Method And Apparatus For Detection of A Liquid Under A Surface

• US 20110181279A1
• Filed: 08/29/2008
• Published: 07/28/2011
• Est. Priority Date: 10/05/2007
• Status: Active Grant

• Current Assignee: Exxonmobil Upstream Research Company (Exxon Mobil Corporation)
• Original Assignee: Exxonmobil Upstream Research Company (Exxon Mobil Corporation)
• Inventors: Thomann, Hans, Sandstrom, Robert E., Srnka, Leonard J., Nedwed, Timothy J.
• Granted Patent: US 8,436,609 B2
• Time in Patent Office: Days
• US Class Current: 324/307
• CPC Class Codes: G01N 24/08 by using nuclear magnetic resonance G01N24/12 takes precedence
• CPC Class Codes: G01N 24/081 Making measurements of geologic samples, e.g. measurements of moisture, pH, porosity, permeability, tortuosity or viscosity
• CPC Class Codes: G01R 33/50 based on the determination of relaxation times , e.g. T1 measurement by IR sequences; T2 measurement by multiple-echo sequences
• CPC Class Codes: G01V 3/175 operating with electron or nuclear magnetic resonance
• CPC Class Codes: Y02A 90/30 Assessment of water resources
• CPC Class Codes: Y02A 90/344 by measuring magnetic field strength

Abstract

Methods for detecting a liquid under a surface and characterizing Ice are provided The liquid may be a liquid hydrocarbon such as crude oil or fuel oil or mineral oil The surface may be ice, snow, or water, and the method may be practiced in an arctic region to detect oil spills, leaks, or seepages The methods may be used with a range finder to characterize marine ice The methods may include a nuclear magnetic resonance (NMR) tool with antenna to send a radio-frequency (RF) excitation pulse or signal into volume of substances being detected, detect an NMR response signal to determine the presence of the liquid of interest The NMR response may include a relaxation time element and an intensity level and may include a free induction signal (T2*), a spin echo signal (T2), a train of spin echo signals (T2), or a thermal equilibrium signal (T 1).

Claims

1. A method for detecting a liquid under a surface, comprising:

a) locating a volume of substances under the surface, wherein at least a portion of the volume of substances is within a static magnetic field;

b) transmitting at least one radio-frequency excitation pulse from a remote location above the volume of substances to generate a nuclear magnetic resonance (NMR) signal from the volume of substances;

c) detecting, from the remote location, the NMR signal from the volume of substances; and

d) processing the detected NMR signal to determine whether the volume of substances includes the liquid.

2. The method of claim 1, wherein the surface is snow or ice and the ice is selected from the group consisting of marine ice, freshwater ice, land-fast ice, moving ice, first year ice, multiyear ice, pack ice, and any combination thereof.

3. The method of claim 1, wherein the liquid is selected from the group consisting of a hydrocarbon crude oil, vegetable oil, mineral oil, fuel oil, and any combination thereof.

4. The method of claim 1, wherein processing the detected nuclear magnetic resonance (NMR) signal comprises interpreting data selected from the group consisting of the intensity of the NMR signal, the relaxation time of the NMR signal, and any combination thereof.

5. The method of claim 4, wherein the relaxation time of the NMR signal is selected from the group consisting of a free induction signal (T2*), a spin echo signal (T2), a train of spin echo signals (T2), a thermal equilibrium signal (T1), and any combination thereof.

6. The method of claim 4, wherein the remote location is an airborne platform positioned substantially vertically above the volume of substances to be detected.

7. The method of claim 6, wherein the airborne platform is one of a helicopter and a lighter-than-air vehicle.

8. The method of claim 4, wherein the static magnetic field is one of the Earth'"'"'s natural magnetic field and a magnetic field generated by a man-made device.

9. The method of claim 4, wherein the remote location is from less than one meter above the surface to about ten meters above the surface.

10. The method of claim 4, further comprising moving the remote location to another volume of substances and repeating steps b) through d) for the another volume of substances.

11. The method of claim 10, wherein the another volume of substances is in an area of interest in an ice-prone region.

12. The method of claim 11, wherein the method is continuous throughout the area of interest and steps b) through d) are repeated until one of:

i) the liquid is detected under the surface in the area of interest;

ii) the liquid is mapped under the surface in the area of interest;

or iii) it is determined that the liquid is not present under the surface in the area of interest.

13. The method of claim 11, wherein the method is iterative throughout the area of interest and steps b) through d) are repeated until sufficient data is gathered to map the presence of the liquid in the area of interest.

14. The method of claim 4, wherein at least steps b) and c) are conducted using a nuclear magnetic resonance (NMR) tool, wherein the NMR tool comprises a conductive wire loop configured to at least transmit the at least one radio-frequency excitation pulse and to detect the at least one NMR signal from the volume of substances.

15. The method of claim 14, wherein the conductive wire loop has a largest dimension, wherein the largest dimension is from at least about five meters to about twenty meters.

16. The method of claim 11, wherein the area of interest is selected from the group consisting of an offshore arctic or sub-arctic area for detection of an oil spill for the purpose of oil spill remediation, an offshore or onshore arctic or sub-arctic area for detection of an oil seep for the purpose of hydrocarbon exploration, and an onshore arctic or sub-arctic area for detection of oil leaks from man-made structures for the purposes of remediation and repair of the structures.

27. The apparatus of claim 25, wherein the apparatus is configured to function in accordance with the method of claim 1.

17. A method of mapping the presence of a liquid under a surface, comprising:

selecting an area of interest having a surface at least partially obscuring visual detection of substances below the surface;

traversing the area of interest while using a detection method to gather data regarding the presence of the liquid under the surface, wherein a nuclear magnetic resonance (NMR) tool is used to conduct at least a portion of the detection method; and

mapping the presence of the liquid under the surface using the gathered data.

18. The method of claim 17, wherein the detection method comprises:

a) locating a volume of substances under a surface in the area of interest, wherein at least a portion of the volume of substances is within a static magnetic field;

b) transmitting at least one radio-frequency excitation pulse from a remote location above the volume of substances to generate a nuclear magnetic resonance (NMR) signal from the volume of substances;

c) detecting, from the remote location, the NMR signal from the volume of substances; and

d) processing the detected NMR signal to determine whether the volume of substances includes the liquid.

19. The method of claim 18, wherein the surface is water, snow, or ice and the ice is selected from the group consisting of marine ice, freshwater ice, land-fast ice, moving ice, first year ice, multiyear ice, pack ice and any combination thereof.

20. The method of claim 18, wherein the liquid is selected from the group consisting of a hydrocarbon crude oil, vegetable oil, mineral oil, fuel oil, and any combination thereof.

21. The method of claim 18, wherein processing the detected nuclear magnetic resonance (NMR) signal comprises interpreting at least one of the intensity of the NMR signal and the relaxation time of the NMR signal, wherein the relaxation time of the NMR signal is selected from the group consisting of a free induction signal (T2*), a spin echo signal (T2), a train of spin echo signals (T2), a thermal equilibrium signal (T1), and any combination thereof.

22. The method of claim 17, further comprising planning a route within the area of interest.

23. The method of claim 18, wherein the detection method is selected from the group consisting of:

i) continuous throughout the area of interest ii) iterative throughout the area of interest, and any combination thereof.

24. The method of claim 18, wherein the area of interest is selected from the group consisting of an offshore arctic or sub-arctic area for detection of an oil spill for the purpose of oil spill remediation, an offshore or onshore arctic or sub-arctic area for detection of an oil seep for the purpose of hydrocarbon exploration, and an onshore arctic or sub-arctic area for detection of oil leaks from man-made structures for the purposes of remediation and repair of the structures.

25. An apparatus for detecting a liquid hydrocarbon under a surface, comprising:

a nuclear magnetic resonance (NMR) tool having an antenna for sending and receiving signals mounted to an airborne platform and configured to receive the NMR tool and the antenna, wherein the antenna is a wire loop having a largest dimension of from about five meters to less than about twenty meters.

26. The apparatus of claim 25, wherein the wire loop is constructed from one of copper tubing, copper wire, aluminum tubing, and aluminum wire.

28. A method of characterizing ice, comprising:

a) locating, from a remote location, an air/surface interface within a volume of interest in a static magnetic field, wherein the surface is an upper ice surface;

b) locating a liquid/surface interface within the volume of interest, wherein the surface is a lower ice surface, comprising;

1) transmitting at least one radio-frequency excitation pulse from the remote location above the volume of interest to generate a nuclear magnetic resonance (NMR) signal from the volume of interest;

2) detecting, from the remote location, the NMR signal from the volume of interest; and

3) processing the detected NMR signal to determine the location of the liquid/surface interface within the volume of interest; and

c) determining the thickness of a body of ice in the volume of interest by calculating a distance between the air/surface interface and the liquid/surface interface.

29. The method of claim 28, wherein the air/surface interface is detected using a device selected from the group consisting of a laser, an altimeter, radar, an elongated member, and any combination thereof.

30. The method of claim 28, further comprising determining the type of ice of the body of ice utilizing the detected NMR signal, wherein the type of ice is selected from the group consisting of marine ice, freshwater ice, land-fast ice, moving ice, first year ice, multiyear ice, and pack ice.

31. The method of claim 28, further comprising:

locating a volume of substances under the liquid/surface interface, wherein at least a portion of the volume of substances is within the static magnetic field; and

processing the detected NMR signal to determine whether the volume of substances includes a liquid selected from the group consisting of a hydrocarbon crude oil, vegetable oil, mineral oil, fuel oil, and any combination thereof.