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Method and apparatus for obtaining selected samples of formation fluids

  • US 4,535,843 A
  • Filed: 06/08/1984
  • Issued: 08/20/1985
  • Est. Priority Date: 05/21/1982
  • Status: Expired due to Term
First Claim
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1. A method for obtaining formation fluid samples from a bore hole which method comprises:

  • (a) lowering a tool suspended by a wireline into said bore hole to a preselected level;

    (b) utilizing a pair of packers carried by said tool to isolate an interval of said bore hole by inflating said packers to expand them into sealing contact with said bore hole;

    (c) withdrawing fluid from said isolated interval and measuring its resistivity in a resistivity test chamber within said tool and sending the resistivity measurement to the surface via said wireline;

    (d) when the resistivity becomes constant, indicating that formation fluid uncontaminated by drilling mud components is being withdrawn into said tool, directing the withdrawn fluid into a second test chamber and measuring therein the redox potential, acidity and temperature of said fluid and sending results thereof to the surface by said wireline;

    (e) determining from the thus transmitted results whether it is desired to retain a sample and, if the determination is positive, pumping said fluid to one of a plurality of sample collection chambers within said tool, if the determination is negative returning said fluid to said bore hole;

    (f) deflating said packers to free said tool for vertical movement and moving said tool to another preselected location;

    (g) repeating steps (b) through (f) until the sample chambers in said tool are filled with desired samples; and

    (h) retracting said wireline to return the tool and the collected samples to the surface.

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