Time-space varying spectra for seismic processing
First Claim
1. A method for estimating amplitude and phase spectra of data consisting of time-varying sensor signals sampled continuously in time with uniform high frequency-resolution, comprising:
- (a) obtaining a representation of said data sampled at an input (Δ
T) time-rate wherein the data are acquired by deploying a plurality of seismic sensors proximate a surface of the earth or in a body of water, the data representing seismic amplitude detected by the sensors with respect to time in response to actuation of a seismic energy source;
(b) specifying an output sample time-rate (Δ
T′
) that is an integer multiple of Δ
T;
(c) specifying a data analysis window Δ
t that is larger than the output sample time rate (Δ
T′
), wherein the analysis window is an integer multiple of Δ
T;
(d) specifying a frequency sample rate (Δ
f);
(e) computing in a processor a time window (2/Δ
f) that would produce the frequency sample rate and that is an integer multiple of the input time rate (Δ
T);
(f) generating in the processor a model that extrapolates data inside the data analysis window to fill the frequency sample rate (2/Δ
f) window, wherein(g) the model uses a continuity relationship between data within and data outside of the data analysis (Δ
t) window,(h) wherein the model has the property that forward and backward extrapolated values decrease in amplitude with respect to time from edges of the data analysis (Δ
t) window,(i) capturing data in the processor within the data analysis (Δ
t) window at a start of data time;
(j) extrapolating in the processor in forward and backward directions the captured data to fill the (2/Δ
f) time window;
(k) computing fast Fourier transform (FFT) coefficients in the processor for the data in the (2/Δ
f) time window;
(l) incrementing in the processor by the output sample time (Δ
T′
) from the start time of data capture for a next FFT computation;
(m) repeating (i) through (l) until an end of data time is reached; and
at least one of(n) saving in a storage medium the FFT coefficients sampled at (Δ
T′
, Δ
f) intervals, and(o) saving in the storage medium a transformation of the FFT coefficients into amplitude and phase spectra sampled at (Δ
T′
, Δ
f) intervals.
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Abstract
A method and visualization apparatus for spectral analysis of time-and-space varying signals enables high resolution investigation of 3D seismic data for the exploration of oil and gas. The method extrapolates multi-resolution short windows into an average long window then computes its FFT. Extrapolation uses the continuity relationship between data inside and outside of short windows. Applications of the method are illustrated with graphical screen 3D volume displays of amplitude spectra, dip and azimuth, curvature and faults (figure below). Aside from high resolution these displays improve the productivity of a seismic interpreter.
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Citations
6 Claims
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1. A method for estimating amplitude and phase spectra of data consisting of time-varying sensor signals sampled continuously in time with uniform high frequency-resolution, comprising:
-
(a) obtaining a representation of said data sampled at an input (Δ
T) time-rate wherein the data are acquired by deploying a plurality of seismic sensors proximate a surface of the earth or in a body of water, the data representing seismic amplitude detected by the sensors with respect to time in response to actuation of a seismic energy source;(b) specifying an output sample time-rate (Δ
T′
) that is an integer multiple of Δ
T;(c) specifying a data analysis window Δ
t that is larger than the output sample time rate (Δ
T′
), wherein the analysis window is an integer multiple of Δ
T;(d) specifying a frequency sample rate (Δ
f);(e) computing in a processor a time window (2/Δ
f) that would produce the frequency sample rate and that is an integer multiple of the input time rate (Δ
T);(f) generating in the processor a model that extrapolates data inside the data analysis window to fill the frequency sample rate (2/Δ
f) window, wherein(g) the model uses a continuity relationship between data within and data outside of the data analysis (Δ
t) window,(h) wherein the model has the property that forward and backward extrapolated values decrease in amplitude with respect to time from edges of the data analysis (Δ
t) window,(i) capturing data in the processor within the data analysis (Δ
t) window at a start of data time;(j) extrapolating in the processor in forward and backward directions the captured data to fill the (2/Δ
f) time window;(k) computing fast Fourier transform (FFT) coefficients in the processor for the data in the (2/Δ
f) time window;(l) incrementing in the processor by the output sample time (Δ
T′
) from the start time of data capture for a next FFT computation;(m) repeating (i) through (l) until an end of data time is reached; and at least one of (n) saving in a storage medium the FFT coefficients sampled at (Δ
T′
, Δ
f) intervals, and(o) saving in the storage medium a transformation of the FFT coefficients into amplitude and phase spectra sampled at (Δ
T′
, Δ
f) intervals.- View Dependent Claims (2, 3)
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4. A method for estimating amplitude and phase spectra of seismic data sampled continuously in time with uniform high frequency-resolution, comprising:
-
(a) obtaining a representation of the seismic data sampled at an input time rate (Δ
T), wherein the data seismic are acquired by deploying a plurality of seismic sensors proximate a surface of the earth or in a body of water, the data representing seismic amplitude detected by the sensors with respect to time in response to actuation of a seismic energy source;(b) specifying an output time-rate (Δ
T′
) that is an integer multiple of the input time rate Δ
T;(c) specifying a data analysis window (Δ
t) that is larger than the output time rate (Δ
T′
), wherein the analysis window is an integer multiple of said Δ
T;(d) specifying a frequency sample rate (Δ
f);(e) computing in a processor a time window (2/Δ
f) that would produce the frequency said sample and is an integer multiple of the input time rate (Δ
T);(f) generating a model in a processor that extrapolates data inside the data analysis window to fill the (2/Δ
f) time window, wherein(g) the model uses a continuity relationship between data within and outside of the data analysis (Δ
t) window,(h) the model has the property that forward and backward extrapolated values decrease in amplitude with respect to time from edges of the data analysis (Δ
t) window;(i) capturing data within the data analysis (Δ
t) window at a start of data time;(j) extrapolating in forward and backward directions the captured data in the processor to fill the (2/Δ
f) time window;(k) computing fast Fourier transform (FFT) coefficients in the processor of data in the (2/Δ
f) time window;(l) incrementing by the output sample time (Δ
T)′
the start time of data capture for a next FFT computation;(m) repeating (i) through (l) until and end of data time is reached; and at least one of (n) saving in a storage medium the FFT coefficients sampled at (Δ
T′
,Δ
f) intervals, and(o) saving in the storage medium a transformation of the FFT coefficients into amplitude and phase spectra sampled at (Δ
T′
,Δ
f) intervals.- View Dependent Claims (5, 6)
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Specification