Acoustic logging tool having opposed transducers

Claim 2

An acoustic logging tool for use in boreholes comprising in combination: a. generating means consisting of at least one pair of opposed segments of piezoelectric material, each of said segments being electrically driven so as to alternately expand and contract in a radial direction; the segments of each of said pairs being connected to electrical drive means so that when a first segment of said pair expands radially outward, the second segment of said pair contracts radially inward and when the first segment of said pair contracts radially, the second segment of said pair expands radially, b. electrical drive means for applying a voltage pulse to said segments, c. detector means spaced a distance from said generating means, comprising at least one pair of piezoelectric segments, each of said segments being located substantially in circumferential alignment with a corresponding segment of said generating means each of said detector segments being capable of generating a voltage in reSponse to pressure acting on the face of that segment; the voltage generated by each of said segments of said pair being substantially identical when each of said segments is subjected to forces which are substantially identical in magnitude, said detector segments being electrically connected so that their combined electrical signals are equal to zero when both of said segments are both subjected to inwardly or outwardly directed forces of equal magnitude and so that the electrical outputs add when said detector segments of said pair are subjected to forces of equal magnitude which tend to move said segments in opposite radial directions, d. electrical measuring means for measuring the time interval between the first application of voltage to said generating means and the first signal emitted by said detector means and display means for displaying said time interval.

Claim 3

An acoustic logging tool having a shaker source and receiver combination which accentuates shear waves and virtually eliminates the faster-traveling compressional waves; said acoustic logging tool comprising: a. a source having at least one set of paired transducer segments located on opposite sides of the borehole, the transducer segments of said pair being oppositely electrically connected so that a positive electrical signal causes one generator transducer segment to expand and the other generator transducer segment of the pair to contract, b. a detector spaced a distance along said borehole from said generator, said detector having at least one set of corresponding paired transducer segments substantially circumferentially aligned with said generator transducer segments, the detector segments of each pair being oppositely electrically connected so that positive voltage is emitted from one detector segment in response to inward pressure and positive voltage is emitted from the other detector segment of said pair in response to outward pressure, c. display means for displaying the combined detector signal.

Claim 4

An acoustic logging tool having a shaker source and receiver combination which accentuates shear waves and virtually eliminates the faster-traveling compressional waves; said acoustic logging tool comprising: a. a source having at least one set of paired transducer segments located on opposite sides of the borehole, the transducer segments of said pair being oppositely electrically connected so that a positive electrical signal causes one generator transducer segment to expand and the other generator transducer segment of the pair to contract, b. a detector spaced a distance along said borehole from said generator, said detector having at least one set of corresponding paired transducer segments substantially circumferentially aligned with said generator transducer segments, the detector segments of each pair being oppositely electrically connected so that positive voltage is emitted from one detector segment in response to inward pressure and positive voltage is emitted from the other detector segment of said pair in response to outward pressure, c. display means for displaying the combined detector signal.

Claim 5

The tool of claim 1 wherein the generator and the detector each consist of two pairs of transducers.

Claim 6

The tool of claim 2 wherein the generator and the detector each consist of two pairs of transducers.

Claim 7

The tool of claim 1 wherein the transducers are barium titanate transducers.

Claim 8

The tool of claim 2 wherein the transducers are barium titanate transducers.

Claim 11

The process of claim 7 wherein said first and second transducers are alternately caused to expand and contract by the application of an oscillating current source.

Claim 12

An acoustic logging tool for use in boreholes comprising in combination: a. a generating means consisting of at least one pair of opposed segments of piezoelectric material, each of said segments being electrically driven so as to alternaTively expand and contract in a radial direction; the segments of each of said pairs being connected to electrical drive means so that when a first segment of said pairs expands radially, the second segment of said pair contracts radially and when the first segment of said pair contracts radially, the second segment of said pair expands radially, b. electrical drive means for applying a voltage pulse to said segments, c. a first detector spaced a distance from said generating means, comprising at least one pair of piezoelectric segments, each of said segments being located substantially in circumferential alignment with a corresponding segment of said detector, each of said detector segments being capable of generating a voltage in response to pressure acting on the face of that segment; the voltage generated by each of said segments of said pair being substantially identical when each of said segments is subjected to forces which are substantially identical in magnitude, said detector segments being electrically connected so that their combined electrical signals are equal to zero when both of said segments are subjected to inwardly or outwardly directed forces of equal magnitude and so that the electrical outputs add when said detector segments of said pair are subjected to forces of equal magnitude which tend to move said segments in opposite radial directions, d. a second detector spaced a distance from said generating means, comprising at least one pair of piezoelectric segments, each of said segments being located substantially in circumferential alignment with a corresponding segment of said detector, each of said detector segments generating a voltage in response to pressure acting on the face of that segment; the voltage generated by each of said segments of said pair being substantially identical when each of said segments is subjected to forces which are substantially identical in magnitude, said detector segments being electrically connected so that their combined electrical signals are equal to zero when both of said segments are subjected to inwardly or outwardly directed forces of equal magnitude and so that the electrical outputs add when said detector segments of said pair are subjected to forces of equal magnitude which tend to move said segments in opposite radial directions, e. first electrical gating means opened by the application of said pulse to said generating means and closed by the electrical output of said first detector reaching a preset value, f. second electrical gating means opened by the application of said pulse to said generating means and closed by the electrical output of said second detector reaching a preset value, g. display means for displaying the time interval between the closing of said first gating means and the closing of said second gating means. 10. An acoustic logging tool for use in boreholes comprising in combination: a. a generating means consisting of a least one pair of opposed segments of piezoelectric material, each of said segments being electrically driven so as to alternatively expand and contract in a radial direction; the segments of each of said pairs being connected to electrical drive means so that when a first segment of said pair expands radially, the second segment of said pair contracts radially and when the first segment of said pair contracts radially, the second segment of said pair expands radially, b. electrical drive means for applying a voltage pulse to said segments, c. a first detector spaced a distance from said generating means, comprising at least one pair of piezoelectric segments, each of said segments being located substantially in circumferential alignment with a corresponding segment of said detector, each of said detector segments being capable of generating a voltage in response to pressure acting on the face of that segment; the voltage generated by each of said segments of said pair being substantially identical when each of said segmenTs is subjected to forces which are substantially identical in magnitude, said detector segments being electrically connected so that their combined electrical signals are equal to zero when both of said segments are subjected to inwardly or outwardly directed forces of equal magnitude and so that the electrical outputs add when said detector segments of said pair are subjected to forces of equal magnitude which tend to move said segments in opposite radial directions, d. a second detector spaced a distance from said generating means, comprising at least one pair of piezoelectric segments, each of said segments being located substantially in circumferential alignment with a corresponding segment of said detector, each of said detector segments generating a voltage in response to pressure acting on the face of that segment; the voltage generated by each of said segments of said pair being substantially identical when each of said segments is subjected to forces which are substantially identical in magnitude, said detector segments being electrically connected so that their combined electrical signals are equal to zero when both of said segments are subjected to inwardly or outwardly directed forces of equal magnitude and so that the electrical outputs add when said detector segments of said pair are subjected to forces of equal magnitude which tend to move said segments in opposite radial directions, e. electrical gating means opened by the electrical output of said first detector reaching a preset value, and closed by the electrical output of said second detector reaching a preset value, f. display means for displaying the time interval between the opening and the closing of said gating means.

Claim 13

An acoustic logging tool for use in boreholes comprising in combination: a. a generating means consisting of at least one pair of opposed segments of piezoelectric material, each of said segments being electrically driven so as to alternaTively expand and contract in a radial direction; the segments of each of said pairs being connected to electrical drive means so that when a first segment of said pairs expands radially, the second segment of said pair contracts radially and when the first segment of said pair contracts radially, the second segment of said pair expands radially, b. electrical drive means for applying a voltage pulse to said segments, c. a first detector spaced a distance from said generating means, comprising at least one pair of piezoelectric segments, each of said segments being located substantially in circumferential alignment with a corresponding segment of said detector, each of said detector segments being capable of generating a voltage in response to pressure acting on the face of that segment; the voltage generated by each of said segments of said pair being substantially identical when each of said segments is subjected to forces which are substantially identical in magnitude, said detector segments being electrically connected so that their combined electrical signals are equal to zero when both of said segments are subjected to inwardly or outwardly directed forces of equal magnitude and so that the electrical outputs add when said detector segments of said pair are subjected to forces of equal magnitude which tend to move said segments in opposite radial directions, d. a second detector spaced a distance from said generating means, comprising at least one pair of piezoelectric segments, each of said segments being located substantially in circumferential alignment with a corresponding segment of said detector, each of said detector segments generating a voltage in response to pressure acting on the face of that segment; the voltage generated by each of said segments of said pair being substantially identical when each of said segments is subjected to forces which are substantially identical in magnitude, said detector segments being electrically connected so that their combined electrical signals are equal to zero when both of said segments are subjected to inwardly or outwardly directed forces of equal magnitude and so that the electrical outputs add when said detector segments of said pair are subjected to forces of equal magnitude which tend to move said segments in opposite radial directions, e. first electrical gating means opened by the application of said pulse to said generating means and closed by the electrical output of said first detector reaching a preset value, f. second electrical gating means opened by the application of said pulse to said generating means and closed by the electrical output of said second detector reaching a preset value, g. display means for displaying the time interval between the closing of said first gating means and the closing of said second gating means. 10. An acoustic logging tool for use in boreholes comprising in combination: a. a generating means consisting of a least one pair of opposed segments of piezoelectric material, each of said segments being electrically driven so as to alternatively expand and contract in a radial direction; the segments of each of said pairs being connected to electrical drive means so that when a first segment of said pair expands radially, the second segment of said pair contracts radially and when the first segment of said pair contracts radially, the second segment of said pair expands radially, b. electrical drive means for applying a voltage pulse to said segments, c. a first detector spaced a distance from said generating means, comprising at least one pair of piezoelectric segments, each of said segments being located substantially in circumferential alignment with a corresponding segment of said detector, each of said detector segments being capable of generating a voltage in response to pressure acting on the face of that segment; the voltage generated by each of said segments of said pair being substantially identical when each of said segmenTs is subjected to forces which are substantially identical in magnitude, said detector segments being electrically connected so that their combined electrical signals are equal to zero when both of said segments are subjected to inwardly or outwardly directed forces of equal magnitude and so that the electrical outputs add when said detector segments of said pair are subjected to forces of equal magnitude which tend to move said segments in opposite radial directions, d. a second detector spaced a distance from said generating means, comprising at least one pair of piezoelectric segments, each of said segments being located substantially in circumferential alignment with a corresponding segment of said detector, each of said detector segments generating a voltage in response to pressure acting on the face of that segment; the voltage generated by each of said segments of said pair being substantially identical when each of said segments is subjected to forces which are substantially identical in magnitude, said detector segments being electrically connected so that their combined electrical signals are equal to zero when both of said segments are subjected to inwardly or outwardly directed forces of equal magnitude and so that the electrical outputs add when said detector segments of said pair are subjected to forces of equal magnitude which tend to move said segments in opposite radial directions, e. electrical gating means opened by the electrical output of said first detector reaching a preset value, and closed by the electrical output of said second detector reaching a preset value, f. display means for displaying the time interval between the opening and the closing of said gating means.