# US 2017/0254197 A1 · Fluid viscometer suitable for downhole use

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- Number: US 2017/0254197 A1
- Document ID: US20170254197A1
- Status: Published application
- Kind: A1
- Application number: 15/512,754
- Filed: 2014-10-24
- Published: 2017-09-07
- Earliest claimed: 2014-10-24
- Assignees: Halliburton Energy Services, Inc.
- Applicants: Halliburton Energy Services, Inc.
- Inventors: Li Gao; Michael T. Pelletier; James E. Masino
- Web page: https://patentgrep.com/patent/US20170254197A1

## CPC

- E21B 49/08: Obtaining fluid samples or testing fluids, in boreholes or wells
- E21B 28/00: Vibration generating arrangements for boreholes or wells, e.g. for stimulating production ({for fishing for or freeing objects E21B31/005;} for transmitting measuring-signals E21B47/14; for geophysical measurements G01V1/02)
- E21B 31/005: {using vibrating or oscillating means}
- E21B 47/005: Monitoring or checking of cementation quality or level
- G01N 11/167: {Sample holder oscillates, e.g. rotating crucible}
- E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)

## Abstract

An illustrative method for measuring a fluid viscosity that includes vibrating a tube containing a fluid of interest, obtaining a vibration signal from the vibrating tube, deriving a system energy loss rate measurement from the vibration signal, calculating an energy loss rate for the fluid of interest from the system energy loss rate measurement and a reference energy loss rate measurement, and generating a viscosity measurement of the fluid of interest based on the energy loss rate for the fluid of interest and a density of the fluid of interest.

## Claims

### Claim 1

A method for measuring a fluid viscosity, comprising:
vibrating a tube, the vibrating tube containing a fluid of interest;
obtaining a vibration signal from the vibrating tube ;
deriving a system energy loss rate measurement from the vibration signal;
calculating an energy loss rate for the fluid of interest from the system energy loss rate measurement and a reference energy loss rate measurement; and
generating a viscosity measurement of the fluid of interest based on the energy loss rate for the fluid of interest and a density of the fluid of interest.

### Claim 2 (depends on 1)

The method of claim 1, further comprising:
displaying the viscosity measurement; and
storing the viscosity measurement in a non-transient information storage medium.

### Claim 3 (depends on 1)

The method of claim 1, further comprising:
obtaining a reference signal from the vibrating tube while the vibrating tube contains a reference fluid; and
deriving the reference energy loss rate measurement from the reference signal.

### Claim 4 (depends on 1)

The method of claim 1, further comprising:
deriving a frequency response by performing a frequency sweep while vibrating the tube and obtaining the vibration signal; and
identifying a resonant frequency associated with a peak in the frequency response.

### Claim 5 (depends on 1)

The method of claim 1, wherein the system energy loss rate measurement is a quality factor Qm, the reference energy loss rate measurement is a quality factor Qref, and the energy loss rate for the fluid of interest is a quality factor Qfi.

### Claim 6 (depends on 5)

The method of claim 5, wherein said determining an energy loss rate measurement includes:
transforming the vibration signal to obtain a signal spectrum; and
deriving the quality factor Qm from a resonance peak in the signal spectrum.

### Claim 7 (depends on 5)

The method of claim 5, wherein the fluid of interest quality factor Qfi is representable as
Q
fi

(
T
)
=
Q
ref

(
T
)
×
Q
m

(
T
)
Q
ref

(
T
)
-
Q
m

(
T
)
.

### Claim 8 (depends on 5)

The method of claim 5, wherein determining the quality factors Qm and Qref may further include:
determining a resonance frequency f0; and
measuring a full-width half-maximum (FWHM) of a peak at the resonance frequency f0,
wherein the quality factor may be determined by the formula f0/FWHM.

### Claim 9 (depends on 1)

The method of claim 1, wherein the system energy loss rate measurement is a time decay constant τm, the reference energy loss rate measurement is a time decay constant τref, and the energy loss rate for the fluid of interest is a time decay constant τfi.

### Claim 10 (depends on 9)

The method of claim 9, wherein said deriving the system energy loss rate measurement includes:
applying a Hilbert transform to the vibration signal to determine a vibration signal envelope; and
deriving the time decay constant τm from the envelope.

### Claim 11 (depends on 9)

The method of claim 9, wherein the fluid of interest time decay constant τfi is representable as
τ
fi

(
T
)
=
τ
ref

(
T
)
×
τ
m

(
T
)
τ
ref

(
T
)
-
τ
m

(
T
)
.

### Claim 12

A fluid viscosity measurement system that comprises:
a tube that receives a fluid of interest;
a vibration source that drives the tube to vibrate;
a sensor coupled to the tube to receive a vibration signal from the tube;
a processor coupled to the sensor to implement a viscosity measurement method comprising:
deriving a system energy loss rate measurement from the vibration signal;
calculating an energy loss rate for the fluid of interest from the system energy loss rate measurement and a reference energy loss rate measurement; and
generating a viscosity measurement for the fluid of interest based on the energy loss rate for the fluid of interest and a density of the fluid of interest.

### Claim 13 (depends on 12)

The system of claim 12, wherein the viscosity measurement method further comprises:
displaying the viscosity measurement; and
storing the viscosity measurement in a non-transient information storage medium.

### Claim 14 (depends on 12)

The system of claim 12, wherein the viscosity measurement method further comprises:
obtaining a reference signal from the vibrating tube while the vibrating tube contains a reference fluid; and
deriving the reference energy loss rate measurement from the reference signal.

### Claim 15 (depends on 12)

The system of claim 12, wherein the viscosity measurement method further comprises:
deriving a frequency response by performing a frequency sweep while vibrating the tube and obtaining the vibration signal; and
identifying a resonant frequency associated with a peak in the frequency response.

### Claim 16 (depends on 12)

The system of claim 12, wherein the system energy loss rate measurement is a quality factor Qm, the reference energy loss rate measurement is a quality factor Qref, and the energy loss rate for the fluid of interest is a quality factor Qfi.

### Claim 17 (depends on 16)

The system of claim 16, wherein said determining the system energy loss rate measurement includes:
transforming the vibration signal to obtain a signal spectrum; and
deriving the quality factor Qm from a resonance peak in the signal spectrum.

### Claim 18 (depends on 16)

The system of claim 16, wherein the fluid of interest quality factor Qfi is representable as
Q
fi

(
T
)
=
Q
ref

(
T
)
×
Q
m

(
T
)
Q
ref

(
T
)
-
Q
m

(
T
)
.

### Claim 19 (depends on 16)

The system of claim 16, wherein determining the quality factors Qm and Qref may further include:
determining a resonance frequency f0;
measuring a full-width half-maximum (FWHM) of a peak at the resonance frequency f0; and
wherein the quality factor may be determined by the formula f0/FWHM.

### Claim 20 (depends on 12)

The system of claim 12, wherein the system energy loss rate measurement is a time decay constant τm, the reference energy loss rate is a time decay constant τref , and the energy loss rate for the fluid of interest is a time decay constant τfi.

### Claim 21 (depends on 20)

The system of claim 20, wherein said deriving the system energy loss rate measurement includes:
applying a Hilbert transform to the vibration signal to determine a vibration signal envelope; and
deriving the time decay constant τm from the envelope.

### Claim 22 (depends on 20)

The system of claim 20, wherein the fluid of interest time decay constant τfi is representable as
τ
fi

(
T
)
=
τ
ref

(
T
)
×
τ
m

(
T
)
τ
ref

(
T
)
-
τ
m

(
T
)
.