Claims Analysis
Total Claims: 26
Claim 1
Independent Claim
191 words
A method of vertical seismic profiling of earth formations in which a bore hole is drilled through the formation by a drill bit, which acts as a continuous, time-extended, non-impulsive source of acoustic energy comprising the steps of: gathering data from seismic traces with a plurality of receivers forming an array on the earth surface; performing velocity analysis on the seismic traces to obtain a velocity of the earth formation between the drill bit and the receivers and to apply movement corrections to each of the traces gathered by the plurality of receivers; constructing a downward continuation filter for the seismic traces to obtain an estimate of the source drill bit signature by determining a spatial average of the moveout-connected traces, thereby obtaining an estimate of the source drill bit signature; and extracting the source drill bit signature from the seismic traces using the downward continuation filter where the spatial average of the moveout-corrected traces follows the form: ##EQU6## where, N is the total number of traces, S m (W) are the downgoing waves in earth formation between the receivers and the reflecting interface, and t m is the moveout time.
Claim 2
Independent Claim
191 words
A method of vertical seismic profiling of earth formations in which a bore hole is drilled through the formation by a drill bit, which acts as a continuous, time-extended, non-impulsive source of acoustic energy comprising the steps of: gathering data from seismic traces with a plurality of receivers forming an array on the earth surface; performing velocity analysis on the seismic traces to obtain a velocity of the earth formation between the drill bit and the receivers and to apply movement corrections to each of the traces gathered by the plurality of receivers; constructing a downward continuation filter for the seismic traces to obtain an estimate of the source drill bit signature by determining a spatial average of the moveout-connected traces, thereby obtaining an estimate of the source drill bit signature; and extracting the source drill bit signature from the seismic traces using the downward continuation filter where the spatial average of the moveout-corrected traces follows the form: ##EQU6## where, N is the total number of traces, S m (W) are the downgoing waves in earth formation between the receivers and the reflecting interface, and t m is the moveout time.
Claim 3
Dependent Claim
39 words
The method recited in claim 1 further comprising the step of deconvolving the estimate of the drill bit signature by a filter to transform the seismic traces to a data set resembling a walkaway vertical seismic profiling data set.
Claim 4
Dependent Claim
47 words
The method recited in claim 2 wherein the filter which deconvolves the estimate of the drill bit signature follows the form: ##EQU7## where f(ω) is the complex conjugate of f(ω), ##EQU8## is the inverse amplitude of f(ω), and D(ω) is a signature of the source drill bit.
Claim 5
Dependent Claim
48 words
The method recited in claim 3 wherein the signature of the source drill bit follows the form: D(ω)=e.sup.iωt m, where, t m is the time it takes an acoustic wave to travel from a position of the drill bit in the earth to the receivers in the array.
Claim 6
Dependent Claim
32 words
The method recited in claim 4 wherein the receivers are positioned in the array with a breadth and length substantially the same as the depth of the drill bit in the earth.
Claim 7
Dependent Claim
23 words
The method recited in claim 5 wherein the receivers in the array are arranged in a substantially rectangular pattern of rows and columns.
Claim 8
Independent Claim
219 words
A method for obtaining vertical seismic profiles of an earth formation in which there is located an acoustic wave source having a time-extended, non-impulsive signature, comprising the steps of: (a) providing an array of acoustic wave receivers spaced apart over the earth's surface to produce from said receivers, in response to acoustic waves from said source, a group of seismic waveforms; (b) determining an acoustic velocity of the earth formation between the acoustic wave source and the receivers in the array; (c) applying moveout correction to said group of seismic waveforms to compensate for the differences in the travel time of said seismic waveforms from said source to said receivers; (d) applying to said seismic waveforms a downward continuation filter to focus the array on the location of said source by determining a spatial average of the moveout-corrected seismic waveforms, thereby obtaining an estimate of the acoustic wave source signature; and (e) extracting said acoustic wave source signature from said focused, moveout-corrected seismic data sets to produce seismic profiles of the earth formation "wherein the spatial average of the moveout-corrected seismic waveforms follows the form: ##EQU9## where, M is the total number of traces, S m (w) are the downgoing waves in the earth formation between the receivers and the reflecting interface, and t m is the moveout time".
Claim 9
Independent Claim
219 words
A method for obtaining vertical seismic profiles of an earth formation in which there is located an acoustic wave source having a time-extended, non-impulsive signature, comprising the steps of: (a) providing an array of acoustic wave receivers spaced apart over the earth's surface to produce from said receivers, in response to acoustic waves from said source, a group of seismic waveforms; (b) determining an acoustic velocity of the earth formation between the acoustic wave source and the receivers in the array; (c) applying moveout correction to said group of seismic waveforms to compensate for the differences in the travel time of said seismic waveforms from said source to said receivers; (d) applying to said seismic waveforms a downward continuation filter to focus the array on the location of said source by determining a spatial average of the moveout-corrected seismic waveforms, thereby obtaining an estimate of the acoustic wave source signature; and (e) extracting said acoustic wave source signature from said focused, moveout-corrected seismic data sets to produce seismic profiles of the earth formation "wherein the spatial average of the moveout-corrected seismic waveforms follows the form: ##EQU9## where, M is the total number of traces, S m (w) are the downgoing waves in the earth formation between the receivers and the reflecting interface, and t m is the moveout time".
Claim 10
Dependent Claim
17 words
The method recited in claim 7 wherein the array of receivers is a linear array of receivers.
Claim 11
Dependent Claim
15 words
The method recited in claim 7 wherein the array of receivers is a multi-dimensional array.
Claim 12
Dependent Claim
14 words
The method recited in claim 9 wherein the multi-dimensional array is a two-dimensional array.
Claim 13
Dependent Claim
38 words
The method recited in claim 10 further comprising the step of deconvolving the estimate of the acoustic wave source signature to transform the seismic waveforms to a data set that resembles a walkaway vertical seismic profiling data set.
Claim 14
Dependent Claim
54 words
The method recited in claim 11 wherein the deconvolving step comprises the steps of: constructing a deconvolution filter by taking the inverse amplitude at each frequency of the Fourier transform of the acoustic wave source signature; and multiplying the inverse amplitude at each frequency by an impulsive response for the source drill bit signature.
Claim 15
Dependent Claim
38 words
The method recited in claim 12 wherein the deconvolution filter follows the form: ##EQU10## where f(ω) is the complex conjugate of f(ω), ##EQU11## is the inverse amplitude of f(ω), and D(ω) is a signature of the acoustic source.
Claim 16
Dependent Claim
49 words
The method recited in claim 13 wherein the signature of the acoustic wave source follows the form: D(ω)=e.sup.iωt m, where, t m is the time it takes an acoustic wave to travel from a position of the acoustic wave source in the earth to the receivers in the array.
Claim 17
Dependent Claim
34 words
The method recited in claim 14 wherein the receivers are positioned in the two-dimensional array with a breadth and length substantially the same as the depth of the acoustic wave source in the earth.
Claim 18
Dependent Claim
24 words
The method recited in claim 15 wherein the receivers in the two-dimensional array are arranged in a substantially rectangular pattern of rows and columns.
Claim 19
Independent Claim
217 words
A method for obtaining vertical seismic profiles of an earth formation in which there is located an acoustic wave source having a time-extended, non-impulsive signature, comprising the steps of: (a) providing an array of acoustic wave receivers spaced apart over the earth's surface to produce from said receivers, in response to acoustic waves from said source, a group of seismic waveforms; (b) determining an acoustic velocity of the earth formation between the acoustic wave source and the receivers in the array; (c) applying moveout correction to said group of seismic waveforms to compensate for the differences in the travel time of said seismic waveforms from said source to said receivers; (d) determining a spatial average of the moveout-corrected seismic waveforms, thereby obtaining an estimate of the acoustic wave source signature wherein the spatial average of the moveout-corrected traces follows the form: ##EQU12## where, M is the total number of traces, S m (w) are the downgoing waves in the earth formation between the receivers and the reflecting interface, and t m is the moveout time, (e) extracting said acoustic wave source signature from said moveout-corrected seismic data sets; and (f) deconvolving the estimate of the acoustic wave source signature to transform the seismic waveforms to a data set that resembles a walkaway vertical seismic profiling data set.
Claim 20
Independent Claim
217 words
A method for obtaining vertical seismic profiles of an earth formation in which there is located an acoustic wave source having a time-extended, non-impulsive signature, comprising the steps of: (a) providing an array of acoustic wave receivers spaced apart over the earth's surface to produce from said receivers, in response to acoustic waves from said source, a group of seismic waveforms; (b) determining an acoustic velocity of the earth formation between the acoustic wave source and the receivers in the array; (c) applying moveout correction to said group of seismic waveforms to compensate for the differences in the travel time of said seismic waveforms from said source to said receivers; (d) determining a spatial average of the moveout-corrected seismic waveforms, thereby obtaining an estimate of the acoustic wave source signature wherein the spatial average of the moveout-corrected traces follows the form: ##EQU12## where, M is the total number of traces, S m (w) are the downgoing waves in the earth formation between the receivers and the reflecting interface, and t m is the moveout time, (e) extracting said acoustic wave source signature from said moveout-corrected seismic data sets; and (f) deconvolving the estimate of the acoustic wave source signature to transform the seismic waveforms to a data set that resembles a walkaway vertical seismic profiling data set.
Claim 21
Dependent Claim
54 words
The method recited in claim 17 wherein the deconvolving step comprises the steps of: constructing a deconvolution filter by taking the inverse amplitude at each frequency of the Fourier transform of the acoustic wave source signature; and multiplying the inverse amplitude at each frequency by an impulsive response for the source drill bit signature.
Claim 22
Dependent Claim
39 words
The method recited in claim 18 wherein the deconvolution filter follows the form: ##EQU13## where f(ω) is the complex conjugate of f(ω), ##EQU14## is the inverse amplitude of f(ω), and D(ω) is a signature of the acoustic wave source.
Claim 23
Dependent Claim
49 words
The method recited in claim 19, wherein the signature of the acoustic wave source follows the form: D(ω)=e.sup.iωt m, where, t m is the time it takes an acoustic wave to travel from a position of the acoustic wave source in the earth to the receivers in the array.
Claim 24
Dependent Claim
15 words
The method recited in claim 20 wherein the array of receivers comprises a two-dimensional array.
Claim 25
Dependent Claim
33 words
The method recited in claim 21 wherein the receivers are positioned in the two-dimensional array with a breadth and length substantially the same as the depth of the drill bit in the earth.
Claim 26
Dependent Claim
24 words
The method recited in claim 22 wherein the receivers in the two-dimensional array are arranged in a substantially rectangular pattern of rows and columns.