Applying shrinkage factor to real-time OBM filtrate contamination monitoring

Patent metadata

Field	Value
Publication number	US-10352161-B2
Application number	US-201514975704-A
Country	US
Kind code	B2
Filing date	Dec 18, 2015
Priority date	Dec 30, 2014
Publication date	Jul 16, 2019
Grant date	Jul 16, 2019

Abstract

A downhole tool operable to pump a volume of contaminated fluid from a subterranean formation during an elapsed pumping time while obtaining in-situ, real-time data associated with the contaminated fluid. The contaminated fluid includes native formation fluid and oil-based mud (OBM) filtrate. A shrinkage factor of the contaminated fluid is determined based on the in-situ, real-time data. The contaminated fluid shrinkage factor is fit relative to pumped volume or pumping time to obtain a function relating the shrinkage factor with pumped volume or elapsed pumping time. A shrinkage factor of the native formation fluid is determined based on the function. A shrinkage factor of the OBM filtrate is also determined. OBM filtrate volume percentage is determined based on the shrinkage factor of the native formation fluid and the shrinkage factor of the OBM filtrate.

First claim

What is claimed is:

1. A method, comprising:
disposing a downhole tool in a wellbore that extends into a subterranean formation, wherein the downhole tool is in communication with surface equipment disposed at a wellsite surface from which the wellbore extends; and
operating at least one of the downhole tool and the surface equipment to:
pump a volume V of contaminated fluid from the subterranean formation during an elapsed pumping time t while obtaining in-situ, real-time data associated with the contaminated fluid flowing through the downhole tool, wherein the contaminated fluid comprises native formation fluid and oil-based mud (OBM) filtrate;
determine a shrinkage factor b of the contaminated fluid based on the in-situ, real-time data;
fit the contaminated fluid shrinkage factor b relative to either the pumped volume V or the elapsed pumping time t to obtain a function relating the shrinkage factor b with either the pumped volume V or the elapsed pumping time t;
determine a shrinkage factor b 0 of the native formation fluid based on the obtained function;
determine a shrinkage factor b OBM of the OBM filtrate; and
determine a volume percentage ν OBM of the OBM filtrate within the contaminated fluid based on the determined shrinkage factor b 0 of the native formation fluid and the determined shrinkage factor b OBM of the OBM filtrate; and

further operating the downhole tool based at least in part on the determined volume percentage ν OBM of the OBM filtrate.

2. The method of claim 1 further comprising operating at least one of the downhole tool and the surface equipment to determine a formation volume factor B o based on the in-situ, real-time data, wherein the shrinkage factor b of the contaminated fluid is determined based on the determined formation volume factor B o , and wherein the formation volume factor B o is determined based on:
a gas-oil-ratio (GOR) of the contaminated fluid determined based on the in-situ, real-time data;
a molecular weight of gas in the contaminated fluid determined based on the in-situ, real-time data;
a density of the contaminated fluid determined based on the in-situ, real-time data; and
a density of the contaminated fluid at stock tank conditions determined based on the in-situ, real-time data.

3. The method of claim 1 wherein the function is a power function.

4. The method of claim 1 wherein the function is b=b 0 /βV −γ , where, for fitting purposes, b 0 , β, and γ are adjustable parameters determined via fitting the obtained in-situ, real-time data.

5. The method of claim 4 wherein, for fitting purposes, b 0 , β, and γ are determined via utilization of at least a portion of:

v
OBM

=

OD
0

-
OD

OD
0

-

OD
OBM

=

ρ
0

-
ρ

ρ
0

-

ρ
OBM

=

b
⁢

GOR
0

-
GOR

GOR
0

=

GOR
0

-
GOR

GOR
0

+

(

B

o
⁢

⁢
0

-
1

)

⁢
GOR

=

b
-

b
0

b
OBM

-

b
0

=

β
⁢

⁢

V

-
γ

where:
B o0 is formation volume factor of the native formation fluid;
b OBM is shrinkage factor of the OBM filtrate;
OD is optical density of the contaminated fluid, which is included in the obtained in-situ, real-time data;
OD 0 is optical density of the native formation fluid;
OD OBM is optical density of the OBM filtrate;
GOR is gas-oil-ratio (GOR) of the contaminated fluid;
GOR 0 is GOR of the native formation fluid;
ρ is density of the contaminated fluid;
ρ 0 is density of the native formation fluid; and
ρ OBM is density of the OBM filtrate.

6. The method of claim 1 wherein the function is b=b 0 −βt −γ , where, for fitting purposes, b 0 , β, and γ are adjustable parameters determined via fitting the obtained i

Assignees

• Schlumberger Technology Corp

Inventors

• Zuo Youxiang
• Gisolf Adriaan
• Wang Kang
• Lee Ryan Sangjun

Classifications

• E21B49/10 Primary

  using side-wall fluid samplers or testers · CPC title

• E21B49/0875

  determining specific fluid parameters · CPC title

• E21B2049/085

  Fixed Constructions · mapped topic