×

Method and apparatus for signal bandpass sampling in measurement-while-drilling applications

  • US 5,682,099 A
  • Filed: 06/07/1995
  • Issued: 10/28/1997
  • Est. Priority Date: 03/14/1994
  • Status: Expired due to Term
First Claim
Patent Images

1. A logging apparatus for use in a wellbore for determining an attribute of at least one of (a) said wellbore, and (b) a surrounding formation, when said logging apparatus is conveyed into said wellbore, comprising:

  • a housing;

    at least one transmitter carried by said housing, each transmitter being individually and selectively operable for producing an electromagnetic interrogating signal at a selected interrogation frequency for passage through said wellbore and said surrounding formation;

    at least one receiver, carried by said housing in a selected position relative to said at least one transmitter, each receiver being tuned to receive electromagnetic signals at said interrogation frequency to the exclusion of other frequencies;

    wherein a portion of said at least one of (a) said wellbore, and (b) said surrounding formation has an attribute value which can be derived from at least one of (a) amplitude attenuation of said electromagnetic interrogating signal as determined from measurements of said electromagnetic interrogating signal taken through said at least one receiver, and (b) phase shift of said electromagnetic interrogating signal as determined from measurements of said electromagnetic interrogating signal taken through said at least one receiver;

    a sampling circuit for sampling signals from said at least one receiver at a sampling frequency which is less than the interrogation frequency;

    a controller member for (a) selectively energizing said at least one transmitter causing said electromagnetic interrogating signal to pass through said wellbore and said surrounding formation in a particular direction relative to said at least one receiver, (b) for selectively obtaining measurements of said electromagnetic interrogating signal from said at least one receiver with said sampling circuit, and (c) determining a measure of said attribute value.

View all claims
  • 1 Assignment
Timeline View
Assignment View
    ×
    ×