# US 10,371,690 B2 · Methods and systems for correction of oil-based mud filtrate contamination on saturation pressure

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- Number: US 10,371,690 B2
- Document ID: US10371690B2
- Status: Granted
- Kind: B2
- Application number: 14/535,199
- Filed: 2014-11-06
- Published: 2016-05-12
- Granted: 2019-08-06
- Earliest claimed: 2014-11-06
- Assignees: Schlumberger Technology Corporation
- Applicants: Schlumberger Technology Corporation
- Inventors: Youxiang Zuo; Christopher Harrison; Adriaan Gisolf; Cosan Ayan; Michael Mallari Toribio; Chetankumar Natwarlal Desai; Oliver Clinton Mullins; Matthew T. Sullivan; Elizabeth Smythe
- Web page: https://patentgrep.com/patent/US10371690B2

## CPC

- G01N 33/2823: {Raw oil, drilling fluid or polyphasic mixtures}
- E21B 47/00: Survey of boreholes or wells (monitoring pressure or flow of drilling fluid E21B21/08)
- E21B 47/06: Measuring temperature or pressure
- E21B 49/005: {Testing the nature of borehole walls or the formation by using drilling mud or cutting data}
- E21B 49/08: Obtaining fluid samples or testing fluids, in boreholes or wells
- G01N 7/00: Analysing materials by measuring the pressure or volume of a gas or vapour
- G01N 21/31: Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry {(G01N21/72 takes precedence)}
- 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)
- E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS

## 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.

## Claims

### Claim 1

A method, comprising:
initiating a pumpout process of downhole tool positioned in a wellbore;
providing a controller with at least one property of a first fluid measured downhole by the downhole tool, oil-based mud (OBM) filtrate contamination of the first fluid, wherein the first fluid comprises a formation fluid and OBM filtrate;
providing with the controller with downhole saturation pressure measurements of the first fluid measured downhole by the downhole tool;
in the controller, continuously determining a relationship between the downhole saturation pressure measurements and the OBM filtrate contamination;
when the relationship is determined, extrapolating, in the controller, the determined relationship between the downhole saturation pressure measurements and the OBM filtrate contamination to a zero OBM filtrate contamination to obtain a saturation pressure of the formation fluid at the zero OBM filtrate contamination.

### Claim 2 (depends on 1)

The method of claim 1, wherein the downhole saturation pressure measurements comprise bubble point measurements and the saturation pressure of the formation fluid is a bubble point pressure of the formation fluid.

### Claim 3 (depends on 1)

The method of claim 1, wherein 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.

### Claim 4 (depends on 3)

The method of claim 3, wherein 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.

### Claim 5 (depends on 1)

The method 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.

### Claim 6 (depends on 1)

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