Methods and systems for detecting RFID tags in a borehole environment
First Claim
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1. A method of detecting radio frequency identification device (RFID) tags in a borehole, comprising:
- scanning for the RFID tags at a plurality of frequencies in at least a portion of an annulus surrounding an exterior of a casing string in the borehole, wherein the RFID tags are embedded in a wellbore composition within the annulus;
receiving a plurality of corresponding results from the RFID tags, wherein each corresponding result of the plurality of corresponding results corresponds to a different one of the plurality of frequencies;
comparing the plurality of corresponding results to one another, wherein the comparing of the plurality of corresponding results comprises digitizing the plurality of corresponding results at a rate faster than a sweep time of said each of the plurality of corresponding results to create digitized signals, andwherein the comparing of the plurality of corresponding results comprises performing background correction by comparing the digitized signals of multiple sweeps to provide a background corrected signal; and
determining whether one or more of the RFID tags are present in the portion of the annulus based on the comparing of the plurality of corresponding results.
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Abstract
Sensor assemblies are deployed in a borehole for a well, such as an oil well or other hydrocarbon recovery well. The sensor assemblies may be coupled to a casing string (e.g., the exterior of the casing), and detect RFID tags or other properties of material (e.g., fluids) in an annulus surrounding the casing string. During cementing or other operations, RFID tags may be used to track fluids. RFID detection circuits may be used to scan at different frequencies, and corresponding results may be compared by various means and processes to determine the presence of RFID tags.
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Citations
27 Claims
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1. A method of detecting radio frequency identification device (RFID) tags in a borehole, comprising:
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scanning for the RFID tags at a plurality of frequencies in at least a portion of an annulus surrounding an exterior of a casing string in the borehole, wherein the RFID tags are embedded in a wellbore composition within the annulus; receiving a plurality of corresponding results from the RFID tags, wherein each corresponding result of the plurality of corresponding results corresponds to a different one of the plurality of frequencies; comparing the plurality of corresponding results to one another, wherein the comparing of the plurality of corresponding results comprises digitizing the plurality of corresponding results at a rate faster than a sweep time of said each of the plurality of corresponding results to create digitized signals, and wherein the comparing of the plurality of corresponding results comprises performing background correction by comparing the digitized signals of multiple sweeps to provide a background corrected signal; and
determining whether one or more of the RFID tags are present in the portion of the annulus based on the comparing of the plurality of corresponding results. - 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 detecting radio frequency identification device (RFID) tags in a borehole, comprising:
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scanning for the RFID tags, at first, second, and third frequencies, in at least a portion of an annulus surrounding an exterior of a casing string in the borehole, wherein the RFID tags are embedded in a wellbore composition within the annulus; receiving first, second, and third results from the RFID tags for the first, second, and third frequencies; generating result comparisons, wherein said generating the result comparisons comprise comparing the first result with the second result, and the second result with the third result, and wherein said generating the result comparisons comprises digitizing each of the first result second result and third result at a rate faster than a sweep time corresponding to said each of the first result, second result and third result to create digitized signals, and wherein said generating the result comparisons comprises performing background correction by comparing the digitized signals of multiple sweeps to provide a background corrected signal; and based on the result comparisons, determining whether one or more of the RFID tags are present in the portion of the annulus. - View Dependent Claims (20, 21, 22)
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23. A downhole assembly, comprising:
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a radio frequency identification device (RFID) detection circuit to operate while the downhole assembly is coupled to a casing string, and to scan for RFID tags at a plurality of frequencies in at least a portion of an annulus surrounding the casing string in a borehole, the scanning for the RFID tags including receiving a corresponding scan result for each of the plurality of frequencies, wherein the RFID tags are embedded in a wellbore composition within the annulus; an analog monitoring circuit to measure a voltage across a resistor in the RFID detection circuit, the voltage indicating a level of power reflected from the portion of the annulus during the scanning at the plurality of frequencies; and a digital comparator circuit to;
convert an analog value to a digital value at a rate faster than a corresponding sweep time of the analog value, the analog value corresponding to a voltage difference between two voltage measurements taken by the analog monitoring circuit;performing background correction on the digital value by comparing the digital value to a plurality of digitized signals of multiple sweeps to provide a background corrected signal; and determine whether one or more of the RFID tags are present in the portion of the annulus by determining whether the digital value exceeds a threshold value. - View Dependent Claims (24, 25, 26, 27)
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Specification