Nuclear magnetic resonance apparatus and methods for analyzing fluids extracted from earth formation
First Claim
1. A method of making a nuclear magnetic resonance measurement on a flowing fluid comprising:
- a) flowing the fluid through a static magnetic field;
b) applying a group of oscillating magnetic field pulses to the flowing fluid, wherein each group of pulses is comprised of an initial pulse and one or more refocusing pulses, and wherein the group of pulses further comprise a spoiler rf pulse;
c) detecting magnetic resonance signals from the flowing fluid;
d) after a wait time, repeating (b) and (c) one or more times, wherein at least two of the repetitions have varied wait times; and
e) analyzing the detected magnetic resonance signals to extract information about the flowing fluid.
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Abstract
The present invention discloses a method and apparatus to make a nuclear magnetic resonance measurement on a flowing fluid using varied wait times. In one method, NMR measurements are made by: a) flowing the fluid through a static magnetic field; b) applying a group of oscillating magnetic field pulses to the flowing fluid, wherein the group of pulses is comprised of an initial pulse and one or more refocusing pulses; c) detecting magnetic resonance signals from the flowing fluid; d) after a wait time, repeating (b) and (c) one or more times, wherein at least two of the repetitions have varied wait times; and e) analyzing the detected magnetic resonance signals to extract information about the flowing fluid. Further, varied wait time measurements may be useful in determining the flow rate of the sample.
55 Citations
28 Claims
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1. A method of making a nuclear magnetic resonance measurement on a flowing fluid comprising:
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a) flowing the fluid through a static magnetic field;
b) applying a group of oscillating magnetic field pulses to the flowing fluid, wherein each group of pulses is comprised of an initial pulse and one or more refocusing pulses, and wherein the group of pulses further comprise a spoiler rf pulse;
c) detecting magnetic resonance signals from the flowing fluid;
d) after a wait time, repeating (b) and (c) one or more times, wherein at least two of the repetitions have varied wait times; and
e) analyzing the detected magnetic resonance signals to extract information about the flowing fluid. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A method of analyzing a fluid in a downhole environment comprising:
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a) introducing a fluid sampling tool into a well bore that traverses an earth formation;
b) using the fluid sampling tool to extract the fluid from the earth formation into a flow channel within the tool;
c) flowing the fluid through a static magnetic field;
d) applying one or more groups of oscillating magnetic field pulses to the fluid in the flow channel, wherein the group of pulses comprises an initial pulse followed by one or more refocusing pulses, wherein at least two groups of pulses are generated after a varied wait time, and wherein the group of pulses further comprise a spoiler rf pulse;
e) detecting from the flowing fluid magnetic resonance signals within each group of pulses; and
f) analyzing the detected signals to extract information about the flowing fluid. - View Dependent Claims (20)
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21. An apparatus for analyzing a fluid in a downhole environment comprising:
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a) means for extracting the fluid from an earth formation into a flow channel within a well logging tool;
b) means for generating a static magnetic field within the flow channel;
c) means for generating one or more groups of oscillating magnetic field pulses to the fluid in the flow channel, wherein each group of pulses is comprised of an initial pulse followed by one or more refocusing pulses, wherein at least two groups of pulses are generated after a varied wait time, and wherein the group of pulses further comprise a spoiler rf pulse;
d) means for detecting magnetic resonance signals; and
e) means for analyzing the detected magnetic resonance signals. - View Dependent Claims (22, 23, 24, 25, 26, 27)
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28. A method of making a nuclear magnetic resonance measurement on a flowing fluid comprising:
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a) flowing the fluid through a static magnetic field, wherein the static magnetic field includes a magnetic field gradient;
b) applying a group of oscillating magnetic field pulses to the flowing fluid, wherein each group of pulses is comprised of an initial pulse and one or more refocusing pulses;
c) detecting magnetic resonance signals from the flowing fluid;
d) after a wait time, repeating (b) and (c) one or more times, wherein at least two of the repetitions have varied wait times; and
e) analyzing the detected magnetic resonance signals to measure the flow rate of the flowing fluid by monitoring the magnetic resonance signals for a change in frequency between wait times.
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Specification