Phase change analysis in logging method

a phase change and logging technology, applied in the field of down hole fluid sampling tools and methods, can solve the problems of delay between phase change and detection, inability to create bubbles down holes, and generally considered impossible, and achieve the effect of measuring accurately

USRE38129E1Inactive Publication Date: 2003-06-03SCHLUMBERGER TECH CORP
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Patent Information

Authority / Receiving Office
US · United States
Current Assignee / Owner
Publication Date
2003-06-03
Estimated Expiration
Not applicable · inactive patent

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Abstract

An improved method of fluid analysis in the borehole of a well. A fluid sampling tool is fitted with a pumpout module that can be used to draw fluids from the formation, circulate them through the instrument, and then expel this fluid to the borehole. It has been determined that certain measurements would be most valuable to implement down hole, such as the formation fluid bubble point and dew point. Accurate bubble point and dew point measurements are made by forming bubbles or a liquid drop in a measured sample, and detecting same.
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Description

FIELD OF THE INVENTIONThe present invention relates to down hole fluid sampling tools and methods and, more particularly, to an improved fluid extraction tool and method for analyzing thermodynamic phases of complex fluids down hole.BACKGROUND OF THE INVENTIONSchlumberger Technology Corporation, the assignee of the present invention, has pioneered the use of Modular Formation Dynamics Testers (MDTs) and other down hole tools. The Modular Formation Dynamics Tester is one of several very useful instruments for obtaining formation fluid samples. The MDT tool is suspended by a wire line and then lowered into the borehole of the well. The instrument is secured to the walls of the borehole and samples of the formation fluid are extracted. Such a tool is illustrated in U.S. Pat. No. 4,860,581, issued to Zimmerman et al on Aug. 29, 1989.Fluid sampling tools comprise a pumpout module that can be used to draw fluids from the formation, circulate them through the instrument for analysis, and t...

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Embodiment Construction

Generally speaking, the present invention features a method of determining the bubble point and dew point of formation fluids down hole. Extracting fluids from earth formations by means of sampling logging tools is widely known and practiced. "Schlumberger Wireline Formation Testing and Sampling" (1996). The best known commercial tools used for this purpose are the Schlumberger Modular Formation Dynamics Tester (MDT) and the Western-Atlas Reservoir Characterization Instrument (RCI).

Now referring to FIG. 1, a typical MDT tool 10 having a PVT module 11 is shown.

For purposes of definition herein, tools that extract fluids from formations are generically called "sampling tools". Most commonly, sampling tools pump formation fluid for a substantial period of time in order to minimize contamination by mud filtrate. The MDT tool 10 has a pumpout module 12 for this purpose. During the pumping process, fluid properties are measured by various means, such as low-frequency electrical conductivi...