Automatic processing of ultrasonic data

Patent metadata

Field	Value
Publication number	US-9513372-B2
Application number	US-201313943791-A
Country	US
Kind code	B2
Filing date	Jul 17, 2013
Priority date	Jan 22, 2013
Publication date	Dec 6, 2016
Grant date	Dec 6, 2016

Abstract

An example method for automatically characterizing an echo contained in an ultrasonic signal generated with an ultrasonic transducer can include receiving data corresponding to the ultrasonic signal, calculating an energy ratio of the ultrasonic signal and localizing the echo using the energy ratio. The method can include windowing a portion of the ultrasonic signal around the localized echo and calculating a Fast Fourier Transform (FFT) and a Hilbert envelop of the windowed portion. The method can include estimating M echo parameters from the FFT and the Hilbert envelope of the windowed portion, where each of the M parameter vectors includes a plurality of echo parameters, calculating M parametric echo models based on each of the M echo parameter vectors and iteratively minimizing a difference between the windowed portion of the ultrasonic signal and a sum of the M parametric echo models.

First claim

What is claimed:

1. A method to image a formation by automatically characterizing an echo contained in an ultrasonic signal, the ultrasonic signal being generated with an ultrasonic transducer, the method comprising:
a. receiving data corresponding to the ultrasonic signal with the ultrasonic transducer of a downhole acoustic tool;
b. calculating an energy ratio of the ultrasonic signal and localizing the echo contained in the ultrasonic signal using the energy ratio; comprising;
b1. calculating an energy ratio function of the ultrasonic signal, wherein the energy ratio function is

E
x

=

a
1

(

∑

i
=

x
+
1

x
+
L

⁢

⁢

E
i

∑

i
=

x
-
L

x
-
1

⁢

⁢

E
i

)

/

(

1
+

a
2

⁢

E
total

)

,

 where Ex is energy at a given data point, a 1 and a 2 are energy adjustment factors, L is a window length,

∑

i
=

x
+
1

x
+
L

⁢

⁢

E
i

 is signal energy,

∑

i
=

x
-
L

x
-
1

⁢

⁢

E
i

 is noise energy and E total is total energy; and
b2. identifying a maximum value of the energy ratio function of the ultrasonic signal, wherein the maximum value corresponds to an approximate location of the echo contained in the ultrasonic signal;

c. windowing a portion of the ultrasonic signal around the localized echo;
d. calculating a Fast Fourier Transform (FFT) and a Hilbert envelop of the windowed portion of the ultrasonic signal;
e. estimating M echo parameter vectors from the FFT and the Hilbert envelope of the windowed portion of the ultrasonic signal, wherein each of the M echo parameter vectors comprises a plurality of echo parameters;
f. calculating M parametric echo models based on each of the M echo parameter vectors; and
g. iteratively minimizing a difference between the windowed portion of the ultrasonic signal and a sum of the M parametric echo models;
transmitting parameters from the M parametric echo models for use in characterizing the formation.

2. The method of claim 1 , wherein calculating an energy ratio function of the ultrasonic signal comprises:
b3. reversing the data corresponding to the ultrasonic signal from a forward order to a reversed order;
b4. calculating the energy ratio function of the reversed ultrasonic signal; and
b5. identifying a maximum value of the energy ratio function of the reversed ultrasonic signal, wherein the maximum value of the energy ratio function of the ultrasonic signal corresponds to a left break of a first echo contained in the ultrasonic signal and the maximum value of the energy ratio function of the reversed ultrasonic signal corresponds to a right break of the first echo contained in the ultrasonic signal.

3. The method of claim 1 , wherein calculating an energy ratio function of the ultrasonic signal comprises:
b3. cropping the data corresponding to the ultrasonic signal;
b4. calculating the energy ratio function of the cropped ultrasonic signal; and
b5. identifying a maximum value of the energy ratio function of the cropped ultrasonic signal, wherein the maximum value of the energy ratio function of the ultrasonic signal corresponds to a left break of a first echo contained in the ultrasonic signal and the maximum value of the energy ratio function of the cropped ultrasonic signal corresponds to a left break of a second echo contained in the ultrasonic signal.

4. The method of claim 1 , wherein the window length (L) is approximately equal to

s
⁢

f
s

f
c

,

where s is a tuning coefficient, f c is a center frequency of the echo of the ultrasonic signal, and f s is a sampling frequency.

5. The method of claim 1 , wherein windowing a portion of the ultrasonic signal around the localized echo comprises applying a half-Hanning taper to data corresponding to one or more sides of the ultrasonic signal outside of the windowed portion of the ultras

Assignees

• Schlumberger Technology Corp

Inventors

• Valero Henri-Pierre
• Pedrycz Adam
• Fujihara Takeo

Classifications

• G01S15/006 Primary

  Theoretical aspects · CPC title

• G01V1/48 Primary

  Processing data · CPC title

• G06F5/00 Primary

  Methods or arrangements for data conversion without changing the order or content of the data handled · CPC title

• G06F17/14

  Fourier, Walsh or analogous domain transformations {, e.g. Laplace, Hilbert, Karhunen-Loeve, transforms (for correlation function computation G06F17/156; spectrum analysers G01R23/16)} · CPC title

• G01N29/46

  by spectral analysis, e.g. Fourier analysis {or wavelet analysis (spectral signal processing per se G06F17/14)} · CPC title