Cancellation of vibration noise in deep transient resistivity measurements while drilling
First Claim
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1. A method of evaluating an earth formation, the method comprising:
- using a transmitter on a carrier conveyed in a borehole for producing an electromagnetic signal in the earth formation;
using at least one antenna on the carrier for producing a first signal responsive to an interaction of the electromagnetic signal with the earth formation, the first signal including a noise resulting from a vibration of the carrier;
correcting the first signal for the noise and producing a corrected first signal using a second signal indicative of the vibration of the carrier;
estimating a distance to an interface in the earth formation using the corrected first signal; and
conducting further operations using the estimated distance.
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Abstract
A transient electromagnetic (TEM) signal is recorded in an earth formation during vibration of a logging tool. Concurrently, accelerometer measurements are made. The accelerometer measurements are used to correct the TEM signal for the vibration using the accelerometer measurement and a transfer function relating the TEM signal and the accelerometer. The transfer function may be determined using measurements in a water tank or by using the tail end of the TEM measurements.
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Citations
18 Claims
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1. A method of evaluating an earth formation, the method comprising:
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using a transmitter on a carrier conveyed in a borehole for producing an electromagnetic signal in the earth formation; using at least one antenna on the carrier for producing a first signal responsive to an interaction of the electromagnetic signal with the earth formation, the first signal including a noise resulting from a vibration of the carrier; correcting the first signal for the noise and producing a corrected first signal using a second signal indicative of the vibration of the carrier; estimating a distance to an interface in the earth formation using the corrected first signal; and conducting further operations using the estimated distance. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. An apparatus configured to evaluate an earth formation the apparatus comprising:
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a carrier configured to be conveyed in a borehole; a transmitter on the carrier configured to produce an electromagnetic signal in the earth formation; at least one antenna on the carrier configured to produce a first signal responsive to an interaction of the electromagnetic signal with the earth formation, the first signal including a noise resulting from a vibration of the carrier; at least one accelerometer on the carrier configured to produce at least one second signal indicative of the vibration of the carrier; and at least one processor configured to; (a) produce a corrected first signal using the first signal and the at least one second signal; (b) estimate a distance to an interface in the earth formation using the corrected first signal; and (c) conduct further operations using the estimated distance. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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17. A computer-readable medium product having stored thereon instructions that when read by at least one processor cause the at least one processor to execute a method, the method comprising:
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correcting a first signal received by at least one antenna on a carrier conveyed in a borehole responsive to an electromagnetic signal produced by a transmitter on the carrier for an effect of a vibration of the carrier using a measurement made by an accelerometer on the carrier; using the corrected first signal to estimate a distance to an interface in the earth formation; and conducting further operations using the estimated distance. - View Dependent Claims (18)
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Specification