by the reference set of NQR signals; and
selecting the perturbation frequency and the second frequency in the plurality of NQR perturbation-detection pulse sequences using frequencies associated with the identified peaks in the reference spectrum.

8. The method of claim 7 , wherein the chemical species is selected from the group consisting of: Glycine, Proline, Ammonium Nitrate, TNT, RDX, Cocaine Hydrochloride, and Heroin Hydrochloride.

9. The method of claim 1 , wherein the chemical species is a chemical compound that includes atomic nuclei selected from the group consisting of: nitrogen, chlorine, potassium, and copper.

10. The method of claim 1 , wherein at least one NQR perturbation-detection pulse sequence of the plurality of perturbation-detection pulse sequences is at least partially interposed within another perturbation-detection pulse sequence.

11. The method of claim 1 , wherein each NQR pulse sequence is applied to the substance using a coil and a NQR transmitter comprising a non-resonant NQR transmitter circuit electronically coupled to the coil.

12. A system comprising:
at least one coil for applying a nuclear quadrupole resonance (NQR) pulse sequences to a substance and for detecting NQR signals generated within the substance;
a NQR transmitter electronically coupled to the at least one coil and configured to generate and transmit NQR pulses sequences to the coil;
a NQR receiver coupled to the at least one coil and configured to process detected NQR signals;
a processor; and
a memory storing instructions executable by the processor to perform processes that include:
providing a plurality of NQR perturbation-detection pulse sequences to the NQR transmitter, wherein each perturbation-detection pulse sequence includes:
a perturbation segment at a perturbation frequency; and
a detection segment at a second frequency, wherein at least one of the perturbation frequency and the second frequency are varied for each pulse sequence and the perturbation frequency and second frequencies are different frequencies;

providing a plurality of NQR reference pulse sequences to the NQR transmitter, wherein each reference pulse sequence is applied at a reference frequency and the reference frequency is varied for each pulse sequence;
receiving from the NQR transmitter (i) a perturbation-detection set of NQR signals generated within the substance by each of the perturbation-detection pulse sequences and (ii) a reference set of NQR signals generated within the substance by each of the reference pulse sequences; and
identifying a chemical species within the substance by comparing the perturbation-detection set of NQR signals and the reference set of NQR signals.

13. The system of claim 12 , wherein the NQR transmitter comprises a non-resonant NQR transmitter circuit.

14. The system of claim 12 , wherein the system comprises an explosive detection system.

15. The system of claim 12 , wherein the system comprises a drug detection system.

16. The system of claim 12 , wherein the system comprises a wellbore logging system.

17. The system of claim 12 , wherein the memory stores instructions executable by the processor to perform processes that further include:
using the set of perturbation-detection NQR signals to generate a two-dimensional spectrum of the perturbation frequency versus the second frequency;
using the reference set of NQR signals to generate a reference spectrum for the reference frequency; and
comparing the two-dimensional spectrum to the reference spectrum to identify the chemical species within the substance.

18. The system of claim 17 , wherein the memory stores instructions executable by the processor to perform processes that further include:
generating a difference spectrum using the two-dimensional spectrum and the reference spectrum; and
identifying peaks within the difference spectrum.

19. The system of claim 17 , wherein the memory stores instructions executable by the processor to perform processes that further include:
identifying a plurality of peaks within the reference spectrum generated by the reference set of NQR signals; and
selecting the perturbation frequency and second frequency in the plurality of NQR perturbation-detection pulse sequences using frequencies associated with the identified peaks in the reference spectrum.

20. The system of claim 12 , wherein the second frequency is varied over a plurality of different frequencies and the reference frequency is varied over the same plurality of different frequencies.

Assignees

• Schlumberger Technology Corp

Inventors

• Song Yi-Qiao
• Mandal Soumyajit

Classifications

• G01N24/084

  Detection of potentially hazardous samples, e.g. toxic samples, explosives, drugs, firearms, weapons · CPC title

• G01N24/081

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

• G01R33/441 Primary

  Nuclear Quadrupole Resonance [NQR] Spectroscopy and Imaging · CPC title