Method and device for the concurrent determination of fluid density and viscosity in-situ

Patent metadata

Field	Value
Publication number	US-2016108729-A1
Application number	US-201314889955-A
Country	US
Kind code	A1
Filing date	Jul 24, 2013
Priority date	Jul 24, 2013
Publication date	Apr 21, 2016
Grant date	—

Abstract

A measurement device and method for determining the density and viscosity of a fluid in a downhole environment from vibration frequencies of a sample cavity.

First claim

What is claimed is:

1 . A method for determining the density and viscosity of a fluid, comprising:
receiving a fluid sample into a sample tube of a measurement device; determining a resonant frequency and Q value of the tube containing fluid; calculating a density of the fluid using the resonant frequency; calculating a viscosity of the fluid based on the density and Q value.

2 . The method of claim 1 , wherein the measurement device is a vibrating tube densitometer.

3 . The method of claim 2 , wherein the vibrating tube densitometer contains vibration source circuits that induce oscillation within a vibrating tube.

4 . The method of claim 3 , wherein the density and the viscosity of the fluid are calculated utilizing vibration detector circuits that measure oscillation in the vibrating tube densitometer.

5 . The method of claim 4 , wherein the vibration source circuits comprise electromechanical circuits.

6 . The method of claim 4 , wherein the vibration source circuits comprise electrical circuits.

7 . The method of claim 4 , wherein the vibration source circuits induce a time decaying oscillation that the vibration detector circuits record as a function of time and transform into frequency domain to yield a power spectral density from which resonance frequency and the Q value are determined.

8 . The method of claim 4 , wherein the vibration source circuits induce a variable frequency signal to excite the tube containing fluid into oscillation that the vibration detector circuits record as a function of the induced frequency signal, yielding a power spectral density as a function of the induced frequency signal, from which the resonance frequency and the Q value can be determined.

9 . The method of claim 3 , wherein a varying frequency drive signal from the vibration source circuits is used to drive the vibrating tube densitometer and a measured response allows a frequency and bandwidth of a resonant peak to be measured.

10 . The method of claim 2 , wherein a time varying frequency signal from the vibrating tube densitometer allows the resonant frequency to be measured and the Q value to be determined.

11 . The method of claim 1 , further comprising measuring Q of the fluid and calculating the viscosity of the fluid based on the relationship between Q of the fluid and density of the fluid.

12 . The method of claim 1 , wherein viscosity (η) of the fluid is determined by using the equation

Q
ρ

∝

1

ρη

such that

η
=

B
2

(

Q
-

A



ρ

)

2

,

where ρ is density of the fluid and A and B are the intercept and slope of the linear fit of Q/ρ plotted against 1/√{square root over (ρη)}.

13 . A downhole tool comprising:
a tube that receives a sample fluid having a density; a rigid pressure housing enclosing said tube and forming an annular area between said tube and said pressure housing; a vibration source attached to said tube; at least one vibration detector; and a measurement module electrically coupled to said vibration source and said vibration detector, wherein the measurement module is configured to measure resonance frequency and Q to determine a density and a viscosity of the sample fluid using frequency and amplitude measurements of the tube; wherein said vibration source excites the tube containing fluid into oscillation; and wherein said vibration detector measures such oscillation.

14 . The downhole tool of claim 13 , wherein the downhole tool is a vibrating tube densitometer.

15 . The downhole tool of claim 13 , wherein the vibration source comprises circuits that induce oscillation within a vibrating tube.

16 . The downhole tool of claim 15 , wherein the circuits induce a time decaying oscillation that is recorded as a function of time and transformed into frequency domain to yield a power spectral density from which the Q value can be determined.

17 . The downhole tool of claim 15 , wherein the circuits induce a variable frequency signal to excite the tube containing fluid into oscillation and the response of the tube is recorded as a function of the induced frequency signal, yielding a power spectral density as a function of the induced frequency signal, from which the Q value is determined.

18 . The downhole tool of claim 14 , wherein a varying frequency drive signal from the vibrating tube densitometer allows the bandwidth of the resonant peak to be measured.

19 . The downhole tool of claim 14 , wherein a time decaying amplitude signal allows viscosity to be determined from the measured resonant frequency and Q value of a vibrating tube.

20 . The downhole tool of claim 19 , wherein viscosity (η) of the fluid is determined by using the equation

Q
ρ

∝

1

ρη

such that

η
=

B
2

(

Q
-

A



ρ

)

2

,

where ρ is density of the fluid and A and B are the intercept and slope of the linear fit of Q/ρ plotted against 1/√{square root over (ρη)}.

Assignees

• Gao Li
• Pelletier Michael T
• Masino James
• Proett Mark Anton
• Halliburton Energy Services Inc

Inventors

• Li Gao
• Pelletier Michael T
• Proett Mark Anton
• Masino James

Classifications

• G01N11/16

  by measuring damping effect upon oscillatory body · CPC title

• G01N9/002

  using variation of the resonant frequency of an element vibrating in contact with the material submitted to analysis (G01N9/34 takes precedence) · CPC title

• E21B49/081 Primary

  with down-hole means for trapping a fluid sample (E21B49/10 takes precedence) · CPC title

• E21B2049/085

  Fixed Constructions · mapped topic

• E21B49/08

  Obtaining fluid samples or testing fluids, in boreholes or wells · CPC title