Magnetic resonance method for characterizing fluid samples withdrawn from subsurface earth formations
First Claim
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1. A method of analyzing fluid in a downhole environment comprising:
- 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) monitoring an indication of contamination in the fluid while extracting the fluid from the earth formation and flowing the fluid through the flow channel; and
d) when the indication of contamination in the fluid has stabilized, analyzing the fluid in the flow channel.
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Abstract
Nuclear magnetic resonance techniques are used in a fluid sampling tool that extracts a fluid from subsurface earth formations into a flow channel within the tool. The magnetic resonance techniques involve applying a static magnetic field and an oscillating magnetic field to the fluid in the flow channel, and magnetic resonance signals are detected from the fluid and analyzed to extract information about the fluid such as composition, viscosity, etc.
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Citations
29 Claims
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1. A method of analyzing 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) monitoring an indication of contamination in the fluid while extracting the fluid from the earth formation and flowing the fluid through the flow channel; and
d) when the indication of contamination in the fluid has stabilized, analyzing the fluid in the flow channel. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method of analyzing hydrocarbon in 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 fluid from the earth formation into a flow channel within the tool;
c) applying a static magnetic field to the fluid in the flow channel;
d) applying an oscillating magnetic field at a frequency sensitive to carbon-13 nuclei to the fluid in the flow channel;
e) detecting magnetic resonance signals indicative of carbon-13 nuclei from the fluid; and
f) analyzing the detected magnetic resonance signals to extract information about hydrocarbon in the fluid. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 18, 19, 20)
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17. A method of analyzing water phase 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 fluid from the earth formation into a flow channel within the tool;
c) applying a static magnetic field to the fluid in the flow channel;
d) applying an oscillating magnetic field to the fluid in the flow channel;
e) detecting magnetic resonance signals indicative of nuclei of at least one of the following from the fluid;
sodium-23, chlorine-35, chlorine-37, and potassium-39; and
f) analyzing the detected magnetic resonance signals to determine information about the water phase fluid.
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21. A method of determining stock tank API gravity of a crude oil sample from downhole fluid analysis 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 crude oil sample from the earth formation;
c) measuring a downhole temperature of the crude oil sample;
d) determining a downhole viscosity of the crude oil sample;
e) determining a downhole gas/oil ratio of the crude oil sample; and
f) correlating the dowhole temperature, viscosity and gas/oil ratio with the stock tank API gravity of the crude oil sample. - View Dependent Claims (22, 23, 24, 25, 27, 28, 29)
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26. A nuclear magnetic resonance module adapted for incorporation into a fluid sampling tool comprising:
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a permanent magnet array adapted to be arranged around a flow line in the fluid sampling tool;
a nuclear magnetic resonance antenna adapted to be arranged around the flow line;
means coupled with the antenna for generating an oscillating magnetic field within the flow line; and
means coupled with the antenna for detecting nuclear magnetic resonance signals from the flow line.
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Specification