Downhole fluid analysis method and apparatus for determining viscosity

Patent metadata

Field	Value
Publication number	US-10228325-B2
Application number	US-201415027227-A
Country	US
Kind code	B2
Filing date	Oct 3, 2014
Priority date	Oct 4, 2013
Publication date	Mar 12, 2019
Grant date	Mar 12, 2019

Abstract

The present disclosure relates to a downhole fluid analysis method that includes withdrawing formation fluid into a downhole tool at a plurality of stations within a wellbore, analyzing the formation fluid within a fluid analyzer of a downhole tool to determine properties of the formation fluid for the plurality of stations, and developing, based on the determined properties of the formation fluid, a relationship for predicting viscosity from a measured optical density.

First claim

What is claimed is:

1. A downhole fluid analysis method comprising:
withdrawing formation fluid into a downhole tool at a plurality of stations within a wellbore;
analyzing the formation fluid within a fluid analyzer of the downhole tool to determine properties of the formation fluid for the plurality of stations, the fluid analyzer comprising at least one of an optical spectrometer and a gas analyzer comprising a light source and a detector; and
measuring, via the at least one of the optical spectrometer and the gas analyzer, an optical density of the formation fluid and a gas oil ratio of the formation fluid;
measuring, via a temperature sensor coupled to the fluid analyzer, a temperature of the formation fluid;
measuring, via a pressure sensor coupled to the fluid analyzer, a pressure of the formation fluid;
developing, via a controller coupled to the fluid analyzer, and based on the determined properties of the formation fluid, a relationship for predicting viscosity from the measured optical density; and
calculating, via the controller, a viscosity using said relationship;
wherein developing comprises selecting, based on whether asphaltene clusters exist within the formation fluid, an equation for predicting viscosity, and wherein said equation is one of a heavy oil equation or a black oil equation;
wherein the heavy oil equation is

ln
⁡

(

η

η
0

)

=

c
⁡

(

a
1

+

b
1

⁢
OD

T

)

3.3018

+

1
3

⁢

ln
⁡

(

GOR
ref

GOR

)

+

1.392
×

10

-
2

⁢

(

P
-

P
ref

)

wherein the black oil equation is

ln
⁡

(

η

η
0

)

=

(

c
1

+

c
2

⁢
OD

)

⁢

(

T
g

T

)

3.3018

+

1
3

⁢

ln
⁡

(

GOR
ref

GOR

)

+

1.392
×

10

-
2

⁢

(

P
-

P
ref

)

wherein η is the viscosity of the formation fluid, η 0 is the viscosity at a reference state, c is a coefficient, OD is the optical density of the formation fluid, GOR is the gas oil ratio of the formation fluid at temperature T and pressure P, T ref and P ref are respectively the temperature and pressure of the formation fluid at the reference state, and a 1 , b 1 , c 1 , and c 2 are adjustable parameters determined during the developing.

2. The downhole fluid analysis method of claim 1 , wherein analyzing comprises measuring an absorption spectra of the formation fluid.

3. The downhole fluid analysis method of claim 1 , wherein analyzing comprises measuring a viscosity of the formation fluid.

4. The downhole fluid analysis method of claim 1 , wherein analyzing comprises determining concentrations of components within the formation fluid.

5. The downhole fluid analysis method of claim 1 , wherein developing comprises designating one of the plurality of stations as a reference station and employing the determined properties for the designated station as reference values within the relationship.

6. The downhole fluid analysis method of claim 1 , comprising:
withdrawing additional formation fluid into the downhole tool at an additional station within a wellbore;
comparing a measured viscosity at the additional station to the predicted viscosity calculated using the relationship; and
determining whether the measured viscosity and the predicted viscosity are within a tolerance of one another.

7. The downhole fluid analysis method of claim 6 , comprising initiating withdrawal of furth

Assignees

• Schlumberger Technology Corp

Inventors

• Zuo Youxiang
• Dumont Hadrien
• Jackson Richard
• De Santo Ilaria
• Mullins Oliver C
• Ayan Cosan

Classifications

• G01N2011/008

  optical properties · CPC title

• E21B49/10

  using side-wall fluid samplers or testers · CPC title

• E21B49/0875

  determining specific fluid parameters · CPC title

• G01N30/88

  Integrated analysis systems specially adapted therefor, not covered by a single one of the groups G01N30/04 - G01N30/86 · CPC title

• G01N21/5907 Primary

  Densitometers · CPC title