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Systems, apparatus and methods for measuring while drilling

  • US 4,553,226 A
  • Filed: 06/17/1982
  • Issued: 11/12/1985
  • Est. Priority Date: 01/10/1980
  • Status: Expired due to Term
First Claim
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1. A system for performing measurements in a drill hole during drilling operations using a drill string, said drill string defining a part of a fluid passage through which drilling fluid is forced to flow under pressure downwardly through said drill string from the earth'"'"'s surface towards the lower end of said drill string and then upwardly through the annulus surrounding said drill string from said lower end of said drill string to the earth'"'"'s surface, sensor means for sensing the magnitude of a downhole parameter and for generating a series of signal pulses representing said magnitude, a restriction within said passage, said restriction causing a pressure drop within said passage and as a consequence thereof creating a high pressure zone and a low pressure zone within said passage on different sides of said restriction with a consequent pressure difference therebetween, means comprising a bypass valve in a bypass between said zones for providing fluid communication between said high pressure zone and said low pressure zone;

  • first means for producing two lengthened secondary pulses in response to each of said signal pulses;

    second means operated responsive to said lengthened secondary pulses for causing initiation of the opening of said valve in response to one of said lengthened secondary pulses and for causing initiation of the closing of said valve in response to the other of said lengthened secondary pulses, thereby generating pressure changes in said drilling fluid; and

    ,transducer means at the earth'"'"'s surface to detect said pressure changes and to provide a measure of the magnitude of said parameter.

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