Methods and systems for correction of oil-based mud filtrate contamination on saturation pressure

Patent metadata

Field	Value
Publication number	US-11187693-B2
Application number	US-201916531640-A
Country	US
Kind code	B2
Filing date	Aug 5, 2019
Priority date	Nov 6, 2014
Publication date	Nov 30, 2021
Grant date	Nov 30, 2021

Abstract

Embodiments of the disclosure can include systems, methods, and devices for determining saturation pressure of an uncontaminated fluid. Downhole saturation pressure measurements and downhole OBM filtrate contamination of a contaminated fluid may be obtained and a relationship may be determined between the saturation pressure measurements and OBM filtrate contamination. The relationship may be extrapolated to zero OBM filtrate contamination to determine the saturation pressure of the uncontaminated fluid. In some embodiments, OBM filtrate contamination may be determined from downhole saturation pressure measurements during pumpout of a fluid.

First claim

What is claimed is:

1. A system comprising,
a downhole tool operable within a wellbore extending into a subterranean formation:
a controller coupled to the downhole tool; and
a non-transitory tangible machine-readable memory coupled to a processor of the controller, the non-transitory tangible machine-readable memory storing machine-readable instructions that when executed by the processor cause the processor to perform operations comprising:
obtaining, by using at least one property of a contaminated fluid measured downhole by a downhole tool, oil-based mud (OBM) filtrate contamination of the contaminated fluid, wherein the contaminated fluid comprises uncontaminated fluid and OBM filtrate;
obtaining downhole saturation pressure measurements of the contaminated fluid;

determining a relationship between the downhole saturation pressure measurements and the OBM filtrate contamination, wherein the operation of determining a relationship between the downhole saturation pressure measurements and the downhole OBM filtrate contamination comprises:
generating a plot of the downhole saturation pressure measurements versus the downhole OBM filtrate contamination; and
performing a non-linear regression to determine a non-linear function between the downhole saturation pressure measurements and the downhole OBM filtrate contamination;
extrapolating the determined relationship between the downhole saturation pressure measurements and the OBM filtrate contamination to a zero OBM filtrate contamination; and
determining a saturation pressure of the uncontaminated fluid at the zero OBM filtrate contamination.

2. The system of claim 1 , wherein the downhole saturation pressure measurements comprise bubble point measurements and the saturation pressure of the uncontaminated fluid is a bubble point pressure of the uncontaminated fluid.

3. The system of claim 1 , wherein the operation of determining a relationship between the downhole saturation pressure measurements and the downhole OBM filtrate contamination comprises:
generating a plot of the downhole saturation pressure measurements versus the downhole OBM filtrate contamination; and
performing a linear regression to determine a linear function between the downhole saturation pressure measurements and the downhole OBM filtrate contamination.

4. The system of claim 1 , wherein the at least one property comprises an optical density, a gas/oil ratio, a mass density, a pressure gradient, a pumpout volume, or a pumpout time.

5. The system of claim 1 , wherein the operation of determining a relationship between the downhole saturation pressure measurements and the OBM filtrate contamination comprises determining a threshold level of OBM filtrate contamination.

6. The system of claim 1 , comprising surface equipment located at a wellsite surface associated with a wellbore, wherein the surface equipment comprises the controller.

7. The system of claim 1 , wherein the operation of extrapolating the determined relationship between the downhole saturation pressure measurements and the OBM filtrate contamination to a zero OBM filtrate contamination comprises extrapolating the non-linear function to a zero OBM filtrate contamination.

8. The system of claim 1 , wherein the at least one property comprises a gas/oil ratio.

9. The system of claim 1 , wherein the at least one property comprises a gas/oil ratio and an optical density.

10. The system of claim 1 , wherein the at least one property comprises a gas/oil ratio and a pumpout volume or a pumpout time.

11. The system of claim 3 , wherein the operation of extrapolating the determined relationship between the downhole saturation pressure measurements and the OBM filtrate contamination to a zero OBM filtrate contamination comprises extrapolating the linear function to a zero OBM filtrate contamination.

12. The system of claim 5 , wherein the threshold level of OBM filtrate contamination is 40% by volume or less.

Assignees

• Schlumberger Technology Corp

Inventors

• Zuo Youxiang
• Harrison Christopher
• Gisolf Adriaan
• Ayan Cosan
• Toribio Michael Mallari
• Desai Chetankumar Natwarlal
• Mullins Oliver Clinton
• Sullivan Matthew T
• Smythe Elizabeth

Classifications

• E21B47/00

  Survey of boreholes or wells (monitoring pressure or flow of drilling fluid E21B21/08) · CPC title

• E21B49/005 Primary

  Testing the nature of borehole walls or the formation by using drilling mud or cutting data · CPC title

• E21B49/08

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

• G01N7/00

  Analysing materials by measuring the pressure or volume of a gas or vapour · CPC title

• G01N33/2823 Primary

  Raw oil, drilling fluid or polyphasic mixtures · CPC title