Method and system for detection of a material within a region of the earth
First Claim
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1. A method of detecting a first material in the presence of a second material within a region of interest in the Earth comprising:
- transmitting a first inversion radio frequency (RF) excitation signal with at least one coil in the presence of a static magnetic field, the excitation signal sufficient to invert magnetization vectors of both the first and second material in an inversion region within the region of interest such that a plurality of magnetization vectors of the first and second material are substantially aligned with the negative (−
) z axis;
at a point in time when the longitudinal magnetization vector of the second material is substantially zero along the z-axis, transmitting a second RF excitation signal that is a read excitation signal with the at least one coil such that the NMR signal from the second material is selectively suppressed in a detection region a given distance remote from the at least one coil; and
receiving any NMR signal of the first material generated by the second RF excitation signal originating from the detection region.
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Abstract
Methods and systems for detecting a material within a region of the Earth are provided. The region may be under a surface of earthen formation, ice, snow, or water. The method may be practiced in a variety of applications, for example in an arctic region to detect oil spills, leaks, or seepages. The methods and systems may include using at least one coil to transmit a radio frequency (RF) excitation signal into the region of the Earth; and receive any NMR response signals to determine the presence of the material of interest.
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Citations
29 Claims
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1. A method of detecting a first material in the presence of a second material within a region of interest in the Earth comprising:
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transmitting a first inversion radio frequency (RF) excitation signal with at least one coil in the presence of a static magnetic field, the excitation signal sufficient to invert magnetization vectors of both the first and second material in an inversion region within the region of interest such that a plurality of magnetization vectors of the first and second material are substantially aligned with the negative (−
) z axis;at a point in time when the longitudinal magnetization vector of the second material is substantially zero along the z-axis, transmitting a second RF excitation signal that is a read excitation signal with the at least one coil such that the NMR signal from the second material is selectively suppressed in a detection region a given distance remote from the at least one coil; and receiving any NMR signal of the first material generated by the second RF excitation signal originating from the detection region. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. A method of detecting a first material in the presence of a second material within a region of the Earth comprising:
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transmitting a first adiabatic fast passage inversion sweep with at least one coil in the presence of a static magnetic field, the sweep sufficient to invert magnetization vectors of both the first and second material in an inversion region such that the magnetization vectors of the first and second material are substantially aligned with the negative (−
) z axis;at a point in time when the longitudinal magnetization vector of the second material is substantially zero along the z-axis, transmitting a second RF excitation signal that is a read excitation signal with the at least one coil such that the NMR signal from the second material is selectively suppressed in a detection region a given distance remote from the at least one coil; and receiving any NMR signal of the first material generated by the second RF excitation signal originating from the detection region, wherein the static magnetic field is Earth'"'"'s magnetic field. - View Dependent Claims (25, 26, 27)
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28. A system for detecting a material within a region of interest in the Earth comprising:
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at least one coil positioned proximate to the region; a transmitter operatively connected to the at least one coil; a receiver operatively connected to the at least one coil; and at least one switch configured to provide a broadband signal response in the at least one coil at a transmitting Q factor when transmitting an adiabatic fast passage excitation signal and to receive a NMR signal response in a narrow band at a greater Q factor compared to the transmitting Q factor. - View Dependent Claims (29)
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Specification