Joint time-frequency processing for borehole acoustic arrays

Patent metadata

Field	Value
Publication number	US-9631483-B2
Application number	US-201214413901-A
Country	US
Kind code	B2
Filing date	Jul 12, 2012
Priority date	Jul 12, 2012
Publication date	Apr 25, 2017
Grant date	Apr 25, 2017

Abstract

Various embodiments include apparatus and methods to process acoustic signals according to joint time-frequency processing. The joint time-frequency processing can combine features of both time-based processing and frequency-based processing. This processing may be based on delay calculation from amplitude phases generated from the acoustic signals. The joint time-frequency processing may be applied to a variety of applications to evaluate properties associated with a borehole or surrounding formations. Additional apparatus, systems, and methods are disclosed.

First claim

What is claimed is:

1. A method comprising:
using a processor and data storage device coupled to an acoustic tool to process signals generated from operating the acoustic tool in a borehole such that the using includes
collecting signals from generation of acoustic waves using the acoustic tool;
generating delay values using frequency-based signals, the frequency-based signals correlated to the collected signals, wherein generating the delay values includes
processing the frequency-based signals into a representation that is a series sum of modes, each mode having an amplitude and a pole, and processing the amplitude of a mode such that a delay value is generated; or
processing the frequency-based signals into an amplitude proportional to a sum of products of the frequency-based signals and a corresponding phase factor, the phase factor based on a slowness from a phase coherence of the frequency-based signals, and processing the amplitude such that a delay value is generated; and

evaluating properties associated with the borehole, surrounding formations, or quality of a measurement using the delay values.

2. The method of claim 1 , wherein generating delay values includes
processing the frequency-based signals into a representation that is a series sum of modes, each mode having an amplitude and a pole; and
processing the amplitude of a mode such that a delay value is generated.

3. The method of claim 1 , wherein the method includes converting pressure at receivers of the acoustic tool to voltages expanded into a series sum of modes given by

V
i

⁡

(
f
)

=

∑

n
=
1

N
m

⁢

⁢

A
n

⁡

(

Z
n

)

i
-

i
ref

where f is frequency, N m is a total number of modes in the expansion, A n is a complex valued amplitude of mode n, Z n is a complex valued pole of mode n, and i ref is a reference index, and delay for mode n generated according to

d
n

=

-

ⅆ

ⅆ
f

⁢

(

angle
⁡

(

A
n

)

2
⁢
π

)

.

4. The method of claim 1 , wherein generating delay values includes
processing the frequency-based signals into an amplitude proportional to a sum of products of the frequency-based signals and a corresponding phase factor, the phase factor based on a slowness from a phase coherence of the frequency-based signals; and
processing the amplitude such that a delay value is generated.

5. The method of claim 1 , wherein the method includes collecting voltages from receivers of the acoustic tool and generating delay according to

delay
=

-

ⅆ

ⅆ
f

⁢

(

angle
⁡

(
A
)

2
⁢
π

)

from

A
=

1

N
r

⁢

∑

i
=
1

N
r

⁢

⁢

V
i

⁡

(
f
)

⁢

ⅇ

j2π
⁢

⁢

fs
PC

⁡

(
f
)

⁢

(

z
i

-

z
ref

)

Assignees

• Donderici Burkay
• Cheng Arthur
• Halliburton Energy Services Inc

Inventors

• Donderici Burkay
• Cheng Arthur

Classifications

• E21B49/00 Primary

  Testing the nature of borehole walls; Formation testing; Methods or apparatus for obtaining samples of soil or well fluids, specially adapted to earth drilling or wells · CPC title

• G01V1/48 Primary

  Processing data · CPC title

• E21B47/12 Primary

  Means for transmitting measuring-signals or control signals from the well to the surface, or from the surface to the well, e.g. for logging while drilling · CPC title